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Thin Films and Nanotechnology - Science topic

Thin Films and Nanotechnology is a group to exchange views on the HOT topic of Nanotechnology.
Questions related to Thin Films and Nanotechnology
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Research shows the material Tio2 + platinum electrode. Can we use some other cheap material for memristor other than platinum?
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I have just found this interesting paper where they have discussed the comparison between Gold and Platinum as the electrode material when fabricating TiO2 memristor.
Also, you can make memristor with NTC (Negative Temperature Coefficient) thermistors, which can be really chip.
Please let me know if you have already found some other chip materials to fabricate memristors.
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Are there interlayer materials like TaN for copper nano film deposition, so that copper doesn't diffuse into a silicon wafer, are there any such materials for tungsten deposition?
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It looks like Ti/TiN are common to be used as adhesion layer as the adhesion is usually poor between W and dielectrics.
Ref:
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The coating that I get is not good adhered on a glass substrate. The reduced graphene oxide had dried using freezer (-73 degree celsius). I'm using DMF solvent for reduced graphene oxide solution. Can anyone give me the suggestion for the good coating of reduced graphene oxide on a glass substrate? 
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Rita Joshi, did you measure the electrical resistance/conductivity of your substrate after rGO coating? Films of graphene are nearly 90% transparent.
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Eventually there are some missing points in this project...further detail may help
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@Uday Saha Thanks for the information sir
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If thin-film are made on conducting substrate(FTO) and on top contact pad is made, than I-V plot was measured by using two-probe which comes non-linear (typical of semiconducting material). Can anyone help me in calculation of conductivity value (in S/cm), carrier mobility, carrier density and On/Off ratio in this case?
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Nonlinear behaviour means, your materials doesn't obey the Ohm's law, but it has Diode Behaviour mateials.
Nonlinear means - how ?
generally graphically 4 quardent, urs, graaph 1 to 3 or 1 to 4 via 3
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What are the density and acoustic impedance values used for C60, graphene, SWNT, MWNT and graphene oxide in thermal evaporation, a physical vapour deposition process?
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Do you have found the impedance value? I am also seeking it.
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I am using TTIP as a precursor to producing TiO2.
Organic solvent: IPA
and Acid: HCl
I am preparing sol in different proportions, but i am ending with gel formation or milky white suspension after two days.
Please help me with producing stable TiO2 nanosol.
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Dear all, it is without indue doubt that TTIP is the most promising precursor it the conditions such solvent, concentration, are well selected. The following documents deal with the keytools for a successfull preparation of TiO2 nanostructures with the desired properties. Please check the following documents. I attached also the document recommended by Prof. Frank T. Edelmann. My Regards
10.1016/j.jeurceramsoc.2008.02.017
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In this paper (DOI: 10.1002/anie.200704788 ), the authors impregnated rutile TiO2 particles with a solution of titanium tetraisopropoxide in 2-propanol (the weight ratio of anatase phase to rutile phase in the parent solution 5 wt%) and
subsequently treated for 8 h at 423 K in the presence of a flow of wet
nitrogen to hydrolyze the titanium isopropoxide. After that they calcined the system at 400 C and obtained anatase- decorated rutile particles.
I just try to figure out how did they obtain epitaxial(Figure 3 in the paper) growth of anatase(!) on rutile although the obvious epitaxial stabilization from the rutile particles must encourage the transformation amorphous TiO2- rutile TiO2. I believe that the answer is in braces and that the precursor's structure encourage transformation of titanium tetraisopropoxide to the anatase phase. However, I am confused that before the calcination at 400 C the TiO2 phase was amorphous.
So, could anyone explain this to me?
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The nanoparticles on the surface have an unfinished crystal lattice. If the synthesis conditions (temperature, pressure) favor the formation of another allotropic modification, then it appears.
If you are interested in details write a letter to Pugachevsky. He knows this problem.
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May I get your opinion on 3 type detector above? I need feedback from researcher, not manufacturer.
Thanks.
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Hi Muhammad, six years since you posted this question, would you like to share your own experience on what you have? A private message will be OK if you prefer. Many thanks for considering my request.
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Reportedly, zinc sufide (ZnS) doped with Ag or Al or Cu is the most energy-efficient scintillator: one estimate says it's 30 %, that is, for an optimized composition (doping, crystal size, etc.) a single 10 keV electron fully stopped in a thin layer of this material results in the emission of ~ 1500 photons of nominal ~ 2 eV, a total of 3 keV in photon energy, over 4 pi. I have found numerous references with data, for all kinds of scintillators (for short-emission time materials at e.g., scintillator.lbl.gov, which does not include ZnS because its long emission time excludes it from this list), but very few (and old) references to a theory (e.g., Klasen, 1947).
What is the best place to find such a theory, preferably starting with something primitive that a non-solid-state physicist can follow?
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can anyone tell me please my AlGaN-BASED samples not showing any optical properties by PL test, is it possible to test CL or EL please anyone knows about this, and can CL or EL will be able to characterize my samples or it will be the same
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Hi,
I am working on fabrication of the tin perovskite solar cells. Tin perovskite solar cells are known for their low stability in ambient conditions due to intensive oxidation of tin. Therefore, it is highly advisable to encapsulate these devices after fabrication. I am curious to know how to encapsulate tin perovskite solar devices with low temperature thermoplastic sealant?
I am looking for suggestions to effectively encapsulate solar devices. Thank you!
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Before encapsulation you can coat your solar cells with silicon dioxide layer using spin on techniques. Such layer will make the bare side sealed against effect of oxygen and moisture.
