Science topic

Silicon - Science topic

A trace element that constitutes about 27.6% of the earth's crust in the form of SILICON DIOXIDE. It does not occur free in nature. Silicon has the atomic symbol Si, atomic number 14, and atomic weight 28.09.
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I have some basic doubts-
  1. Why is TE mode so important in rectangular silicon optical waveguides? Why not TM mode?
  2. Why most researchers always prefer single mode over multimode waveguide?
  3. Could any one suggest a good article/paper for FDTD simulation of silicon waveguides in Lumerical?
  4. Does the rectangular cross section (width>height) of rectangular optical waveguide makes it polarization maintaining?
Thank you.
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Answer for question 3:
Ansys / Numerical 's
Lumerical MODE Solutions’ variational FDTD (varFDTD) solver efficiently simulates the propagation of optical radiation in a wide array of guided structures, from ridge waveguide-based systems to more complex geometries such as photonic crystals.
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Through thermal evaporation, I deposited a layer of Ag on silicon oxide / silicon substrate, but a malfunction of the machine meant that a much larger layer was deposited than necessary. I need to recover the substrate. Is there a way?
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We had an experience with dissolving silver films in a 1:1 mixture of H2O2 and NH4OH made from just ordinary pharmacy solutions. It worked.
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Where can I order a polished polycrystalline Silicon wafer? Any suggestions are welcome.
Thanks!
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Dear Tijmen Vermeij,
Some commercially available options are presented below:
Polished Silicon Wafer
(2447 products available)
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Polycrystalline silicon wafers
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I have to solve this problem, but im not an expert on CVD technique, i tryed to look for some usefull sources but i couldn't find anything can some one explain it or link something that could help?
Calculate the growth rate of the silicon epitaxial layer using reduction reaction of hydrogen and tetrachlorosilane mixture. The concentration of tetrachlorosilane in the gas flow is 0.1% (volume), the process is carried out under atmospheric pressure at the temperature set at 1273 K. Si: Ca = 5 × 1022 cm-3, hg = 7 cm/s (between 5 and 10), k = 8.62.10-5 eV/K - Bolzmann constant. Experimentally is established that surface reaction rate ks is 0.302 cm/s. Cg ~ pSiCl4/(kT)
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This question is explained in the Semiconductor Devices (Physics and Technology), S. M. SZE.
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The crystalline fraction can be determined by integration the areas under the crystalline and amorphous diffraction pattern.Are there any one help me to do it using Origin ?
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If we are going to study the exclusively Raman response from our film we can prepare such film with definite thickness that is sufficient for neglecting the signal from the substrate. It depends on the absorption coefficient of material of such film. According to the Bugger law intensity will be exponentially decrease by the increasing the deepness(or thickness of prepared film). If we carried on the experiments with bulk material and ion implantation inside it we can calculate the depth of penetration into bulk material of ions according to the nuclear and electron interaction formulas for implanted ions. The depth in this case will be 50-100 nm for Ar ion energy 5-10 keV. Such depth is small compare with wavelength of laser radiation (for Raman lase,r for example, argon laser 488 nm or 514 nm) but is greater than thickness of skin-layer for example Al,Au may be at 20 nm. The comparison of scales of these processes such as ion implantation and depth of penetration of laser radiatrion (or electromagnetic waves) will be useful for analysis the fraction of contribution of each part as surface layer (or thin film) as substrate (or bulk material).
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Dear Sir or Madam
Greeting, the following error appears when I attempt to extract the junction capacitance of a P-I-N diode (with two anodes and one cathodes contacts): "Cannot construct the curve." the codes I tried on the Atlas(not Athena) are:
extract start material="Silicon" mat.occno=2 bias=0.0 bias.step=0.25 bias.stop=-5 x.val=10 region.occno=1
extract done name="P-I-N capacitance" curve(bias,1djunc.cap material="Silicon" mat.occno=2 temp.val=300 x.val=10 region.occno=1 junc.occno=2) outfile="extract.dat"
Can anyone tell me which codes terms are incorrect? or How can I extract the junction capacitance (by voltage) in another way in Silvaco?
Regards
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How to extract area and peri component? Do you have equation? Help me...
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I am working on topology optimization for photonic devices. I need to apply a custom spatial filter on the designed geometry to make it fabricable with the CMOS process. I know there exist spatial filters to remove the pixel-by-pixel and small features from the geometry. However, I have not seen any custom analytical or numerical filters in the literature. Can anyone suggest a reference to help me through this?
Thanks,
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Many thanks for your reply.
The list of papers you've provided perfectly developed the concept, particularly the tutorial paper that goes through the optimization problem step by step.
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Dear Colleagues,
We are trying to simulate the XRR nanolayers to get information about theoretical curves, and then compare them to the ones we got from the experiment. But to get that we want to be sure, that our program is trustworthy enough to perform a simulation. We used Klockenkamper's book of Total Reflection X-ray Fluorescence Analysis. Firstly we took the data of nanolayer (a 70nm silicon layer on a gold substrate) from the book and simulated it at https://henke.lbl.gov/optical_constants/ then simulated it in our program with formulas given below (from the Klockenkamper book, given below), and compared the two simulations. But the results are not as they are supposed to be (the fig given below). Does anyone have an idea of where is the problem, and what we have to change/modify to get a better simulation?
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Thank you so much for your replay. It indeed helped when we had changed the ß value. We still have problem with the slope, because from Klockenkamper's book the equations give us only reflectivity curve starting from the critical angle. The line between angle 0 and critical angle is atrificial - automatically generated as straight line (as it is shown on the graph). Could you give us a hint how we can get the slope from 0 degrees to critical angle?
