Questions related to Thin Film Technology
I have developed ZnO thin film in nano rod structure on glass substrate and have calculated the absorption coefficient (α) value from absorbance value. I also have plotted ln(α) vs. photon energy (hv) curve. Now I want to calculate Urbach energy from the curve but I donot know the calculation procedure. Please help me by providing calculation procedure. Here I attach the xls file.
As part of a project team, we are attempting to set up experiments that require the creation of a thin film of either chitin or chitosan. Any known methods that would be cheap and within specs?
I am fabricating ZnO based bottom gate top contact thin film transistor on Si/SiO2 as substrate. Thin layer of zinc oxide(ZnO) has been grown on substrate by RF sputtering. Finally source/ drain contact of aluminium (Al) has been deposited by thermal evaporation using shadow mask. Thickness of the SiO2 is 300nm, however a significant gate current (in the range of uA) has been flowing between bottom gate (Si) and top contact (Al).
How can I reduce the gate leakage current?
I am fabricating metal oxide TFT on SiO2(300nm)/Si(p++) substrate. In output characteristics I am observing minor linear modulation of Ids with change in Vgs but unable to get Ids saturation for as-deposited samples and linear modulation improves after air annealing. I also tried active layer of different thickness and vacuum annealed the samples still no saturation was found.
There was no gate current leakage in device.
Structure: inverted staggered; W/L= 2000/100 um
Reactive dc magnetron sputtering for active layer deposition; S&D= Ag (thermal deposition)
Characterization: Keithley 4200 SCS
Attached below are O/P and Transfer Characteristics of samples after Air annealing
I have a A-cut single crystal sapphire which I want to etch. Based on literature, I tried using KoH (W/o heat and with heat). But both of these did not work. Does anybody have experience with this?
Hello, I am working with AFM and I need to deposit different polymers on ultra flat stripped gold chips on silicon wafer. I would like to purchase the ultra flat stripped gold from platypus
I know these chips are meant for one use only, but there is someone aware of a good cleaning procedure I could use to remove the polymer and the possible contaminations and reuse the chip more than once?
Thank you very much for your help.
I'm making a poly(lactic-co-glycolic acid) film from CH2Cl2 in a flat aluminum dish. The film itself is fine, but sticks to the dish to the point of having to stretch and even warp the film.
Using a flat glass or PTFE dish might help, but I haven't readily found dishes that are truly flat (e.g. petri dishes I've gotten don't have a uniformly flat enough surface). I can't use a plastic dish that is not inert to DMSO, either. So, does anyone have a recommended casting dish or similar that they can recommend?
Aside from trying to find out the perfect casting dish or tool, is there any other suggestion for helping to readily remove the film? I had been thinking of casting a film of PVA first, and then just washing that out with water. Would that or something similar be efficacious?
I'm interested in permanently magnetizing a small piece of Ni or Fe. The size of the piece is quite small with diameter of 1 mm and thickness around 100 um - 500 um.
What are the field strengths that would be required to permanently magnetize the piece, and what would be the simplest method of achieving those?
I have been looking for the conductivity of Cu2O and CuO thin film where thickness ranging between 100-200nm and the minimum sheet resistance is something around 7.2Kohm/cm which means electrical resistivity of the film for a 200nm film will be around 1.44x10-3(ohm-cm) which is way too low when compared with other techniques.
Also, I could not find people showing this much low resistive in the past (or maybe I could not find a relevant paper). I wonder If someone could tell me what could be the possible reason for the decrease in the resistivity and also if someone could share some relevant paper with similar low resistivity then that would be great!
I want to calculate spectral selectivity of my thin film for optical analysis. I already measured the reflectance (R%) but unable to do emmisivity test in due to the unavailability of emmisivity instrument at my place. Is it possible to obtain the spectral selectivity with my reflectance or absorbance data only?is there any other formula that can be used?. your knowledge is highly appreciated
thank you in advance for your help :)
I'm trying to synthesize mono- or bi-layer MoS2 using a CVD process. Up to now, I've never success this CVD process without promoter.
