How to calculate band gap energy from UV-Vis absorption using Origin

Рет қаралды 133,116

Күн бұрын

For inquiries pertaining to consultative services on data plotting, analysis, and interpretation, please feel free to reach out to me at sayphysics@gmail.com
#bandgapenergy #originpro #sayphysics
0:00 what is Tauc plot?
1:15 direct and indirect electronic band transitions
3:00 derivation of the absorption coefficient from Beer-Lambert law
4:50 How to calculate band gap energy from UV-Vis absorption using Origin
6:55 Bandgap energy from absorption data using Tauc plot method
8:10 Band-gap (Eg) of UV-Vis Absorption Spectra using Tauc Plot
10:30 Bandgap (Eg) calculation of UV-Vis spectroscopy from absorption spectra
Exercise File (Origin File):
drive.google.com/file/d/1UdMH...
This KZfaq video titled "How to calculate band gap energy from UV-Vis absorption using Origin" explains step-by-step the process of calculating the energy bandgap of a semiconductor material using UV-Vis absorption data with the help of Origin software. The video starts by providing a brief introduction to the energy bandgap and its importance in semiconductor physics. The presenter then shows how to import the absorption data into Origin and how to plot it in the Tauc plot format. The linear fit of the Tauc plot is then used to extrapolate the bandgap energy of the semiconductor material. The video also demonstrates how to use Origin to generate a report with the calculated bandgap value and other important parameters. Overall, this video provides a clear and concise guide for anyone interested in calculating bandgap energy from UV-Vis absorption data using Origin.
"band gap energy" "UV-Vis absorption" "Origin tutorial" "spectroscopy" "optical properties" "material science" "energy gap calculation" "absorption spectrum" "bandgap engineering" "semiconductor physics" "optoelectronics" "solid-state physics" "bandgap analysis" "absorbance measurement" "optical absorption" "band gap determination" "materials characterization" "bandgap measurement" "optical spectroscopy" "band structure calculation"
All UV-Vis Analysis Video Tutorials:
1. How to calculate band gap energy from UV-Vis absorption
• How to calculate band ...
2. Calculate band gap energy from UV-Vis absorbance
• Calculate band gap ene...
3. How to calculate band gap energy from UV-Vis reflection (DRS) data
• How to calculate band ...
4. How to calculate band gap energy from photoluminescence (PL) data
• How to calculate band ...
5. Band gap energy with baseline correction using Tauc plot from UV-Vis absorbance data
• Band gap energy with b...
6. How to estimate the size of nanoparticles from UV-Vis absorbance data
• How to estimate the si...
7. Nanoparticle size, morphology, concentration and distribution from UV-Vis absorbance data
• Nanoparticle size, mor...
8. Calculate concentration from UV-Vis absorbance using Beer-Lambert's law
• Calculate concentratio...
9. How to calculate Urbach energy from UV-Vis absorbance data
• How to calculate Urbac...
10. How to plot and normalize FTIR and UV-VIS data
• How to plot and normal...
11. Absorption coefficient α calculation from UV-Vis absorbance data
• Absorption coefficient...
References:
www.nature.com/articles/s4159...
How is band gap energy calculated?
How is band gap energy of a semiconductor calculated?
How do you find the band gap of a material?
How do you calculate direct band gap?
Tauc used an equation in 1968 to calculate the absorption edges (bandgaps) of amorphous Ge and Si from their absorption data.
(αhν)γ=A(hν-Eg)
In this equation, α is the absorption coefficient, h is Planck’s constant, υ is the frequency of the incident photon, A is a proportionality constant (which is determined by the index of refraction, electron, and hole effective masses; however, it is usually taken as 1 for amorphous materials), and Eg is the bandgap energy. The important term is the exponent γ, which denotes the nature of the electronic transition, that is, when
γ=2 it is a direct allowed transition, and when it is equal to 1/2, it is an indirect allowed transition.
For γ=2/3 it is a direct forbidden transition, and for γ=1/3 an indirect forbidden transition.
Typically, the allowed transitions dominate the basic absorption processes, giving either direct or indirect transitions.
Thus, the basic procedure for a Tauc analysis is to acquire optical absorbance data for a sample in question that spans a range of energies from below the bandgap transition to above it.
Plotting the (αhν)γ versus (hν) is a matter of testing γ=2 or γ=1/2 to compare which provides
the better fit and thus identifies the correct transition type.