With best regards,
Regina
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We use E-beam to evaporate silicon. the soak and rise time is about 20 minutes to get a good melted silicon. the rate is about 4A/s. The process pressure is around 1.2E-4 torr. The process temperature is around 180 C.
For 200 nm of the film coated. the index is around 2.6 while the target is 3.2. Do you guys know how to optimize the coating to increase the index?
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Hi Jerry, what you outline above may well improve the index. However, the very earliest stages of deposition may have a bigger impact on grain size etc which may also impact on the overall performance of the film.
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Please explain the physics behind interface passivation by using intrinsic amorphous silicon. Can we replace amorphous silicon with microcrystalline silicon with similar quality?
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Dear Dr. Muzaffar Imam ,
I suggest you to have a first look at the following sources:
-Wikipedia - Amorphous silicon – Available at: https://en.wikipedia.org/wiki/Amorphous_silicon
-Optimisation of Intrinsic a-Si:H Passivation Layers in Crystalline-amorphous Silicon Heterojunction Solar Cells
J. Ge, Zhi Peng Gordon LING, , Johnson Wong, Thomas Mueller, Armin G. ABERLE
Energy Procedia 15:107–117 (2012)
-Replacing the amorphous silicon thin layer with microcrystalline silicon thin layer in TOPCon solar cells
Qiang Li, Ke Tao, Yun Sun, Rui Jia, Shao-Meng Wang, Zhi Jin, Xin-Yu Liu
Solar Energy, Volume 135, Pages 487-492 (2016)
Good luck and my best regards, Pierluigi Traverso.
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Has anyone got information about plastic tubing and the impact on stem cell growth? I am needing to change the tubing for the CO2 gas tank to the incubator and I want to avoid any potential harmful environments that may cause. I have some PVC tubing and silicone tubing. In previous labs I have worked in they have avoided using PVC as it could interact with some cleaning products and they were concerned that it could create a harmful culture environment. Does anyone else have any experience with this?
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It all depends on the material properties (which you can look up to determine if it will work). However, there are some tubing products sold that are meant for this sort of application (screenshots attache) that might Interest you.
In general, you want a material that is CO2 resistant/impermeable, broadly chemically resistant/inert, wear-resistant, corrosion resistant, humidity resistant, and temperature resistant for typical operating condition. I have seen some things here and there that say silicone is a great plastic BUT can be permeable to CO2 gas, so I try not to use it just in case. I’ve never heard of PVC concerns but if you have any reason to believe it will react then perhaps looking into other options might be worthwhile. Aside from the products in the screenshots, I have used Teflon and coated (for more chemical resistance), reinforced silicone rubber tubing before without any harm.
Hope this helps!
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I want to create Sodium silicate solution (Na2O = 7.5–8.5 %, SiO2 = 25.5–28.5 %) by dissolving silica beads (SiO2) and sodium hydroxide (NaOH) in water. I am an environmental scientist and my chemistry is a bit weak! someone can help me figure out the concentrations and quantities that will be used?
Note: 80g NaOH, 60g SiO2 in 100ml water gives Na2SiO3 (1:1 for sodium and silicon)
i need 1:2 for sodium and silicon
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Such a highly concentrated sodium silicate solution is not possible. You need a lot more water. Also, the idea to product of Na2SiO3 by the reaction between NaOH and SiO2 in a water solution is wrong. Sodium silicate is made by fusing together soda ash and silica sand. The resulting pieces of water glass are then processed by water vapor in to a water glass solution. Usual concentrations of the water glass are between 20 and 40%. You don't need to sintetize such a solution yourself, it can be bought very cheaply in any hardware store.
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Last time I did with 10ml water and take 20ul of it but the peaks are broader and no Sharp peaks observe?
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What kind of dye?
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On mesa silicon diodes: how can we remove unnecessary top passivation glass obtained after baking step ? With which tool and where can we find it?
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Nikolay Filippov thank you for your reply.
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We use Nitric-HF-Acetic mixture - HNA - to etch silicon. HNA is the most popular isotropic etchant. Some part of Si surface do not need to be etched. We try to use masks - various hard baked photoresists, adding adhesion promoters, try parylene too...but the HNA is so agressive that everything flakes off. And we also prefer to avoid silicon nitride mask. What might work better as the mask here?
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Alex,
Probably ;best to use reactive ion etching
Glad to see you are doing well. I live in Florida now.
Bill Carr
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Usually we perform measures of ATG to estimate the amount of inorganic charges in a composite (the charge been estimated by the amount of residus). Silicone rubbers, however, have silica as the main product of degradation. If I'm testing a silicone rubber filled with silica, can I identify what is degradation product and what comes from the filler? Or is there another way to determine the amount of silica in a silicone rubber?
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The easiest way for a 2 component silicone is to take the density of a piece and use the formula for slid mixtures: Then the total density is the total mass divided by the total volume. So ρmix=2M/(V1+V2). If you don't want to bother with the calculation, there are composite calculators on the web e.g.: https://phantomplastics.com/composite-density-calculator/
If you use 0.98 for silicone and 2.0 for silica you will get the answer +/- 1% for more precise info you need to know the precise silicone and silica. For that see the attached pdf:
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I am doing a device simulation of perovskite/silicon tandem solar cells in TCAD Silvaco. ITO of thickness 10 nm is used between top (perovskite) and bottom (silicon) cell. Unfortunately, simulation has convergence error. I tried to fixe meshing, used quantum tunneling as well as non-local band to band tunneling yet simulation did not converge after level of illumination 1E-5 Sun. Please help me to cope up this problem.