We developed a novel encapsulation method named three flat plates modules.
For such method please follow the link:
and the book chapter:
Best wishes
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In solar cell applications I need to model PN junction, In lumerical's FDTD we can create new material in material database, there we can make any material with desired np density (electron hole density), but after that my simulation diverges due to material gain I suppose. 
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you can use solar cell analysis provided at analysis group library to generated charge carrier in respect to illuminated source, however I suppose that's not your problem, as far as I know, there is no direct way to perform doping to materials, FDTD knows material only with their index, you can look for your doped material permittivity then import that data to FDTD, at the Device module you can simply perform a doped material for electrical matters.
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I am trying to make the surface of silicon nanostructures super-hydrophobic. I am considering to use OTS and Toluene. I have not worked with these before. How should I mix them? Any precautions to be taken? Any other suggestions for getting super-hydrophobic surface? Thanks!
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Hi
I totally agree with Michael
​Kind regards,
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I am depositing pure metal oxide thin films by spray pyrolysis. I am getting good quality films. Whenever I am  trying with the doped metal oxides deposition with the same optimized conditions(distance between nozzle and substrates, molarity, solvents,quantity, temperature, air pressure and solution flow rate), films are not uniform. It is observed that after very thin deposition, powders are forming and it is in turn avoiding the deposition further. How shall I come out of this problem? What might be the effect of ultrasonic cleaning of thin films after deposition? Will it creates any defects in material and films?
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I think you can use solvent of higher boiling point and lower molar concentration of solution. Because solvent with lower boiling point evaporates from a certain height and form the powder. Solvent with higher boiling point can bring the droplet closer and due to levitation of the droplet it easily absorbs by the substrate. So, the film will be uniform and dense.
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i want to etch (remove) silver (Ag) from AAO template.Based on finding in internet, to etch silver, we need HNO3 and H2O. i need suggestion from others about the ratio@percentage on using these chemical. 
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We're currently setting up an oxide*-MBE system at the Technion. We're looking at qualitative analysis by RHEED (namely, we need a simple system), with the key tasks being monitoring crystallinity, reconstructions, and growth oscillations where applicable. My key requirements are reliability and beam stability.
I have quotes for RHEED systems from Staib and SVT.
I'd appreciate your input on the following:
Recommendations and suggestions for a manufacturer of a RHEED system (doesn't have to be from the above two).
Thoughts and input on external optics and related software for RHEED acquisition. Due to the simplicity of our requirements we'd like to keep the cost of this item reasonable.
* Note: we'll be working in low PO2 (<5E-6 Torr) so differential pumping is not needed.
Thanks in advance
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Martin Friedl I am the author of this software and just came across your reply as I was perusing the web for other RHEED software! Sorry for resurrecting an old thread, but if anybody would like to use FRHEED, I have recently made some major improvements to it (I have also created an installer for 1-step implementation). I will update the Github page this week as well for improved documentation. It can even run using a simple USB webcam if you would like to test it before committing to buying the CCD it was developed with (FLIR GigE Vision camera - Blackfly S Model 31S4M, ~$500).
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Dear all:
Have anyone deposited Al contacts on substrates of CdS and/or PbS, using an e-beam physical evaporation system ?
The following is happening with my CdS and PbS films ,
I'm trying to deposit a good quality Aluminum electric contacts with an e-beam evaporator, on the top of chemical bath deposited CdS and PbS thin films...
In both cases I'm trying to grow a deposit of 200 nm or 300 nm of Al. But when I run the deposits on the CdS films, the Al deposited above de CdS looks with a 'regular' quality, however sometimes I get a silvery uniform finish of the contacts.
But when I try to do the same on the PbS thin films, I always finish with a deposits with a somewhat white aspect, meaning that Al2O3 is growing on there, but this doesn't happen with the CdS films ...
Anyone has experimented something like it ?
Do you think the roughness of the films may be having an impact on whether pure-Al or a mix of Al and Al2O3 is growing on the e-beam deposited films ?
I am doing both deposits (Al on CdS and Al on PbS) with exactly the same conditions (i.e. current, grow rate, temperature and vacuum pressure).
Do you think it could be a matter of the surface of the susbtrate ? .. this would be unexpected, since I am growing 300 nm of Al... is not 10 nm, so the substrate should n't have an impact on the morphology of the above deposited thin film, and not to say an impact on the chemical composition of the surface of the films (Al films).
I hope someone can give me any help
Kind Regards !
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Dear Thomas:
The working pressure is 10-7 torr
The CdS and PbS were grown by Chemical Bath Deposition, these deposits were conducted in a different site, previously than the e-beam deposits.
I agree with your second comment,
Do you think that the big difference in the roughness of the films (between those of the CdS and PbS deposition). This hypothesis could be logical if I were try to grow 10 nm of Al, but I'm trying to grow 200 nm. What end deposited on the surface of the 200 nm-contacts should be affected by the roughness of the substrates. However, the roughness of my PbS thin films is on the order of microns, I saw the surface on SEM, and it is composed of big particules of PbS, measuring between 1-100 microns, the surface is highly non-uniform.
In opposition to the CdS films, where which the roughness isn't at the order of microns.
Do you think the morphology of the surface, in this case could be the problem ?
Even, I placed one of my PbS films and a black glass substrate in the same deposit, and the Al deposited on the glass ended up with a metalic aspect, but the Al deposited on the PbS film ended up with the white aspect, in the same deposition run. So same run and same conditions, but one ended metallic, and the other one ended white
Thanks for help ,
Regards !
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Effect of dopant on p-doped amorphous Si films?