Пікірлер: 263

@yandalton389 3 күн бұрын

professor Shahid Ali Yousafzai I've been working with material optical characterization for quite some time but I sometimes forget a detail here and there, and this video was exactly what I needed. I will recommend your channel to my colleagues and collaborators. May I ask what are you working on currently? Thank you very much

@SAYPhysics 3 күн бұрын

Many thanks for the appreciation Professor. Your words mean a lot to me. I hope that your colleagues and students will like the rich contents in the big playlist.

@user-hl9wj8pv1k 9 ай бұрын

I hope you remember me SIR, your video on Tauc plot is a full complete explanation. It's simply WOW!! The clarity and depth of your explanation makes it evident how passionate and dedicated you are to your subject matter. Thank you for going above and beyond as a teacher and for sharing your expertise with a wider audience through your channel. Your commitment to education is inspiring, and I feel fortunate to have been your student.

@SAYPhysics 9 ай бұрын

Thanks for the appreciation Iqra Anjum. Your beautiful words encourages me to do even more. Stay blessed

@hopesworld3060 Жыл бұрын

Hello sir, I really wanted to thank you for this video and all the explanations. You saved my master degree thesis! Thank you so much!!

@SAYPhysics Жыл бұрын

Thanks for the appreciation dear 😊. I'm glad that it helped you. It'll be a favor now to share it with others. Thanks

@ronieu1 2 жыл бұрын

Thank you for a great explanation to measure the bandgap energy using Origin.

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear 😊

@indirabritopires6279 2 жыл бұрын

Ótima explicação, Professor! Ajudou bastante!

@SAYPhysics 2 жыл бұрын

obrigado pela apreciação

@KidsTube22342 Жыл бұрын

My dear Sir you are doing excellent job, God bless you.

@SAYPhysics Жыл бұрын

Thanks for the appreciation dear 😊

@change_the_way_you_think 2 жыл бұрын

Thank You Sir! For such a nice and informative (video)lecture ....

@SAYPhysics 2 жыл бұрын

So nice of you

@Brazil-Pakistan 2 жыл бұрын

Good tutorial video. Clearly and simply explained.

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear....

@jayashreev.l8761 2 жыл бұрын

Really a wonderful explanation sir. Thank you so much sir. It's a very very useful video fr students.

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear 😊

@annieprincy7313 Жыл бұрын

Thank you, sir, for this video. It really helped me a lot. clearly explained.

@SAYPhysics Жыл бұрын

Thanks for the appreciation dear. Please share it with your friends too.

@mathagroups2865 Жыл бұрын

Good morning sir. Two months before I was very depression, stress due to COVID 2 years waste in my research work.... I felt help less.. at the time I found your channel sir....all the characterization techniques I learnt from your channel 🙏🙏🙏🙏 yesterday I submitted one paper sir.... getting ready another paper .... looking journals Everything because of you sir 🙏🙏🙏🙏you are saved me....I never forget you in my life.... thank you so much sir..I salute you 🎊💐🙏 sir how to colour in EDS

@SAYPhysics Жыл бұрын

Your beautiful words touched my heart. May you have a healthy life. I'm glad that my tutorials helped you. Every day I'm receiving prayers and best wishes from around the world and it boost my ego to do even more. Please share it with others to be benefitted. Thanks

@ALPHA-ll4jy 5 ай бұрын

Thank you sir for your good explanation about band gap energy

@SAYPhysics 5 ай бұрын

You are most welcome. Thanks

@jaweriazartaj9731 Жыл бұрын

It's very useful content. Thank you for your effort. A little but important correction is needed. Before estimating the bandgap value from intersection of straight line with x-axis, the y-axis scale should be adjusted to zero as the starting point.

@SAYPhysics Жыл бұрын

Thanks for the appreciation dear. Yes, you're right when there's no offset involved.