Thank You
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We would like to buy best quality silicon (p & n-type) wafers for silicon heterojunction solar cells. Many companies are providing wafers but don't know exactly quality of their wafers. your suggestions help to buy god quality wafers.
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Hi Venkanna,
You may make an inquiry at Alfa Chemistry, they offer kinds of good-quality materials.
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Dear all,
I use the kneading method in order to encapsulate silicon phthalocyanine dichloride in cyclodextrins (β-CD, γ-CD, HP-β-CD and Me-β-CD). My last calculations gave me encapsulation efficiency greater than 100%. Something went wrong... The protocol I follow is: Add i.e 5 mg of the dry complex of the cyclodextrin to 5 mL of DMF. The system is left under stirring for at least 24 hours. The solution is then filtered and fluorescence is measured.
Has anybody ever had a problem like this before and how did you overcome? How can I separate cyclodextrin complexes from the not encapsulated drug? I tried centrifugation without result.
Thank you!!
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Hi Eleni,
0. The complexation itself can enhance the fluorescence (see, e.g., doi:10.1016/j.jpba.2014.02.022, 10.1080/02652030701564555 )
1. It is a common mistake to assume that all the guest molecules form complexes upon kneading the components in a 1:1 molar ratio. More specifically, it is rare that equal molar ratio treatment results in complete complexation. That means the removal of uncomplexed guests is crucial. For the removal, one needs to use a solvent that is not a good guest for CD, does not dissolve the complex or the CD, and does not decompose the guest.
The silicon phthalocyanine dichloride content is an approximate value (~85%, according to, e.g., a known fine chemical supplier), you have to check the CofA for the measured value because the label contains the specification and not the measured value.
If some hydrolysis occurred before the complexation experiments, the content could be higher than expected. 2xOH~1Cl => ~5% more phthalocyanine content.
Because it is a reactive substance, it is difficult to find a suitable solvent. Maybe CH2Cl2, CHCl3 (be careful, CHCl3 always contains EtOH!), CCl4, DiPE, MTBE, or di-t-butyl ether?
2. The randomly substituted versions (HPbCD, RAMEB) suffer many systematic errors.
2.1 If the DS (Degree of Substitution) is a substituent/glucopyranoside unit, the calculation error of MW of the CD derivative is high. If the DS is in traditional terms (as the pharmacopeias define, number of substituent/CD), the MW calculation might be better. It is recommended to record 1H-NMR (D2O is a good choice because, in DMSO, the water overlaps with the methyl /RAMEB/ or methylene /HPbCD/ signals) and calculate yourself. Both ways give average values, but the calculation errors are different.
2.2 An additional problem is the water content of both HPbCD (2-5%) and RAMEB (0.5-1%). Measure the water content by drying (covered with paper, 90-100 oC, vacuum, in the presence of KOH/P2O5, overnight). It is recommended for the bCD (14% water), too. The freshly dried bCD or HPbCD adsorbs water quickly.
2.3 Because these data are rounded values, the calculation errors might significantly affect the weighing.
3. Did you record the fluorescence of untreated and similarly treated (with the complex preparation) guests? Is there a difference between the fluorescence spectra of dichloride, monochloride, and dihydroxy silicone phthalocyanine?
4. Because of the reactivity of the guest, the CD substitution cannot be excluded, though it is less probable. Either the multisubstitution of a CD or connecting two CDs can change the fluorescence signal strength. So can the single or double Cl=>OH exchange.
Good luck,
Laszlo
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I am unable to find articles on perovskite/silicon tandem thin-film solar cells. Is there any? or is there any technical issues while fabricating perovskite/silicon tandem thin film solar cells? Please guide.
Thank You
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Dear Muzaffar Imam,
The link below seems exactly what you're looking for ...:
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Dear friends and colleagues,
My team and I have been conducting research on the potential to perform a reaction involving SiO2 and Hydrogen Fluoride to create H2O and SIF4. Specifically we are interested in the H2O so we could then extract the oxygen via electrolysis and then react the hydrogen with SiF4 to get our Hydrogen Fluoride back along with silicon. Now that the Hydrogen Fluoride is present at the end of the reaction, we can redo the reaction all over again with a new batch of SIO2. The reactions are written out below.
4HF + SiO2 -> 2H2O + SiF4
2H2O -> 2H2 + O2
SiF4 + 2H2 -> 4HF + Si
However this reaction seems to have the issue where SiF4 quickly hydrolyzes before the Electrolysis can begin, to form H2SiF6. Thus the desired chain of reactions can not commence. Are you aware of any ways to mitigate this problem or are able to point me towards relevant literature on this matter? If I am misunderstanding the reaction dynamics please correct me. All feedback/help would be greatly appreciated.
Sincerely,
Georgiy Aleksanyan
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The Si-F bond is stronger and shorter than the Si-O bond
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Hi there!
Do you know about PhoenixSim simulator learning tools and helps?
if so please help.
Best regards
Yasin Asadi
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Dear Yasin Asadi,
See some helpful references below:
How does Phoenix's fluid solver work:
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Here’s a small guide on how to install Phoenix Sim from scratch and update it to 6.0. I also point out how to install those extra models that are available.
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PhoenixSim: A simulator for physical-layer analysis of chip-scale photonic interconnection networks:
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Can anyone suggest me a simple method to determine silicon to aluminium ratio in zeolites.
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By using EDS analysis.