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Dear Qaisar,
welcome again,
The doping atoms as they are impurity atom are different in size than the native silicon atoms in addition they are mostly ionized. When the electrons or holes passing near them when the drifting under the electric field applied they will be linked from their original path and therefore the doping atoms are considered as obstacles in the path of the electrons or holes and therefore they slow down the motion of these carriers. Consequently their mobility will be degraded due to the presence of the doping atoms.
I would like to get more information about the mobility by refering to trhe book in the link:
Best wishes
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Dear all :
I need help with the following question :
It is possible to grow n-type Bi2Te3 thin films, deposited on glass substrates using the e-beam technique ? If so, What would I require ? or What considerations do a have to take ?
I have acces to an e-beam deposition chamber and I have Intermetallic crucibles (BN-TiB2) and Graphite crucibles.
Then, I have a commercial bulk-Bi2Te3 n-type. So, my plan is to cut a piece of the ingot, and then breake pieces into little pellets, to place them directly into the crucible ,
Will this work ?
Thank you for the help ! :)
Regards !
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You can achieve the result if you use ion-plasma sputtering.
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I need to calculate the barrier height of the Schottky contact based on thermionic emission theory, so i want to know the Richardson constant value for indium oxide.
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The Richardson constant is expressed by
A* = 4 pi q m* k^2/h^3,
All what do you need is to search for m* of indium oxide and the the values of the physical constant and then you can calculate the Richardson constant.
The value for A= 120 A/cm^2 K^2 for m*=m0
For the derivation of the Richardson constant please refer to the book in the link:
Best wishes
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We are currently looking for an alternative source to buy some ZEP 520a resist as our supplier, Marubeni Europe PLC, increased the price for that material up to a level which is, from my point of view, no longer reasonable. So does anyone around here know other distributors than Marubeni for ZEP 520a?
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Hi all,
We've been developing a metal-organic resist which we believe has excellent etch properties. A recent paper appeared in Nano Lett., 2019, 19, 6043-6048 where we showed we could etch sub-10 nm structures into silicon and tungsten. I'd be very happy to send anyone a reprint or talk further if you are interested.
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I use polyacrylonitrile (PAN) to make the support layer. But the polyamide layer based on this PAN support tends to peel off from the support. The polyamide layer is fabricated via cross linking by interfacial polymerization. The two chemicals used for interfacial polymerization are MPD and TMC. Could anyone kindly give me some suggestion to avoid this peeling off problem?
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it depends on the type of support you use. we usually use slightly hydrophilic support as it doesn't hinder the movement of amine form aqueous phase to organic phase. If we use a strongly hydrophilic support, we would end up with less cross-linked polyamide film as the support will attract more amine
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I prepared a thin film sample ( by spin coating) of an average thickness around 350 nm. 
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First of all, sorry for my late answer, two years after the question !
If you think about film thickness less than 1 µm, thus deposited on a thick support, and about nanoporosity, i.e. microporosity (pore size < 2 nm) and mesoporosity (2 nm < pore size < 50 nm), BET analysis with commercial apparatus based on volumetric measurements is not sensitive enough or you need to analyse a very large amount of surface to analyse enough porous material. A small number of techniques exists to overcome this issue. They are generally based on techniques that couple adsorption-desorption (like BET measurements) with a technique dedicated to thin film analysis. It can be quartz crystal microbalance (QCM), spectroscopic ellipsometry, X-ray reflectometry (XRR), small angle X-ray diffraction, neutron diffusion, ...
For instance, I can advise to consult the article
Three characterization techniques coupled with adsorption for studying the nanoporosity of supported films and membranes
V. Rouessac, A. van der Lee, F. Bosc, J. Durand, A. Ayral, Microporous Mesoporous Mat. 111 (2008) 417-428.
but also more recent articles.
Regards,
Vincent
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Which equipment can be used to measure this?
How can I calculate the measurement?
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I am exploring IR reflecting materials grown on a glass substrate. Can graphene be used as IR reflector doped with other material.
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I strongly recommend you to read this publication:
"Optical Imaging and Characterization of Graphene and Other 2D Materials Using Quantitative Phase Microscopy"
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Chemical bath deposition can form SnS, SnS2 ans Sn2S3 compounds.
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I am trying to build a super cell for ZnO and TiO2 using input variables, natrd =2 , nobj = 1 , nobjaat = 1 2 abjaat = 2 2 1 (for 2*2*1 super cell). But, at the time of compilation it is giving error mentioning array is not correct... Can any one tell me whether I am using correct variables and their values ?
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The easiest, IMHO, is to export gif file from VESTA and use CIF2CELL code to generate an input file for Abinit.
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I try to make a thin film of coating PEG solution on glass substrate, but the resulted thin film contains many spots and unordered. Can anyone suggest to me the quantity of PEG that added to water to be suitable as thin film?   
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Substrate and liquid cleanliness is vital here. That's the usual reason for pinholing.
I assume you're working in Class 100 conditions.
Clean the glass with warm (50 - 60 C) Decon 90 (5%) solution in filtered 18 Mohm DI water. Then wash the surfactant solution off by 18 Mohm water for 20 minutes or so. The water should then drain off the substrate as a film and not showing spots or particulate manner
Work in a Class 100 environment and filter all solutions to 0.02 um. Ensure the liquid wets the substrate with appropriate concentration and perhaps use of a surfactant.
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In making a Quantum Dot LED, is there an ideal ITO resistivity (ohm/sq) that is used for optimal performance? I am aware that ITO on glass slide sellers list this specification often. Does sheet resistivity change the performance of an LED?