So, I'm about to use PTCDA to promote MoS2 synthesis. I could find many papers that used PTCDA as a promoter. But they didn't mention about the details how to coat PTCDA onto SiO2 substrate.
I just prepared a PTCDA solution (26mg PTCDA powder mixed in 5mL of DI water) and tried to use spin-coating method (1000rpm and 3000rpm). But the substrate doesn't seem to be coated. The PTCDA solution was just washed out and remained a red stain as you can see at the attached picture. The red stain was an aggregation of PTCDA powder.
Can you share your method or any advice to coat PTCDA?
We have CuS thin film with (Cu:S) molar ratio (1:1), and we got nanoplates and very distinct and clear particles on the surface. But when increase S concentration (1:2) and (1:3) for (0.1 M, 0.2 M and 0.4 M), the film surface became non-specified aggregated particles (actually there is no particles just aggregations) with porosity. Any explanation for this significant change in surface morphology?
Many thanks in advance for your help and your time
I need to get an idea of how thick the native oxide is on a silicon wafer (100) that is kept at room temperature. The wafer has not been treated or cleaned in anyway.
I've synthesis colloidal metal nanoparticles and i need a protocol for adhesion of these metal nanoparticles on a glass substrate as it remain stable in water for several hours.
I want to grow graphene by CVD on different Ni thickness like 50 nm, 100 nm, 200 nm. Is it possible to grow? I want to know about the specific conditions at which it is possible. Please let me know if you have any idea about that.
During Polysilicon LPCVD deposition, some protrusions or polysilicon horns appeared at the Silicon wafer surface. Does someone have some data on this, that is to say some article on this phenomena the mean to identify the contaminant (by shape correlation or physical/chemical analysis).
Thin film of PANI deposited by CBD on silicon substrate posses no peak from XRD measurement while the bulk sample obtained from the same procedure posses peaks at low 2theta angle (~ 10 - 30 degree). Any theoretical explanation to substantiate these results?
Thank you in anticipation for your helpful contributions.
I am depositing indium oxide thin film (30 nano meter) and nano wire (200 nano meter) on p-type Si substrate using E-beam evaporator.I want to known whether oxygen vacancies play any major in indium oxide, and how it can alternate the optical, structural and electrical properties of indium oxide.
I have a problem depositing a thin SiO2 film by PECVD onto a Au substrate. The adhesion between SiO2 and Au is poor and I could not deposit Au and then SiO2 using the same equipment under vacuum. I am wondering if there is a way for me to improve the adhesion. Would a Cr layer between Au and SiO2 work (I could deposit Au and Cr with the same equipment)? Thank you very much!
i have sncl2 and ethanol and i do not have sncl4. is it enough to create a spraying solution for spray pyrolysis method by dissolving sncl2 in ethanol to create a transparent conductive oxide on a glass substrate?
I intend to make a thin film capacitor using solution processing. Alumina is used as dielectric layer and is coated on ITO coated glass via spin coating. ITO works as a bottom electrode for capacitor. The top electrode is made by silver paste. Initially the there is no contact between the two electrode but after sometime the two electrode is shorted and resistance between the two electrode is in Mega ohms. How can I prevent the shorting of two electrodes?
When annealing thin film at constant temperature for different times, the crystalline size (D) decreased and also the resistance (R) decreased. Both parameters lead to increase the sensitivity which is good for my sensor, but it is not right phenomenon to decrease D after annealing! Can anyone help me to explain this? In normal cases D must increased through annealing and R must decreased. If D increased the sensitivity will decrease which is not provide benefit for the sensor!
I used TMM to design a series of Anti-reflection coatings (ARC) for a mc-Si cell using Matlab. However can this technique accommodate the effects of an absorbing substrate in its formalism?