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i am taking measurement for higher temperature from 25 degree Celsius to 450. Here i am following the Vander Pau method. i see in some cases there is some unwanted voltages produce. like sometimes negative resistance and some time positive higher value, for example 75 degree Celsius i get 80 Ohm and the next temperature(85) i am getting either negative or positive higher value like 5000 ohm. but the next temperature again make good relation with the first one . i am using Keitly 2450 source meter.
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You seem to have contact problems with the wires attached to your sample, and is aggravated/worsened with increasing temperature, moreover the electrode material used to contact the wires can get oxidized.
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Hi everyone!
I am looking for a non-toxic solvent that can melt Silicon during annealing or hot press experiment.
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I assume you mean "dissolve", not "melt", right. Unfortunately, there is a reason why it's always HF, KOH and H2O2 - and that is that there are no good alternatives. If you find one, you can file in a patent and get very rich.
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What is the best way to visualize with staining silicon in a plant? Without high tech equipment. I was thinking CVL but the inability to differentiate between silicon and lignin is an issue, so would a combo of CVL and PDMPO work?
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Dear Natalie Sch,
The following info below may be helpful:
Detection of Silica in Plants
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Visualising Silicon in Plants: Histochemistry, Silica Sculptures and Elemental Imaging
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For a silicon sample with photo-lithographical features between 10 – 20 µm in height. Will it be possible to estimate the height of these features using an optical microscope with about ±20% accuracy? Why? and if yes, how?
I know that Linewidth specification is usually set as ±10% of design value. However I did not understand how much this information is related to the question…
Would appreciate help with the questio.
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I need crystalline silicon with highers resistivity possible. Can I reach the higher resistivity than intrinsic silicon using n and p dopants at the same time? Or it is better way to use intrinsic silicon wafer and try to make defects inside the lattice?
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the principle of su-8 stick to the silicon after exposure and bake
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Dear Zhang Xinping,
Auxiliary information below may be of interest as well:
SU-8 Photolithography and Its Impact on Microfluidics
Rodrigo Martinez-Duarte and Marc J. Madou
Best baking procedure for photoresists are using convectional oven. Specially in SU-8 the ramp up backing is required e.g. to reach the temp. 120C , set the initial temperature to 60C and than ramp up with step of 5C upto 120C. For hard bake at 250C , the same procedure can be followed. You can check the attached publication of my group. EMIT full. ... Just to add to the other good comments, MicroChem advise using a hard bake temperature 10 oC above the maximum expected operating temperature. The hard bake can also be useful for annealing any surface cracks that may have appeared. There is a specific document issued by MicroChem regarding the hard bake process, I have attached it in case it is of interest to anyone. Hardbake Infor. mation.pdf.
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Does exist any interaction between the silicon contained into a silicon doped semicondutor and the acetone used to clean the sample? I use the sonicator.
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Is there any article related to silicone and acetone interaction?
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I am using Silicic acid treatment for estimating the silicon absorption in Rice. Is there any better alternative which is also cost-effective?
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Not an expert on quantifying silicon adsorption in rice; however, in 2006 I see are article that reports on a method for that quantifying. Take a look... as an alternative.
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Eventhough LPCVD SiN is etched by KOH in a very less amount, whenever a long duration(~5 hour) 30% KOH ethcing is done, SiN also gets affected. Is there any methods to prevent it?
What are the alternatives and options.
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These are both LPCVD processes. Low stress nitride uses predominately DCS (5.7:1) to NH3.
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I want to dope silver into p-type silicon but before start of my experiments i wanna know temperature coefficient resistance (TCR) of silver-doped-into-p-type silicon. The formula of finding it is given below picture. Can we find it before experimental work, How? Anyone can help please?
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Dear Shah Fahad,
In principle, you can get an estimation of the TCR for silver-doped p-type silicon by using the equation you give. A typical boron concentration for p-type silicon of Na = 1014 cm-3 and a typical silver concentration of NAg = 1015 cm-3 can be considered in this model. Consider also that the model imposed the limitation of NAg > Na becuase of the ln() domain limit. Typical values for the ED - EV energy of silver in p-type silicon vary between 0.25 and 0.34 eV.
The attached Figure shows an example of the magntiud order of the TCR for silver-doped p-type silicon calculated by using the proposed model. The previously mentioned parameters were considered. In general, a TCR between -0.06 and -0.006 are observed for temperatures between 300 (room temperature) and 1000 K.
To get a reasonable theoretical estimation for TCR before experimental work, you should know the exact NAg and Na concentrations.
I hope this information can help you.
Kind regards,
Simón Roa.
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I made microchannel on silicon wafer by fiber laser, but some substance was formed above the channel surface. I suppose this as silicon dioxide, and want to remove this from silicon channel.
But I can't use HF.
Then how can I successfully remove sio2 from si wafer? I don't want silicon wafer to be etched out as far as possible.
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Dear Sangguk Kwon,
Here it is:
Hydrofluoric acid (HF) is used to remove native silicon dioxide from wafers. Since it acts quickly, one needs to only expose the wafer for a short time (“dip”). HF is a dangerous chemical and protective gear must be worn when using it, in particular, neoprene or thick nitrile gloves and eye protection must be worn.
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Direct experiences with Biotechnological and Biomedical Approach? Therapies, long-term implications?
I'm not looking for definitions but protocols and methods that you personally have made and put into practice. Any information you have is welcome.
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masala nimada
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Please provide names for good suppliers of R&D grade silicone materials. Thanks.
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Dear Qun Ye,
Some additional info is shown below:
Who makes the silicon for chips?