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Dear Reed Petersen,
Sheet resistance (Rs) or surface resistance or surface resistivity is electrical property used to characterise thin films of conducting and semiconducting materials. It is a measure of the lateral resistance through a thin square of material, i.e. the resistance between opposite sides of a square.
The key advantage of sheet resistance over other resistance measurements is that it is independent of the size of the square - enabling an easy comparison between different samples. Another advantage is that it can be measured directly using a four-point probe. The sheet resistance of the electrodes will effect amount of current that reaches the LED, impacting its performance.
The resistivity and conductivity can be calculated if the sheet resistance and material thickness are known. This allows for the materials to be electrically characterised, purely by measuring their sheet resistance.
A low sheet resistance is preferable from electrical point of view, but the lower the sheet resistance, the lower the transmission of the ITO. To decide its optimum value depends on the current density & the amount of transparencey needed.
A 100 nm thick ITO layer shows a transparency above 80% in the visible part of the spectrum and provides a low sheet resistivity of 20 Ω/sq (Sigma Aldrich Co, St Louis, MO.)
Most LED manufacturers characterize a product's thermal resistance for only one drive current, ambient temperature, and junction temperature. However, these parameters may change when LEDs are packaged into a system, which in turn may change the thermal resistance coefficient.
I hope I have answered your question.
With Best Wishes,
Samir G. Pandya
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Hello. In my project I need to immobolized silica-coated gold nanorods on cover slips, but I am not sure if this can be done by spin coating, just as I used to immoblized CATB stablized gold nanorods. Does anyone have experience? Thank you.
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place in or on an anion exchange resin and adjust the pH with a buffer solution to above the pKa for silicic acid. SiOH groups will deprotonate creating a negative charge Si surface and will be immobilized by the anion exchange resin.
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Suggest me a book or lecture to learn about AC complex Impedance spectroscopy analysis for thin films.
I want to learn from the beginning. Which author book or reference I can learn thoroughly? Suggest me a guide book please.
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Dear Cyril,
welcome,
If you have a two terminal electronic device having nonlinear I-V characteristics and you want to characterize it then there are three type of characterizations:
-The DC characterization by measuring its static I-V curve,
-The small signal ac characteristics by measuring its small signal impedance as a function of frequency. For its representation you just plot the imaginary versus the real part of the complex small signal impedance with the frequency as a parameter. An ideal p-n junction diode has an impedance diagram as a semicircle pointing out its small signal equivalent circuit as a parallel combination of small signal diode resistance parallel with its small signal junction resistance. It must be said that one has to keep the DC bias of the diode constant.
Lastly, it remains the dynamic or switching performance where one applies a unit step voltage voltage or current and measure the dynamic response as I(t) or V(t)
To see all these measurements including the impedance spectroscopy plot please see the link:
If the diodes are not ideal then one can get more than semicircle pointing out the presence of other interfaces than the major junction acting in series with it and contributing in limiting the current conduction in the diode.
Best wishes
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Is it possible for a gas molecule to act as a hopping site on the surface of semiconducting material? 
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This reference and those that accompany it could help you:
Electron-trapping and energy localization in insulating materials. Technological impact of space charge electron-beam characterization
AIP Advances 8, 095228 (2018); https://doi.org/10.1063/1.5047673
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How can we calculate the refractive index and and the absorption coefficient of materials that are thicker than the light wavelength (e.g. very thick film, transparent substrate, bulk single crystal subtrate)?
Is it possible to use the relation: α=1/d*ln(1/T) for calculation like in case of thin films?
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The answer should be yes. You can take this as your reference.
Optics & Laser Technology
Volume 34, Issue 3, April 2002, Pages 209-211
Calculation of the absorption coefficients of optical materials by measuring the transmissivities and refractive indices
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I have been asked to support an intern with the development of a ultrananocrystaline thin film MOS device. We have some already developed ultrananocrystaline thin films of Si-substrates, but i need to deposit a insulative thin film to form the MOS structure.
His project has a close deadline, so I need to find an insulative material that is easily compatible with ultrananocrystaline. My department currently has access to RF magnetron sputtering, evaporation and spin coating, I could access other resources. but the deadline is limiting my options.
 I myself have developed MOS devices before using insulative Bismuth based aurivillius structures, but these require annealing at temperatures above 550OC, and do not know how the diamond films would be effected by this condition.
I am currently investigating depositing SiO2 by RF-Magnetron sputtering, but I do not know if it will need post deposition annealing. Also my RF-sputter is only equipped with a pure Ar gas capabilities, and I understand O2 partial pressures are necessary for Oxides.
If anyone can suggest any easily formed insulative thin films for use on ultrananocrystaline diamond films. I would be extremely grateful.
Best wishes
David Coathup
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Electrical insulators as a new phase state of quantum matter with some bulk gap and some odd number of Dirac formations have recently been entangled with a two-dimensional model by us through an external magnetic field. The magnetic field used has its own impurities so much so that the eccentricity resulting from the turning point of magnetic critical insulation leads to aspects of compilation that have never been revealed by the “approximate approximation calculus” mostly used in a run under such circumstances.