We have prepared a sample of multilayer thin films of TiO2/SiO2 onto the glass substrate by spin coating.
While doing reflectance measurement (using specular reflectance attachment at 5/15 degree with Shimadzu UV-1800) the reflectance value goes to 115/120/128%.
Can anyone suggest how to shootout this problem or what is the possible cause of it?
Thanks in advance.
R S Dubey
- On the preparation of WS2 by a one step hydrothermal process we are obtaining a yellowish colour, which resemblance that of the tungsten trioxide. What must we do
Kindly explain how should I Fabricate cell.
What I do is
1. Taking Mo coated glass slide and protect corners using polyamide tape during spin coating of czts.
2. After spin coating polyamide tape is removed and sample is annealed at 550 I'm h2s. (may be problem starts here. Since the part protected by tape now loses conductivity during h2s annealing)
3. Than I deposit cds, Zno and Al:zno after protecting the back contact again with polyamide tape (temperature sustainability upto 250C).
4. Finally I take IV between Mo and Azo. I am not making grids and to improve voc scribe the cells into smaller area cells.
My jsc and voc is coming good but fill factor is below 30 what should I do?
What is the standard way to protect back contact?
I have conducted the X-ray reflectivity experiments in situ and get more than 645 data. I hope to conduct the parratt fitting for these data and get the information about the thickness, roughness, and SLD. But, I cannot found some software which can support the batch fitting. If possible, could you please to inform me some software and tell me how to use it?
Thanks very much for your help.
I am looking for a water soluble material to make a clear thin film (thickness can be as large as 0.5mm), and its refractive index should be near 1.43-1.44.
I tried PVA (RI=1.50), the outcome is not desirable. I am going to try using PEG (RI=1.47) later, but I believe its RI is still too big for my application.
If anyone had a idea for that, please advice! Thanks a lot!
I'm currently working on chromium-gold thin films for MEMS applications. I'm studying the diffusion of chromium through the gold top film and its oxidation during heating processes and then "natural" ageing of the film (as diffusion and oxidation continue to occur after the chips have been processed and packaged).
We're currently testing different ways to limitate and/or stabilize this diffusion and oxidation phenomenon in order to stop the evolution of the metallisation characteristics.
Any ideas about this ?
How to avoid the Glow discharge during sputtering . During deposition the Voltage ramps upto 3 times higher than usual sputtering voltage and there is very less plasma generated and no films were deposited.The problem started after around 4 samples being deposited .
Thanks for your attention.
I have some question about the expansion mechanism of the hydrogel film, like expansion behaviors of the dry hydrogel in the saturate vapor pressure condition.( Macromolecules, 41(9), 3209–3218. http://doi.org/10.1021/ma7027775)
There was already some discussion about the expansion of hydrogel in water solution:
In the solution condition, some chemical group in the polymers, like carboxylic acid or amine, would be hydrolysed with the water. Then the changed group could repel each other and the polymers would be forced to expand.
However, i cannot make sure whether this theory can be applied in the previous paper. In this paper, the expansion mechanism is not detailed. But it have pointed "pure PNIPAM homopolymer films miss the possibility of internal cross-links to build up a gel". I'm confusing about this point. For the thin film, dose it mean that the pure PNIPAM homopolymer film cannot form the hydrogel structure, or lose the expansion ability? If the discussion about the expansion mechanism, as noted above, is true, i think the cross-links structure would not be necessary for the expansion in the thin film condition.
Anyway, i'm just the beginner in this field. If possible, could you share me some discussion about this topic?
Thanks very much for your time.
I am making model HDPE and LDPE thin films ( 20nm) on silicon wafers and gold carriers for analysis and further adsorption tests. I am using thin L/HDPE sheets dissolved in Toulene at 72 degrees and then dip coating the carriers. The goal is to create model layers that mimic the inner surface of HDPE containers. I have analysed the composition and morphology of my samples to that of the HDPe containers.