Intel creates industry-leading and world-first silicon products. These Intel® chips are some of the most complex devices ever manufactured, requiring advanced manufacturing technology.
Computer chips, also known as semiconductors, are the brains of products like smartphones, cars, medical devices and most modern appliances. ​​The vast majority are made in Taiwan, South Korea and China.
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I'm currently trying to find the differential cross section for the products following proton irradiation of Si. something like the attached plot [Barak et al, Trans. Nucl Sci 2001] but at different proton energies. I believe the reaction is 14 Si(p,X), and I believe the data would be MT=5 in the ENDF data base. But I seem to be stuck in converting ENDF into something that would be easily readable.
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Dear Dr. Dave Hansen,
The following data may help:
ENDF-201 ENDF/B-VI Summary Documentation
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At instance, etching is achieved by the two familiar ways. Those are Isotropic and Anisotropic etching. In some cases, vertical etching also majorly attained, that too under direction dependent etching. I am wondering that how acids and alkaline solutions are preferred in different types of etching process and why ?
Especially, In order to etching Si crystalline thin film for semiconductor processing through anisotropic etching, I could see alkaline solution is preferred. Why not with Acids? and acids are preferable for isotropic etching (etch rate is same in all direction) process that it mentioned in the below literature.
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Thanks for your contribution Yana Suchikova . How do we do etch stop for certain circumstances after done with laser scribing ? Any idea?
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or we can use light with lower frequencies in the range of MHz?
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Dear Mahdi Vazvani,
What is the rise time of a photodetector?
The rise time is equivalent to the response speed of the device. It is defined as the time required for the photodetector output signal to change from 10% to 90% of the peak level. A good rule of thumb is to choose a photodiode with a rise time that is one fifth of the laser pulse width to be measured.
How can we measure the laser pulse duration less than pS?
Pulse durations down to roughly 10 ps can be measured with the fastest available photodiodes in combination with fast sampling oscilloscopes. For the measurement of shorter pulse durations, streak cameras can be used.
How is laser pulse measured?
The pulse duration, which is typically in the nanosecond regime, can be directly measured with a fast photodetector. The pulse energy may be measured directly (e.g. with a pyroelectric detector). In some cases with repetitive operation, it is calculated from the average power (from a power meter) and repetition rate.
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Hi,
I need an appropriate solvent to dissolve Silicone powder (Dark gray fine powder) for foliar application. I'll be thankful for your suggestions.
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Be aware of wording- SIlicone is Polydimethylsiloxane, a polymer. Silicon is a metalloid. The powder morphology description you provided sounds more like silicon than silicone. Alkali metals for silicon, organic solvents for silicone. Follow the answers above and do not be confused.
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Semiconductor device physics,
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Adding to the colleagues above,
One can look at the dopant distribution with depth measured for surface from an other point of view. It is how one produces such doping profiles, It is the doping technology. There is the epitaxial deposition where one normally produce layers with homogeneous doping. On can also grade the doping by controlling the doping atoms dose during the deposition. There is also the solid sate diffusion technology which results either in complementary error function dopant distribution or Gaussian distribution. There is also the ion implantation where the dopants are Gaussian around the pentation range of the implanted atoms.
These are the possible doping profiles according to their production method.
It is so that there are secondary factors which may slightly later the above theoretical distributions such as the presence of the crystallographic defects at high doping or the presence of the grain boundary.
You can find the analysis methods in the book of S.M.Sze VLSI technology.
Best wishes
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Hi, I'm currently trying to make pin fin array at Si wafer by RIE.
pin fin has 150um Diameter and 300um height, so I need to etch Si 300um deep.
I'll use CF4 gas, but I can't use photoresist for mask because there are not photoresist & facilities in my laboratory.
Which material can I use to make mask on Silicon without photoresist?
I can use E-beam evaporator & PECVD facility.
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No. RIE (Reactive Ion Etching) represents a combination of physical and chemical erosion: Here, chemically isotopically reactive radial is formed in plasma and accelerated towards the substrate.
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As we increase the doping concentration in silicon, even at room temperature the dopants are not fully ionized. Mathematically it all makes sense. But what is the physical reason behind this phenomenon?
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Dear Venkatesh, I presume that it primarily relies on the doping element. I'd like to know what is the doping element you use, so that it's quite easy to seek answer for your context.
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Dear colleagues- we routinely record local field potentials in freely moving mice from hippocampal CA1 and prefrontal cortex with ~ 125um depth electrodes, but would like to record multi neuronal single unit activity (and LFP's) in lightly restrained or freely moving animals. We would like to use silicon based shank electrodes with 16 to 32 recording sites, with one and sometimes two shanks- we have Intan recording systems. We have found some possible commercial solutions, but they are quite expensive and seem to be single use only. I was wondering if anyone had come across some more "reasonably priced" silicon or similar arrays? I am aware of tetrode methods and the more advanced CMOS based electrodes, but think the silicon array would be best suited to our current studies.
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These articles may provide you some useful information
1. Ahmadvand, Tala, Sara Mirsadeghi, Faezeh Shanehsazzadeh, Sahar Kiani, and Mehdi Fardmanesh. 2020. "A Novel Low-Cost Method for Fabrication of 2D Multi-Electrode Array (MEA) to Evaluate Functionality of Neuronal Cells" Proceedings 60, no. 1: 51. https://doi.org/10.3390/IECB2020-07087
2. Pelkonen, Anssi, Cristiana Pistono, Pamela Klecki, Mireia Gómez-Budia, Antonios Dougalis, Henna Konttinen, Iveta Stanová et al. "Functional Characterization of Human Pluripotent Stem Cell-Derived Models of the Brain with Microelectrode Arrays." Cells 11, no. 1 (2022): 106.