Crystal and electronic structures have given us the topology that have made it likely for us to depend more on over-stuck service rather than on projections that go into manifolds and submanifolds of various dimensions. In additions, fulton heaters in this specific setting of complex systems where technique does not exist for efficient approximation, has led us to find even lower than submanifolds: something like up-submanifolds and down-submanifolds whereby the cloesed set of combining topological insulators itself has become the target in insulating the whole bulk without any regard for the gapless and/or edge services states. This means that the topological insulators that we are working on have been both gapless at surface and without such states so that they might be able to carry a pure spin current. However, this pure spin current is the point where we have made our own initiative provided through the closure of those areas where points cannot satisfy every path from one origin-set of the insulator to another point of it simulacrum. Therefore, we are actually depending on, so to speak, closure models for creating metainsulators, giving yet more models of simulations of magnetic insulators.
The surface of state of spin resolved ARPES works so that the focus of one direction is in Riemannian contrast to the zones that consequently appear throughout the folding holes as borderlines between submanifolds. For this, without any doubt, means that the dimensions of submanifolds where we are working on our different froms have been entangled with ergodicity as the totality of anisotropy that rises from insulation through coupling strength. The simplest form is, of course, happening within a two-dimensional partially anisotropic plane. In the most complex forms, they can even go into the quantum mechanic levels such as N-Hilbert dimension.
Roya Attarzadeh
Don Senior Prof. Reza Sanaye
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Hi, I need to cut single crystal (thin film )solar cells (Sunpower) for my research projects  by using laser cutter.
I have tried with a UV laser cutter but I found there were many shorts when I cut across the electrodes so that the shunt resistance is low and the I-V curves are weird.
My question is
1. What type of laser is best for my purpose?
2. What is the correct settins for the laser cutting?
3. What are the tips for increasing the shunt resistance ?
Please help us.
Thanks.
Best, Moohee
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Dear Moohee The best laser for your application depends on the reflection and absorption index based on the different laser wavelength. You have to check your material and find out the absorption and choose the appropriate laser wavelength. Besides, you have to pay attention to your laser parameters such as adequate repetition rate, laser pulse energy threshold, scribing speed and appropriate yield energy factor. The less amount of these parameters makes no cut and the higher ones make a rough cut and high HAZ effect. Good luck Azhdast
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We know different material has different density and acoustic impedance. A particular value needs to be specified to get the actual deposition thickness of a particular material through thickness monitor. I shall be highly obliged if anyone can provide me the value of acoustic impedance that should be set for In2O3 and Er2O3 in electron beam evaporation.
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For my monitor the Z-value is defined by acoustic impendence of the crystal divided by acoustic impedence of the evaporated material.
Do you have any method to test the thickness after evaporation? You could simply evaporate some material with a guessed acoustic impedence setting. If you make several samples with different thickness, a totallyincorrect impedence value should be noticable as a non-linear deviation from your tooling value.
This way you could tweak the impedence setting by fitting the target thickness to the measured one. But still, I would first try to simply evaporate some material without worring about the impedence value at all.
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I am making PVA films through solution casting. I am facing problem in delamination of films after drying. I made 4 wt% PVA/DMF solution and used glass petri dish for solution casting. Please also suggest best method for drying PVA/DMF solution to get PVA films(about 50-60 microns).
Looking for your suggestions.
Thank You!
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Dear Sir,
How to prepare PVA 4 mm sheet and PVA + GA sheet ??
Using vacuum assisted Compression moulding.
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It is known that, photoluminescence (PL), cathodoluminescence (CL) etc can reveal many details of the defects for a material. But, is it possible to interpret the defects from UV-Vis-NIR spectroscopy?
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After lot of useful discussion on this topic, I want to say that UV-Vis-NIR spectra can give information about the presence of defects. These defcts may be generated either by addition of some impurity or by the irradiation of samples by any ionizing radiation. The changes in the spectra will be observed in the form of shift in the position of original peak or in the change in the intensity of peaks. However exact peak generated due to defects can be obtained from difference spectra of sample before and after irradiation. FTIR spectra as well as difference spectra also can provide sufficient information about defects.
J. of Luminescence 130 447 (2010)
J. Non Crystalline Solids 357 3757 (2011)
Ind. J. Pure and Appl. Phys. 55 775 (2017)
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Ideas other than use of liquid nitrogen and epoxy resin?
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morphology and also crystallographic structure
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Is it possible to find zinc originating from the tin bath on the tin side of a float glass sheet? 
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This would be highly unusual for western quality glass. The float glass forming process uses high purity tin specifically to avoid issues like these. With that said if you are finding the contamination only on the tin side of the glass it is possible that the glass is coming from a low quality supplier who isn't using a high enough purity tin in their bath.
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I have seen procedures suggesting repeat spin-coating and curing. Others suggest simply pouring into a mold to desired thickness and curing. 
I would like to use the stamp for transfer of nanostructures between substrates as described in the link.
Thanks
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Kajal
You can get a larger area uniformly thick 2 mm PDMS sheet by creating a mold that dictates the shape of the PDMS, and then pressing or casting the PDMS into that mold. Let me know if you need help.
Andrew H. Cannon, Ph.D.
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I am preparing a thin film of cadmium Sulfide (CdS) in powder form using the thermal evaporation technique (closed sublimation). I have problem in that
1) the films are not uniform and
2) some times my crystal monitors gives me readings of the progress of thin film thickness but when I open the chamber the films are blank.
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Another question, wich evaporation boat should work better for CdS CdSe, CdTe, molybdenum, Tantalum or Tungsten?
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Dear all,
Can anyone suggest me the easiest way to assess the boron concentration in a thin silicon film (50nm) deposited on a glass/SiO2 substrate? Will EDS in SEM help? There are literature available on using FTIR for this purpose.. Kindly share your ideas.
Thanking you,
Jose
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EDX could work if the doping is higher than 0.5 at.%, i.e. you should have alloying, not doping. SIMS is a good idea. You can see the depth distribution of boron and confirm the layer thickness. I hope you have good standards for the SIMS measurements.