@sardarali8741 Жыл бұрын

Dr SB ! Well explained.. Thank you

@SAYPhysics Жыл бұрын

So nice of you. Thanks 👍

@Dolldollee Жыл бұрын

Thank you for this video. It will be useful for my research :)

@SAYPhysics Жыл бұрын

Thanks for the appreciation dear 😊

@callbikram 2 жыл бұрын

Thank you for letting us understand

@SAYPhysics 2 жыл бұрын

You're welcome dear

@umadevitunga8180 2 жыл бұрын

Thank you so much sir...very helpful video

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear...

@Cutepuppy18 3 ай бұрын

Thank you alot sir. This helped me

@SAYPhysics 3 ай бұрын

Glad it helped. Thanks

@jiahuanzhang104 2 жыл бұрын

Hi, thank you for your detailed explanation. I'm having a question to the last step in the video: you read the bandgap = 5.6eV at (ahv)2=-50, should we read it at (ahv)2= 0?

@SAYPhysics 2 жыл бұрын

Yes. You're right. It's to be as y=0. Thanks for the appreciation dear 😊

@beatrizdesimoni6303 2 жыл бұрын

Thanks a lot for your video! I have one question: when you calculate the bandgap after extrapolating with the red line to the X axis, don't you have to rescale your graph so that Y axis start from 0? From your screen reader, you had something like Y = -47... Thanks once again!

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear. Yes, you're right. It is better to be at y=0 to calculate the x value. However, it's not a general rule. In some cases, we set an offset at some non-zero y values, like in composite type bandgap. The following article will help you understand it more. Thanks again for your input. pubs.acs.org/action/showCitFormats?doi=10.1021/acs.jpclett.8b02892

@kholoudalharbi1151 2 жыл бұрын

Thank you from my deep my heart

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear from the core of my heart

@davidoliva4044 Жыл бұрын

Thanks a lot! This was really useful:D

@SAYPhysics Жыл бұрын

Thanks for the appreciation dear

@saeed7601 5 ай бұрын

Thank you for the great explanation. However, I am wondering if the extrapolation should only cross at y =0. Please check.

@SAYPhysics 5 ай бұрын

Thanks for the appreciation dear 😊. Yes, you're right. In case, no offset or baseline correction is involved, it must be at y=0. The offset I have explained in the following video. kzfaq.info/get/bejne/ac2bltChlpbZn5s.html

@allinawhite9300 2 жыл бұрын

Thanku Sir Its A Nice Explanation ....

@SAYPhysics 2 жыл бұрын

Thanks for liking

@user-nc6lk2qr1r Жыл бұрын

شكراً على هذا الشرح الرائع

@SAYPhysics Жыл бұрын

Thanks for the appreciation dear 😊

@user-fb3wu5hg6v Жыл бұрын

It's very useful , thank you !!!

@SAYPhysics Жыл бұрын

You are welcome!

@jorgegutierrezcifuentes9050 Жыл бұрын

Excellent video!

@SAYPhysics Жыл бұрын

Thank you very much!

@TuanNguyen-eu4uz 2 жыл бұрын

tks you a lot for your video. This video is really meaningful for me

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear 😊

@SAYPhysics 2 жыл бұрын

Please share it with your friends as well. Thanks

@moses2061 4 ай бұрын

Thank you for the great explanation, what if the (ahv)^1/2 gives a great interpolation? how do you obtain the band gap?

@SAYPhysics 4 ай бұрын

Thank you for your comment! If (ahv)^1/2 provides a good interpolation, it suggests a linear relationship between the square root of absorbance and photon energy. To determine the band gap energy, you can extrapolate this linear relationship to the x-axis (photon energy axis) and find the point where absorbance becomes zero. This point corresponds to the band gap energy. However, it's crucial to validate this approach with additional methods or literature values to ensure accuracy.

@moses2061 3 ай бұрын

Thank you@@SAYPhysics

@SAYPhysics 3 ай бұрын

@moses2061 welcome dear

@ademzakariya1417 Жыл бұрын

thank you for this explication

@SAYPhysics Жыл бұрын

You are welcome dear

@ayapbergenshiknazarov7447 Ай бұрын

thank you for the useful video, I learned a lot of issues.how much can I download this presentation of yours? for answer, thank you in advance.