3.Pérez-Prieto, Norberto, and Manuel Delgado-Restituto. "Recording strategies for high channel count, densely spaced microelectrode arrays." Frontiers in Neuroscience (2021): 869.
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I am trying to simulate traps in TFET interfaces between oxide and silicon using sentaurus Sdevice. I included the traps in command file as follow:
Physics (MaterialInterface = "Silicon/HfO2") {
Traps( hNeutral Uniform EnergyMid = 0.22 EnergySig=0.02 Conc = 1e13 eJfactor = 0 eJfactor = 0 TrapVolume = 1e-11 HuangRhys = 3 PhononEnergy = 0.06 )
}
and include the parameter as follow:
MaterialInterface = "Silicon/HfO2" {
Traps{
Vth = 7.57e7 , 7.57e7
Xsec = 1e-15 , 1e-15
}
}
But the following error appear :
Unable to save dataset 'TrapOccupation_0(hN,Un)':
interface 'gateoxide2/channelregion' not found in grid file sdemodel_msh.tdr !
How could I fix this problem???
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After the process simulation, and for the final re-mesh for device simulation, include these lines:
############################
line clear
refinebox clear
refinebox clear.interface.mats
refinebox !keep.lines
refinebox interface.materials= "Silicon" # or any other material, you can add
# multiple lines like this one
# ###
# refineboxes here
####
pdbSetBoolean Grid No2DMerge 1
grid remesh info= 2
struct tdr= n@node@ # save this way to keep the interface
exit 0
############################
To check, when you load the structure, you will see a material called interface as in the attached image
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I want to do the analysis to check for the characteristics of solar cell for the Silicon nanoparticles. Can you please suggest me some reference to check the method of performing it using the SP 150 Potentiostat from Biologic and EC lab software.
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Hi Hadi,
Thank you for the manuals. I just wanted to check if there are any researches done using it. I just wanna see how the parameters are varied. The manual does not define the entire process.
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Hi, I am trying to start a deposition simulation for TiO2 film on Si surface. Si (001) surface is ready now I want to initiate deposition. Will use fix/deposit for Ti and O at 1 to 2 ratio.
I will be using Tersoff potentials for Si and O interactions and Buckingham/coul with MA coefficients for Ti-O interactions.
But what is the potential that best describes the Si-Ti interactions?
Thank you all.
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During deposition of TiO2 or Al2O3 on Si substrate, I am planning to have the sputtered atoms as charged atoms. But I am not sure if I should also make the subtstare Si atoms charged.
During deposition negative potential is applied at the target and thus they are sputtered by the impact of positively charged Ar atoms. Sputtered atoms can be neutral and also charged in the plasma with the ionized O atoms as well which combine with Ti to form TiO2. Si is grounded so I am planning to keep them as neutral.
what do you think?
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Hello,
I am coating Fibreglass yarn using silicone solution, currently I am not getting good bonding. Please suggest suitable coupling agent/silane which I can add in the silicone solution.
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I'd think that bonding fibre glass may be similar to bonding to glass and so Methyl Tris(methylethylketoxime)silane (MOS) may be suitable.
I see that some silicone sealants use a combination of silanes as shown here:
I hope this helps,
Best
Phil
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I tried to find options to remove the buried oxide layer (1um) with 22-um thick patterned silicon (SOI) wafer after bonding with glass wafer.
Initially, I plan to immerse my bonded wafer to HF, but that could affect the glass wafer....
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Dear researcher!
You can use Apiezon wax to cover all the areas which you do not to etch. Meaning you can cover the whole wafers except the holes.
This wax is very nice to work with as an etching mask.
Best wishes
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I need to form a SiO2 layer over a silicon wafer, I have a CVD setup and oxygen gas.
I don't know at what temperature and how long for deposition to take place?
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According to your purpose, an oxidation process using O2 is a good approach to get uniform SiO2. I suggest using 1000 oC and with a pump for better uniform. It is noted that O2 diffusion will be slow down when the thickness of SiO2 increases and therefore, the oxidation rate is decreased over time. I suggest using ellipsometry to confirm the thickness.
By the way, I'm curious why don't you buy SiO2/Si instead of making by yourself, if you want to analyze graphene. According to a previous report (ACS Nano 2013, 7, 11, 10344–10353), you need at least 90 nm to get a good characterization (other good thickness of SiO2 is 300 nm).
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Silicon is a multi talented element carrying several different benefits for horticultural plants. Previous reports revealed that using calcium or sodium silicate as a foliar application is increasing the photosynthetic rate. However, it isn't dissolved in water. How can I use it ?
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Thank you dear Ali F Almehemdi it really helps.
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I have Monolayer Graphene on a Silicon Substrate. I want to transfer it on glass substrate. I'm following the transfer process given in literature for transfer from catalytic metal substrate to other substrate. I want to etch out complete silicon wafers for this purpose. I have seen HNA (HF + nitric acid+ acetic acid) solution etching, will it help for my purpose? Can you tell me a detailed method?
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Hi Doctor Mohamed Boufnichel , As he didn't mention what type etching was that. How could you recommend him with alkaline solution? Please explain. It would be helpful in my case.
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Hello dear researchers
I have a question about the composition of silicon layer in liner paper in pressure sensitive labels and there is no article on silicon layer composition. All texts are in the form of patents. If there is a book or article on how to prepare silicone coating composition , please introduce me. Thank you all so much.
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Dear Len Leonid Mizrah,
Thank you so much , I found useful things in your answers.