By FTIR is also possible to determine the doping concentration of B in Si from the area of the absorption peak.
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We've looked at an epitaxial film of GaN on a Si substrate using real time 2D Bragg XRD Microscopy (2D XRD rocking curve analysis). This specimen also had intermediate "buffer" layers of AlxGa1-xN and AlN. The XRD rocking curve Bragg profiles were examined at various topographic locations. The (0002)s reflection was utilized. The vicinity of the GaN (0002)s reflection was probed in reciprocal space using the ω-2ϴ scan mode to acquire the Bragg profiles.
We need some help! We're on the verge of a solution. Check out this data set and analyses for a GaN-AlxGa(1-x)N-AlN-Si sample wafer. I have the 3D XRD rocking curve data collected using a commonly available lab based XRD instrument below 2kW. I have the relative intensities for five distinct Bragg peaks around the GaN (0002)s reflection.
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SNR to COD relationship for the above data set at location "800" on topograph.
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spin coating
THICKNESS OF P3HT: PCBM
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Dear colleague Dr. Amr,
Peace be up on you, your question's readers and all RG members
There three methods to check and measure film thickness; you can use one of the following according to condition of the film.
Film thickness can be checked by
1- An interferometric method, more details is available at: TOLANSKY S. Multiple beam interferometry of surfaces and films. London: Oxford University Press, 1988: 147.
2- Using mass of the film, m according to the next details::
W1 is the weight of cleaned substrate
W2 is the weight of cleaned substrate plus film
W2-W1= the weight of the film
ΔW=mg
m = ΔW/g
m=ρXV ; ρ, is the density of film material and V is the volume of the film
the Volume = (Width X Length X Thickness) of the film
3- SEM or AFM (film-substrate ) cross section
I wish this is useful and help you.
A. El-Denglawey
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I want to calculate the wetting force of SAC305  on cu substrate.
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thanks your interests.
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I prepared TiO2 then deposite cobalt oxide over it. when i measure the EDX there was a Co in the sample. On the other hand the XRD for this material there is no peaks for cobalt oxide. my question is how can i determin the oxide form of cobalt is it Co2O3 or CoO
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X-ray absorption spectroscopy (EXAFS and XANES) will give distinct results specific for all the different Co-O species.
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Vantablack are nanotubes of carbon with Emissivity and absorptivity iqual 1 is a excelent conductor of heat  but a need more information principal in it has behaivor front anything
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thank for all
@Vicent
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I saw and read researchers using W-H plot to find crystallite size n strain on powder sample. Very limited research use for thin films. For my sample with the XRD peaks consist of Ag and Si3N4 and combination on both (attached). Can I use W-H plot for Ag peaks only? Is it reliable?
Some of information that I read in researchgate question saying that. To apply W-H method on thin films should considered these :
1) at least 4 diffracted peaks is needed for accurate result
2) neglect the effect of "preferred orientation"
3) W-H work preferably for randomly oriented crystallite and thus it is advised to have main randomly oriented crystallite in thin films.
Hopefully I can get advised or opinion regarding these. Thank you in advance.
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Dear colleague Umi Zalilah Zaidi
Have a nice time and good day.
Herein fined an attached paper teach you easy how to calculate crytallite size and strain of thin films.
I wish this is useful and help you.
Yous
A. El-Denglawey
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Has anyone done that work? Which kind of software can do that job? Crystalmaker or ? See appendix for reference file. Thank you.
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If still interested in similar problems, you may use the classical potential described here https://arxiv.org/pdf/1707.09059.pdf
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Why  CW laser is not enough to production nanoparticles from metals or semiconductors as ablation method ?
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External field-assisted laser ablation in liquid: An efficient strategy for nanocrystal synthesis and nanostructure assembly
Author links open overlay panelJ.XiaoP.LiuC.X.WangG.W.Yang
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Zno based Thin film Transistors used mainly Glass, Can we use Silicon instead of Glass
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Dear Aswin,
                  Could you plz specifiy the silicon substrate required? It is helpful for my research also.
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What is Elecrochemical etching? Can you please give me some article on it?
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A method of photo-assisted electrochemical machining of micromechanical structures from a silicon substrate having both p and n regions in a hydrofluoric electrolyte solution is disclosed. Both p and n regions of the silicon substrate may be selectively etched, with differing regions as etch stops, at controlled rates by the appropriate choice of cell bias p-n junction bias and illumination intensity.
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How to get good and homogeneous layer of compact-TiO2 other than spray pyrolysis or expensive Atomic Layer Deposition in perovskite solar cell fabrication? We want full coverage of this compact blocking layer over the FTO to prevent short circuit with the HTM/Au and maximum thickness of 100nm? How to achieve that?
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Dear Muhamad, 
You need to read this paper which employed low temperature TiO2 and simple deposition method by spin coating. The PCE is above 20%.
Good luck.
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Dear All,
I am fabricating an OFET based on quantum dots/organic SC hybrid, my first attempet failed when I tried to do a layer by layer solid ligand exchange to the quantum dot active layer (I used EDT, dacetonitrile, methanol, and the QD in toluene)
In a second batch I used mix of quantum dots/organic material in toluene without ligand exchange, and yet the device did not behave as transistor. 
what could be the reason behind this?
your contributions are greatly appreciated 
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Here the paper about Schottky devices which deposit PbS-QD on top of ITO. [http://dx.doi.org/10.1063/1.4804614] You can check the experimental section.