@SAYPhysics Ай бұрын

Thanks for the appreciation dear. Please share it with others too. Do you need the presentation part of this video? Thanks 😊

@meezanmeezansoomro229 2 жыл бұрын

Hello sir proud on such like teacher. I have a decision .to start the remaining course content of quantum David j grifith and also start it's problem solution . Because the student have many problme in quantum no one is able to solve it's problme so I request to u kindly do it

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear. Sure, may be when I'll start it the next time, I'll do its problems.

@naleg 2 жыл бұрын

Thank you for your video. In case that the absorption spectrum has more than one peak. the peak at a longer wavelength has lower intensity. which peak we will consider to calculate the optical bandgap energy.

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation. Usually, the first peak is the band-edge. Thanks

@user-gn3cx5tn4j 2 жыл бұрын

@@SAYPhysics Sorry, you mean the shorter wavelength 0.0?. Thanks

@brhaneamha 2 жыл бұрын

Thanks , can I use this to calculate for TiO2 too , It has indirect band gap

@SAYPhysics 2 жыл бұрын

Yes. Thanks

@monalisamallick9426 9 ай бұрын

thank you for the great video. I am new to this analysis. Why do you ignore the indirect graph? could you explain it more?

@SAYPhysics 9 ай бұрын

Thank you for watching and your feedback! In the video, I discussed both the direct and indirect graphs, but focused on the direct graph as it had a matching profile, making it more applicable for the analysis presented. If you have any specific questions about the indirect graph, feel free to ask, and I'd be happy to explain it in more detail.

@johnrom8787 4 ай бұрын

9:45 You are mistaken. you should have determined the band gap at the intersection with the x-axis at the zero level absorptin ((alfaE)^2 = 0). (alfaE)^2 cannot take negative values

@SAYPhysics 4 ай бұрын

Yes, you're right. It is better to be at y=0 to calculate the x value. However, it's not a general rule. In some cases, we set an offset at some non-zero y values, like in composite type bandgap. The following article will help you understand it more. Thanks again for your input. pubs.acs.org/action/showCitFormats?doi=10.1021/acs.jpclett.8b02892

@pritiroy889 9 ай бұрын

how you got to know which one is fitting better i.e. 2 or 1/2

@SAYPhysics 9 ай бұрын

The edge or slope can give us the idea. Thanks

@user-vu8se9kj6v 2 жыл бұрын

Hello i have some questions, I follow your step but the data isn’t as pretty as yours what can i do?

@SAYPhysics 2 жыл бұрын

In the same playlist, I've some more videos on the bandgap, watch them please. Thanks

@user-fx9vq9bv8j 4 ай бұрын

informative content

@SAYPhysics 4 ай бұрын

Thanks dear.

@amaragandapur1640 2 жыл бұрын

Thank you so much 👍

@SAYPhysics 2 жыл бұрын

You're welcome dear

@fluffybirb4758 4 ай бұрын

what if I have a thin film which is 100 nm? Should I convert it to cm or I can make the calculations using nm?

@SAYPhysics 4 ай бұрын

Thank you for your question! When working with thin films and calculating band gap energy from UV-Vis absorption, it's important to maintain consistent units for accurate results. In your case, if the thickness of the thin film is given in nanometers (nm), you should ensure that all other parameters in your calculations are also in the same unit.

@fluffybirb4758 4 ай бұрын

@@SAYPhysics Thank you for your answer

@SAYPhysics 4 ай бұрын

@fluffybirb4758 you're welcome dear

@XiZhang-ko3hb 2 ай бұрын

May I ask a question? When we calculate the band gap, we need to divide thickness of the film, should the unit of thickness be cm or nm?

@SAYPhysics 2 ай бұрын

Great question! When calculating the band gap from UV-Vis absorption data, the thickness of the film is typically used in centimeters (cm). However, it's important to be consistent with the units used in your calculations and to follow any specific guidelines or conventions relevant to your field of study. Thanks

@XiZhang-ko3hb 2 ай бұрын

@@SAYPhysics Thanks for your reply!