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We produce ferrosilicon used by submerge method. In this method we use silicon, carbon and iron oxide.
W have a problem. 18 hours after end of produce, ferrosilicon become powder. Why? How can I prevent this problem?
Thank you
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Dear Ehsan Allahyari,
Take a look at the nuances of the ferrosilicon production:
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I'm using silicone resin for paint formulation (zirconia as a filler material) and It doesn't cure at atmosphere and elevated temperature also. And I tried titanium 4 isopropoxide, it dried but film becomes flakes while exposed to 250 degree Celsius in muffle furnace. Resin was bought from dow chemicals, the technical data sheet attached below for your reference
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Dear Abishek Palanivelu, the following chapter summerizes the different curing processes depending on the type of the resin. My Regards
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Are optical properties of a-silicon and poly-silicon different? especially their refractive indexes
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The following RG link is very useful:
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Hello Everyone, I have to simulate the piezoresistive cantilever of poly-silicon. During the selection of material in COMSOL, they ask for an Elasticity matrix. so which value should be entered. I am first time using the piezoresistive cantilever. If anyone knows the answer, kindly please reply.
Thank you
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you welcome Neethish Kumar Unnam.
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As we know calcium silicate is insoluble in water and ethanol. Then how doest it solubilize and dissociate in the soil?
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I am depositing Silicon using RF magnetron sputtering onto glass/CaF2 substrates for my research.
My standard process parameters are:
Power: 400W
Pressure: 0.24Pa
Base pressure: 3.35e-4 Pa
Target to substrate distance is about 6cm
Reflected power: 9W
Vbias: 360V
I have ran this process in the past and it has worked fine to produce a film of about 1µm thickness for about 100 minutes deposition time. But since last week when I try to run this process, there is no material on the substrates at all and there is also some amount of dust accumulated on top of the target after the process.
I thought this issue could be from the dark shield being placed incorrectly but I checked different position and it did not change anything. My other thought is that the substrate holder is somehow not grounded properly anymore and the material atoms are no longer being accelerated towards the substrate. I have no checked this as I am not sure how to check the bias between the target/magnetron source and the substrate holder safely.
Any advice/suggestions on what the issue could be or how to fix this would be appreciated. Thanks.
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Hi Philip. Did you, in the past record the bias voltage of your RF supply? This can be a useful guide as to if something had changed.
It actually sounds like the surface of your silicon target might have developed a tough oxide coating on it. (the DC bias voltage would been seen to have increased).
I recommend abrading the target surface to break through the layer.
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The punch holes on the microfluidic device are troublesome due to the punch tool, and when we connect the pipes to the device, when we give the flow, cracks occur in the input holes and the device don't work. Although the holes look perfect at first, cracks form when we give flow into them. What is the reason? In order to fill these cracks, I used silicone around the holes while the pipes connected to them, but the silicone did not adhere to the pdms surface, also other adhesives failed. What adhesive would you recommend to fill the cracks? How can I prevent these cracks?
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Dear Buse,
can you walk me through your process?
What are you using as a punch tool? We usually use Biopsy Punches and replace them after some time so that they stay sharp.
I experience cracks in the PDMS at holes when the hole is too small for the tubing (ie I use at least a 1.5mm punch for a 1.6 mm tube). Also, when the PDMS has been at too high temperature for too long I occasionally had the impression it becomes brittle. Can you try to cure / anneal it shorter / at lower temp?
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I want to know the calculation for following paper. I am attaching the paper. Please help me
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What are the advantages of using SiO2 substrate over Si substrate for monolayer graphene in photonics?
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Dear
Behnam Farid
Thanks for your complete answer.
In fact, I thought about the hot electron injection to the substrate.
As we're expecting localized or propagating plasmons in graphene, isn't it possible to have electron leakage from the graphene to high doped substrates? Instead, SiO2 or other insulators offer electrostatic charge transfer, which may facilitates the graphene-graphene hybridization in periodic structures like 1D graphene ribbons. Is this a valid claim?
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Please do add links of any papers available, if possible.
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The electrical characterization can be made by measuring:
The conductivity using the 4 point probes.
The mobility using the time of flight of the charge carriers between their sourced to their destination.
The carrier concentration using the Hall effect.
The minority carrier lifetime using the photoconductive decay.
You can find information about these methods in the link:
Best wishes.
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I see a plethora of research publications that use non-exact values of effective masses for silicon for both electron and hole at T = 300 K and effective density of states for electron and hole for silicon at T = 300 K. When it comes to choosing the exact values of these parameters, Professor Dr. Robert F. Pierret's two books " Semiconductor Device Fundamentals" and "Advanced Semiconductor Fundamentals" are the two reference books device physicists and modeling researchers should use. It derives the exact T = 300 K effective masses for electron and hole for silicon from T = 4 K reference value and effective density of states for electron and hole at T = 300 K for silicon are accurately mentioned in this book from accurately defined effective masses for electron and hole for Si at T = 300K. Then the intrinsic carrier concentration value for Si at T = 300 K also becomes accurate as per device parameter values given in this book. Practicing referencing the correct device parameters in modeling based research is pretty important for avoiding usage of anomalous device parameters related to publications and the above two books are the best sources for the device parameters mentioned in this connection.
Sincerely,
Dr. Nabil Shovon Ashraf
Associate Professor
Department of ECE
North South University
Dhaka, Bangladesh.