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I am working with PEDOT:PSS thin films that I routinely produce by spin coating on play microscope slides. For various measurements I would need to have films of different thicknesses.
Electropolymerisation is not an option and I can not go much lower in spinning speed to increase film thickness in that way.
So I was wondering if it would make sense to spin coat several layers of PEDOT:PSS on top of each other? 
I have not seen people doing it so I am afraid there is an obvious reason not to do this that I am not aware of. 
Thank you!
kind regards,
Karen
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Hej Joseph!
we have managed to successfully spin coat the second layer and the film was visually thicker (so less transparent); however I have admittedly not measured the thickness, neither the surface roughness. no visual inhomogeneities were present though.
best,
Karen
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Does anybody have experience (or references) on measurements of viscosity of nanofluids (solute size less than 100 nm) with different methods - are results significantly different using different techniques?
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as am not concerned with the synthesis of such polymer would i be able to get the prepared substrate on which i can directly deposit silver nanowires?
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Thank you all for helping me and sharing such good research articles. i have found solution to my problem as now am using simple silicon sealant and drying it on plastic sheets and then peel them off. the resulting sheets formed are highly transparent flexible and strechable heat resistant upto 300 C
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I have some particles that are about 300 micrometers tall in a PDMS mold. I'd like to collect these particles from the mold. I've tried using tape, and although it works, removing the particles from the tape one by one is not really efficient. Are there any suggestions? Thank you
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Hi Chong In Shin, 
Can you try some type of vacuum in order to remove the particles?
Are the particles on the surface of a piece of PDMS or inside of a channel? I feel that you expand a little bit more your question, I may be able to help you more.
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Now I'm preparing several TiO2 films for photoelectrochemical CO2 reduction. I want to fix the amount of TiO2 what I want at each film for comparing photoelectrochemical acitivty of TiO2 films.
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the key point is the thickness of masking tape. For each coating you should use same masking tape and a sharp blade (not glass or plastic rod). Also, if you decrease the area of film, thickness errors will decrease.
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Dear QE users and experts, 
 I want to calculate the charge density difference isosurfaces of graphene layers after adsorbing with some small molecules. For the single layer systems, I calculated successfully... but during the calculation of bilayers, am getting the following error.
Program POST-PROC v.4.3.2 starts on 1May2016 at 3:22:52
This program is part of the open-source Quantum ESPRESSO suite
for quantum simulation of materials; please cite
"P. Giannozzi et al., J. Phys.:Condens. Matter 21 395502 (2009);
in publications or presentations arising from this work. More details at
Parallel version (MPI), running on 16 processors
R & G space division: proc/pool = 16
Reading header from file all.charge
Info: using nr1, nr2, nr3 values from input
Reading data from file all.charge
Reading data from file g1.charge
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
from chdens : error # 1
incompatible gcutm or dual or ecut
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
stopping ...
Can anyone help me to solve this error?
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Dear Kamaraj Sir,
I am very new to Quantum Espresso. I am trying to get a charge density difference plot for a gas molecule adsorbed on the single layer graphene surface. Presently I am following your technique as written in your previous communication:
∆ρ=ρAB – ρA-ρB
Where, systems AB, A and B have the different number of atoms each. Then how can I make the charge files having same number of atomic coordinates?
Presently I am getting an error: incompatible gcutm or dual or ecut
Can you help me to solve this problem?
Thanks.
Bibhas Manna
IIT Kharagpur, India
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TTIP was used to form the Ti-sols at room temperature. Deposited thin films on glass slides were producing cracks and getting peel off after air drying. What may be the reason for immediate crystallization and how to get rid of this problem.
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Hi Sivagami,
The solution is to have a proper sintering of the TiO2 film. Just see our publication, link is given below. TiO2 sol is stable over a period exceeding an year (its not a tough job to do so). Just follow the simple steps given in the experimental section, Use cold water (10 degree) helps to form better sol with small particle sizes. Addition of TTIP should be very slow. Rest of the details for the film formation you can see in the publication. 
All the best
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while membrane fabrication, I have to consider the width (not thickness) very narrow which results in shrink to some extent ... does that affect the pore structure inside the membrane ??
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thank you so much
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I have seen most papers reported on the adhesion energy between SiO2 substrate and graphene. However, it is quite hard to find information or data on the adhesion energies for graphene on other metal substrates such as aluminum and gold which can be use as substrate for device applications. It is important to know the adhesion energy between graphene or even the other 2D materials and the targeted substrate for successful DRY transfer of the material. As the interaction between 2D materials and the targeted substrate are mainly based on the dispersive adhesion known as the Van der Waals force. Does anyone has data on the adhesion energy of graphene on metal substrates other than SiO2? Or is it that the adhesion energy between graphene and the targeted metal substrate is always higher than the polymer support used during the transfer such as PDMS, PET, and PVA. Any help is appreciated.
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@Ainan
Go through this paper. You may find your answer.
Good Luck.
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I have the absorption data of LSMO thin film on STO substrate, measured by ellipsometry in reflectivity mode. The backside of the substrate is not polished, so it'd assume as a infinite substrate. I'm not sure if only the LSMO absorption is in my interest (and not LSMO+STO), how can I remove the STO effect? (I tried abstracting pure substrate absorption from the data, but the result was negative at some wavelengths)
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Thanks a lot. It was very helpful.
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Is there is any relationship between photoconductivity and nonlinear optics?
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Dispersion and Nonlinear
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The stress and strain of inorganic materials such as Si films can be measured by Raman spectroscopy. Can we analyze the stress of organic materials such as polymer films by Raman spcetroscopy ?