@SAYPhysics 2 ай бұрын

@@XiZhang-ko3hb You're welcome dear

@silver-ep8wn 10 ай бұрын

thank you so much!!!

@SAYPhysics 10 ай бұрын

You're welcome dear

@maliheghafari2979 8 күн бұрын

Hi, thanks for this video. I have a question regarding the last part which you are determining bandgap energy. I am wondering why you chose that part of the graph for estimating Eg, why didn't you chose the part from energy 4 to 5 to draw the line?

@SAYPhysics 8 күн бұрын

Thanks for the appreciation dear 😊 We need to select the region of interest by looking at where the slope has a well defined shape.

@maliheghafari2979 8 күн бұрын

@@SAYPhysics I really appreciate your reply. in my case I have two region that I can draw a line. i don't know which region is correct.

@SAYPhysics 8 күн бұрын

@maliheghafari2979 when you are having multiple regions, you will have to draw for each region. Sometimes, you need a baseline correction. The following video tutorial will further guide you in this regard. Thanks kzfaq.info/get/bejne/ac2bltChlpbZn5s.html

@AkbarHussain-lv6xf 2 жыл бұрын

Thanks alot Sir for detailed explanation. Would you like to upload more vedios about UV-Vis? Regards

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear. Let me suggest what remains, so that, I can work on them, if feasible.

@andresdariobetancourthurib477 2 жыл бұрын

Good video! Would it be correct if I extrapolate the high band in the absorbance spectra and later convert nm to eV?

@andresdariobetancourthurib477 2 жыл бұрын

...also. "A" you said is a constant (proporcionality, and in texts it says that is related with disorder and tail state). Why did you assume it like absorbance? Thank you so much

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation. I fear you can't, as we extrapolate the line onto the x-axis in relation to the y-axis. You can't change one (x-axis) while keeping the other the same (y-axis). However, in the following video, I have taken the x-axis as wavelength instead of energy. kzfaq.info/get/bejne/rpyiqdymprHNd30.html

@SAYPhysics 2 жыл бұрын

Yes, you're right that it is related to the disorder and tail state. However, for the materials which aren't modified, we have it as a constant. When its role is crucial, we'll have to put its value as per nature of our sample. Thanks

@aneebafatima8184 Жыл бұрын

This sheet is not working for my data and can't calculate the alpha and energy for my data . Please check ✅ so thankful to you !

@SAYPhysics Жыл бұрын

I rechecked. It is fine. May be you have problem with your Origin. Thanks

@dr.v.selvam4876 Жыл бұрын

Your videos are highly usefull, if you having videos kindly share, about Cyclic Voltmeter graph drawing, impedance

@SAYPhysics Жыл бұрын

Thanks for the appreciation Sir. I don't have any specific video on these. However, you may check the playlist to find any relevant one.

@Techno-replay-q5s 2 жыл бұрын

very elaborative and comprehensible video, thanks for sharing. Could you please help me in determing the band gap energy of my hydrothermally synthesized MoS2 nanoparticles which is in powder form..May I make its slurry in water and get absorption at differnt wavelength and proceed as you shown in the video?....Thanks in advance.

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear. Yes, you can disperse your powder in water or other dispersing medium. Thanks

@aswathik.1540 2 жыл бұрын

you can take UV for powder sample too.

@SAYPhysics 2 жыл бұрын

Thanks for the input

@aaclassroom Жыл бұрын

Dear Sir, Hope you are doing well. Thank you for this one. I have measured the absorption spectra of my CdS QDs for solar applications. I have used a glass solid TiO2 substrate, on which CdS quantum dots have been deposited via a technique called the SILAR method. The glass substrates are cut to match the cuvet size. You mentioned that the l is the thickness of the liquid and at somewhere you substituted the value of l to the thickness of the cuvet which in your case will be the thickness of the fluid, but in my case (glass substrate) it would be the thickness of the glass slide, right? and not the cuvet thickness?.