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Thank for this informations
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I am doing grain boundary simulation of multi-crystalline silicon based thin-film solar cells using TCAD Silvaco. On increasing number of grain boundaries in mc-Si region, Voc and FF are changing significantly but Jsc is not changing much. Please help me out to understand the physics behind it. Also, why interface defect density has high impact on Voc compared to Jsc but GB trap density affects Jsc more as compared to Voc?
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Do you have columnar structure? What is the thickness of the multicrysatlline layer? What is the of your junction? pn or pin one? It is clear that your semiconductor material parameters such that the photo generated electron pair holes will be collected before an appreciable recombination occurs.
The grain boundaries has more effect pn the dark current by increasing the reverse satiation current appreciably as the reverse saturation current is more sensitive to crystallographic defects than the Ish.
In order to verify my theory you need to calculate the reverse saturation current.
As the Js increases the Voc will be reduced. The fill factor also decreases because of increase in the series resistance and changing the squareness of the I-V curves. All this can you verify.
For more information about the effect of the grains on the solar cell please refer to the paper:
Best wishes
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I am running a thermal desorption GC/MS of a silicone sample. The chromatogram is clean and nice, however, one of the siloxane groups is showing as 5 peaks (well separated) at times 7.1, 8.2, 8.7, 9.8, and 10.5. What is the explanation for this?
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Really common, especially if this is the first run of the day. They come out of your septum and concentrate in your injector port or on the head of the column. Always make sure you run a blank as your first injection!
This can also come from phase degradation in your column, especially if you are injecting high water or acidic compounds.
Given that you are thermally injecting silicone you are almost certain to see siloxanes in your chromatogram, especially if you do not purge the air out of your thermal desorption tube before you begin to heat it.
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The two files are photocurrent pictures of silicon solar cell with pyramid and without by Silvaco TCAD. Compared with the picture wihout pyramid, the red line is not parallel the greent line at the point that the wavelength is 500nm. I want to konw the reason? I try to increase silicon thickness, however, this is not a reason. Please giving me answers! Great Masters.Thanks!
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At first you would like to define the different currents.
The other issue is that the effect of surface texturing is very clear. It enhances the absorbed light in the range of the shorter wavelengths of the spectrum while it seems to to increase the reflectance at the longer wavelength.
I think the matter of the penalization is not the big issue.
From my point of view you must change the representation of your data to represent the spectral response of the cell with and without the pyramid.
where you draw Icathode /I source.
You need also to determine the spectral reflectance with and without the pyramid.
In this way you can explain your results!
Best wishes
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I need to anisotropically etch 5um-wide, 100um deep holes into PDMS films. Has the Bosch process ever been successfully applied to PDMS? I found no published articles on the topic.
Please note: Mold replication is not a possible in my application, I need to directly etch the silicone film.
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The perflourocyclobutane step. Poor adhesion might be a problem.
what if you used one of the fluorosilicones? I think they mix in some Si with 1 CH3 and 1 3,3,3-trifluoropropyl - can be 100% or mixed with the dimethyl Si. That would enhance Compatibility and adhesion of the fluoropolymer.
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Dear Experts!
Silicon is used in plant tissue culture to enhance the growth and development of plants in vitro. I would like know the convincing physiological role of Calcium silicate (CaSiO3) in inducing totipotency/ Organogenesis/ Somatic embryogenesis?
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Yes, you are right Dr. Manokari, Silicon enhances the growth and development of in vitro shoots and roots via physiological processes only. It is still doubtful that it may induce Totipotency of plant cell.
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Hello there, I want to ask, how to determine the rpm and times to blend and mixing powder in powder metallurgy? As for my case, I want to blend iron and silicon powder but I don't know the right blending parameter like rpm and times. Can someone solve it for me and give the link of journal needed?
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I am reading about the instrumentation of Advance Compound Explorer (ACE). Cosmic Ray Isotope Spectrometer(CRIS) is used to detect the isotopes of energy range 100-600 MeV. I understand the mechanism for detection. A scintillating hodoscope followed by the silicon detector is used for the detection process. Here hodoscope is used to trace the trajectory of particle, while Silicon(Lithium doped) detector used to measure the charge and mass of particle. The charge and mass measurement has a link with the energy loss by the particle in silicon detector as well as the incident energy of particle.
Does the energy of particle remains unchanged when it passes through the hodoscope? If yes then how?
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The kinetic energy is unchanged when a particle moves in a uniform magnetic field because the velocity of the particle isn't affected by a magnetic field.
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Hello all! I'm trying to identify an unknown elastic band. I need to know if it is silicone-based or rubber (carbon) based. Here are my experimental parameters:
Dynamic headspace: incubate 12 mins at 80 C flow 50 ml/min
The trap is TenaxTA held at 50 C
Thermal desorption: starting at 40 C going to 280 C for 3 min, CIS starting from -10 C to 280 C
GC: DB-5 column, flow 1 ml/min, over 40 to 250 held for 10 mins
I am not seeing any siloxane peaks from my sample (I do see some siloxane peaks from the Tenax tube and fittings). All I'm seeing are long-chain saturated and unsaturated carbon compounds. No silicon-based compound. I am currently concluding that my sample is carbon-based rubber and not silicone.
Am I on the right track?
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Dear Mahsa Lotfi Marchoubeh,
Th following data may be useful:
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I am trying to bond carbon based PDMS composites, mainly with graphite powder, to bond either with Kapton tape with silicone adhesive or Kapton film. The PDMS composite is roughly 0.1mm thick. I have tried surface treatment with APTES and with MPTES for both substrates, had no success. My goal of this experiment is to thermally actuate it without debonding the bonded two layers. Any suggestions of how I can bond them without debonding or delamination between these two layers?
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