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Silicon is single or poly crystalline and so the Raman features are quite sharp and homogeneous. Small shifts due to strain are therefore relatively easy to measure and monitor. I imagine, in organic films, the bands are broader and more inhomogreneous, so it may be more difficult to monitor the effects of strain.
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I keep getting too many peaks from the holder and backround maybe because my sample is too small(area 1cm squared). I tried putting the sample on a glass slide or on a piece of paper but it didnt work very well... 
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Dear Zeinab,
1 cm2 sample is not really small. I guess, your sample must be a thin film when you mentioned the area.
Use a thick and large size glass (at least 2 mm thick * 1-inch area). X-rays cannot penetrate up to that depth. In this situation, there should not be any peak due to the amorphous nature of glass. 
Also, use a 2 mm or 5 mm slit for passing X-rays and place your sample exactly at the center of the holder. 
Hope it helps.
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If i am depositing the TOP metal contacts of Au/Cr with the thickness 250 nm/3-5 nm. Cr is used as an adhesion layer and very thin (3-5 nm). Cr is first in contact with the film. Than how i can determine the workfunctions of the electrodes. Should i need to consider the workfunctions of the Au only or the Cr only. Or I haveto take the average of the both.
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As was pointed out before, it depends on which WF you're interested in. If you mean WF as measured from the top surface (e.g. the famous photoelectric effect experiment) then this would indeed be the WF of gold.
Since you refer to your film as a top contact, I assume that you refer to a device underneath it (e.g. this is a gate electrode, or a contact). In that case you'd be interested in the WF as "seen" by the substrate. This is often referred to as an Effective WF (EWF), especially in the context of Schottky contacts and MOS gates.
If this is indeed the case, the EWF is determined by the bottom few monolayers of the metal (i.e. a much thinner layer than your 3nm of Cr), meaning that you expect to get the EWF of Cr.
HOWEVER, this is not necessarily the case, and you need to consider several other possibilities:
  1. The Cr has oxidized during deposition or shortly after (e.g. when replacing/rotating between the targets in the deposition chamber). Since Cr really likes oxygen this can even happy in high vacuum conditions (depending on several other factors). If all the Cr is oxidized than you may observe the EWF of gold.
  2. The Cr and Au intermixed/interdiffused(/reacted?) under heating, e.g. at subsequent anneal. In that case the EWF becomes a complicated problem of the WF of alloys. I can refer you to some literature.
  3. The Cr is not deposited as a continuous layer (e.g. Volmer-Webber island growth).
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It's about fabrication of pressure sensor.
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Dear Jose,
Layer L is a typo error.
My brief process floe is like this,
1. Silicon wafer 100 orientation
2. SiO2 development on the device layer
3. TMAH etching from back side
4. Then development of Polysilicon on top os SiO2 using CVD
so my question is once I perform TMAH, can I take my device to CVD chamber, is that allowed. Please tell me if their any other alternate way to deposit Polysilicon after TMAH process. (provided DRIE/RIE is not an option as those machines are not available)
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When measuring the devices, I have found that the gate is connected however the device is not turning on i.e the Id-Vg curve is flat.
Any suggestions as to why this might be?
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Hi Jaspreet,
More info on your TFT structure would be helpful. The following is just general comments.
- Did you check the thickness of SiO2? Turn-on voltage might be too high if it is very thick.
- Was ODTS treatment done after the evaporation of Au? If it stays on Au surface, it could make the charge injection more difficult.
- ODTS treatment sometimes makes the surface too hydorphobic to spin-coat the solution on it. Did you check the polymer actually remains on the surface?
I would suggest to first try BGTC structure without ODTS treatment. BGTC has less trouble with the charge injection and P3HT would work even without ODTS (the apparent mobility would be lower, though).
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I have a device structure of ITO / HTL / Active layer / ETL / Al. I would like to know whether this device has a phonon assisted recombination or not. Can someone suggest me some experiments/ papers related to this?
or
How can one find the existence of phonon assisted recombination experimentally?
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Thank you for your answer and I really appreciate the info provided. What exactly I was looking is 'to find the phonon assisted recombination experimentally'. is there a way? anybody has ever done experiments related to that?
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Which companies do people buy those samples from?
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Please check with this:
Regards,
Amin
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What is behind logic in the doping effect of Sn-doped ZnO thin film to work on red shift effect in its band gap? Can it be lower than 3.18 eV?
what does it mean in the following article?
link:
"The redshift of the optical band gap is due to the deep states in the band gap, and a change of ~0.2 eV can only be observed when a substrate is not used."
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Dear Dr. Zekry,
As I have found red shifting in SZO thin films, but its not due to doping level increment. On that result, should I go with the application of red shifting or be stick with grain boundary deficiencies? Which one should work better? It will be great if you help me with valuable suggestions. 
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Does the epitaxy of Ag grown on Si surface have any effect on the surface enhanced raman scattering (using R6G)?
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Dear Abhijit Roy
As you know, the Raman spectroscopy of metals usually accompany by low intensities. When you use Ag nanoparticles deposited on Si non-epitaxially, it's usual that your peaks have low intensities because you measure dispersions in Raman spectroscopy. But crystals can make higher intensities in some special cases and also it may cause some shifts because of the size of your particles. I must see your Raman spectra after depositing epitaxial layer and the SERS spectra of Rodamine (R6G) to explain more and more.
with regards
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anyone could help me??
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Thanks a lot Prof. Oscar. Sure, I will have a look at this book. 
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for gas sensing
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you may try the deposition of multilayers by dip-coating method