Which properties ( roughness, composition, wettability, stability during dynamic stress?) would have to be comparable between the 'real' sample and my model thin films, for me to conclude that my model samples are representative of the 'real life' material.
What is a acceptable deviation (of characteristics) from the real model to make the same conclusion...
Would it be possible to dissolve the piece cut out of the container in Toulene, make thin films with that and then put through the analysis. ( My gut tells me this may not be that easy)...
Are there any methods to determine whether by measurement or calculation in order to determine the work function of Indium Tin Oxide (ITO) thin films?
Although I've read a lot about thin-film hydration method, I don't really get the critical points of it. Such as, whether we should add water drop wise or the hole water. I'm working on mPEG-PCL copolymer. Besides, I like to know I can use centrifuge to omit the drug which are not loaded in micelles or not.
If someone knows a complete reference about this method, please let me know the citation.
I have been exploring possible ways to release thin films off bulk silicon wafers. I have been using a sacrificial layer of Cr/Al but in order take that layer off it takes 1-2 days in salt water. I am looking for something that needs little or no exposure to water during release
What are the strategies of achieving low resistivity and high transmission at the same time in fluorine-doped tin oxide tin films prepared by spray pyrolysis or chemical bath deposition techniques?
Besides purity, is there any advantage of sputtering technology over thermal evaporation for making metallised films? Which one is better if less adhesion is required on same substrate ?
Is there any difference in the final appearance of the film made using these two technologies - texture or gloss wise
I have performed anodization on mechanically polished and on chemically polished Ta samples at 15,25,50 V. This resulted in nano porosity on the surface of pore size from 25 -75 nm as voltage increased. Now the Ra value of surface decreased for chemically polished Ta (it increased when mechanically polished sample was anodized). Even though surface roughness decreased, the static friction coefficient of Ta in contact with artificial bone (Epoxy resin reinforced wth glass fiber) increased from 0.37 (etched) to 0.42 (anodized at 15V) and 0.41 at 25 V. Can someone provide an explanation of this?
Actually I have prepared some thin film on glass substrate. to use these as electrode in liquid junction solar cells I am interested to immersed the substrate in electrolyte.
The general formula given in many literature's
H(final)=H(meas.)-N(demag factor)*Ms(Saturation magnetization)
Does any one knows the formula for calculation of N for ultrathin film (total film thickness=1.8nm) with size(4x4 square mm)??
If N=0.5 Ms=1.0Tesla
How do we subtract demag. factors from the real field???
I am trying to make CZTS thin film using solgel method. Salts that I am using are Copper acetate monohydrate , zinc acetate dihydrate and tin chloride dihydrate with thiourea as a sulphur source.
As I increase the number coating beyond 5 layers, cracks start to develop in the precursor film.
Normally epoxy based resins are used for glob topping gold or aluminium wire bonds. Does anyone know of other materials which could be used for this purpose?
Vanadium oxide thin films prepared at different temperature from 473 K - 773 K with the step width of 50 K by using automatic spray pyrolysis technique.
I know that usually ZnS is deposited by RF system, but now only DC and pulse sputtering system in our laboratory. So can we deposit ZnS using DC or pulse sputtering system?
I'm preparing polystyrene thin film in ranged from 40 nm to 400 nm. The solutions were prepared from 0.5 wt% to 4 wt% in tolurene solvent. Does anyone know the prebaking recipe on hot plate? Baking temperature and baking duration on hot plate.
What kind of technology is suitable for the surface weight measurement of an opaque thin film ? (the weight is in the range of nanogram)
I was wondering how carrier scattering varies with the defects in thin film semiconductors. For example if iii-V semiconductor grows on silicon substrate because of the lattice mismatch there will be lot of misfit dislocations and growth twins. Is there any straight forward answer where it can be said that the carrier scattering increases/decreases with line defects or stacking faults. Or if I pose the question like this: how the mobility is affected by these defects. Will it increase or decrease by these defects? Or is it complicated to say? There exist lot of literature which mostly are misleading or I did not find very good answer in literature which can straight way gun down the question. Some literature says carrier scattering will be more with twin length some says it would decrease with coherent twin boundary length as twin boundaries are low scattering centers. I am not sure how to interpret. In my case I got twin formation between film and the substrate which drastically increases the conductivity. I am not sure whether to interpret that twin boundaries played a dominant role to reduce the carrier scattering and thus enhanced the mobility and conductivity or it has no effect on carrier mobility or scattering. Your thoughts will be highly appreciable.
I would like to know if there are any other methods to determine charge mobility apart from traditional time of flight methods etc., A method wherein you can measure if there is a change in mobility in the thin film of nm range (~100-500). Further, is it possible to measure carrier mobility in a vertical device? (example in a sandwiched configuration). I have come across literature wherein they have used impedance/admittance to measure the mobility. Does a I-V curve with a Space charge limited Current regime with definite parameters help in extracting any information regarding mobility? How well will the method apply to organic semiconductors?
Can anyone suggest me a starting point.
For forming thin film of metal doped nano TiO2, glass or Silicon surface is preferred and of what size?
I want to know if there is a way to determine the specific types of dominant scattering mechanism of fluorine-doped tin oxide thin films samples.
We prepared thin films (30 nm) of Cu3NbSe4 and the measured direct band gap is around 1.5 eV higher than that obtained for bulk samples.
I have taken AFM of my sample, which are thin films ( must be in <50nm thickness). I did the AFM measurements and I wonder the value called Ra( average roughness which is called the mean height) could be considered as height of the thin films grown over my substrate? Is it ok to report the Ra value as thickness of my thin films?
I would be happy to clarify my question if there exist any doubts. Thank you.
The films can be deposited on a substrate that would enable a thickness measurement, e.g. glass, silicon, etc. I would also appreciate advice on depositing very thin metal films by thermal evaporation.
we already had NiO nanoparticles. Could you suggest us how to use NiO nanoparticles by spin-coating and form a thin film? For example, what kind of solvent we should use to make suspension solution? and the concentration of the solution in order not to have aggregation in resultant film?
I need these values, in order to study the work function of pseudo alloy contact materials, namely AgZnO(92/8), AgCdO (88/12) and AgSnO2 (88/12).
I am investigating the process of encapsulating a very thin (20 micron) polyvinyl alcohol film inside a Hydroxyethyl methacrylate based, cross-linked, hydrogel. The PVA film needs to be able to dissolve into a clear, low water content, liqui-gel, with some shape memory. My issue is that the PVA film dissolves nicely but continues to absorb saline until it ruptures the encapsulating hydrogel. I have been adjusting the molecular weight and the degree of hydrolysis and also the concentration of PVA along with crosslinking with Freeze/Thaw cycles, Glutaraldehyde or Sodium Tetraborate to try and control the end point swelling.
Additionally when I reduce the PVA concentration to around 1% and cast in 20 micron aluminum mold, the dehydrated film is often too thin to remove from the mold ( but 10% de-molds and handles well, though at that concentration it appears to cause over swelling ). I have also tried glycerin as a thickening/plasticizer and a mold release agent like PS80 but no luck at the 1% concentration level.
I am currently running my photocurrent analysis with MoO3 thin film in Na2SO4 electrolyte (pH=1.50). When I apply the potential from 0 V to 2.0V, the I-V curve is abnormal. The onset potential was located at potential of 1.6V.
What I expected is the onset potential should located between the range of 0V to 1V. When I applied 0V to 1V of potential, I-V curve gave my a horizontal straight line. Anyone can help me on what is really going on? Appreciated much for any help.
I have taken the PL spectrum for my transition Metal (TM) doped ZnO thin films. I have obtained a Peak at 490 nm. In some reprints it was mentioned as green emission and in some reprints it was measured as blue emission. Which one is right? I have used an excitation wavelength 325 nm.