@SAYPhysics Жыл бұрын

As far as I understood your question, your thickness is the CdS QDs thickness. The absorption caused by the substrate is supposed to be subtracted as a reference. If you're using a dual beam spectrometer, put your undeposited glass slide in the reference slot, while the deposited in the measurement slot. Thanks

@aaclassroom Жыл бұрын

@@SAYPhysics Right Sir. I get it. I have used one glass substrate as a reference ( the undeposited one). You mean I should take the value of the difference between the deposited and undeposited one?.

@SAYPhysics Жыл бұрын

Yes. That'll be your sample absorption thickness.

@aaclassroom Жыл бұрын

@@SAYPhysics Thanks a million sir. It was really helpful and its always a pleasure to learn from you . Stay bless. More power to you.

@piyushsiroha5966 2 жыл бұрын

How we can find bad gap of a powder sample using uv vis spectroscopy please give the formula

@SAYPhysics 2 жыл бұрын

In this playlist, there's a video on DRS data calculations. Thanks

@lacienciacentral 2 жыл бұрын

Thanks a lot!

@SAYPhysics 2 жыл бұрын

You're welcome dear

@sandhulisanishyahettiarach2999 10 ай бұрын

Thank you so much sir

@SAYPhysics 10 ай бұрын

Most welcome dear.

@tayabkhan4407 Жыл бұрын

sir as you explained at (8:48), if we are still not getting the best fit. Can we go further and take Cube (of Absorbance and energy) instead of Square and then we can plot...

@SAYPhysics Жыл бұрын

Yes. In the beginning of the presentation, I have explained this which powers are to be taken in different situation. Thanks

@tayabkhan4407 Жыл бұрын

@@SAYPhysics Thanks

@Al-fk6yp 2 жыл бұрын

Thank you sir for the tutorial, very helpful :) Is there any an article or book reference that I can cite for this?

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear. There are so many references, you may find some of them as below; www.sciencedirect.com/science/article/pii/0025540868900238 onlinelibrary.wiley.com/doi/abs/10.1002/pssb.201552007 www.nature.com/articles/s41598-019-47670-y

@prasannadevic4376 2 жыл бұрын

Sir put up the video Vickers microhardness testing.how I calculated work hardening coefficient or Meyer index value

@SAYPhysics 2 жыл бұрын

There's a formula for the Vicker's hardness in which you use the diagonal lengths of the microindentation. I'll try to include it in the tutorial series. Thanks

@hamidrezajavidrad4234 2 жыл бұрын

Hello my friend, Thank you for your useful video. Could you please provide the reference for the absorption-wavelength data? Thanks

@SAYPhysics 2 жыл бұрын

Please check the video description for the references. Thanks for the appreciation dear

@Ashli2024 Жыл бұрын

The gamma in some measurements is 1 or 1/3 or 2/3. How can we find the proper gamma during our data analysis?

@SAYPhysics Жыл бұрын

In Tauc plot analysis, gamma represents the nature of the transition and is usually assumed to be either 1/2, 1, or 2/3. Each value corresponds to a different type of transition, such as direct allowed transition, indirect allowed transition, or indirect forbidden transition, respectively. To determine the proper gamma for your data analysis, it is essential to consider the characteristics of your material and the available literature. Experimental techniques, material properties, and previous studies on similar materials can provide insights into the appropriate gamma value. Consulting relevant research papers, textbooks, or expert opinions in the field can help you determine the most suitable gamma value for your specific material and experimental setup. Additionally, discussing with colleagues or experts in the field may provide valuable guidance and insights for selecting the proper gamma during your data analysis. Thanks

@AS-tp3cz Жыл бұрын

Thanks for a very clear explanation. Will the same method be applicable to determine the band gap of colloidal particles in a solution or we need to have a DRS data only.

@SAYPhysics Жыл бұрын

It works well for simple colloidal NPs, while for the core shell or functionalized NPs, the DRS results may work well. Thanks for the appreciation 😊

@AS-tp3cz Жыл бұрын

@@SAYPhysics Understood, thank you! Meaning, this method may work in either case, right? We don't seem to have an accessory to measure DRS and my carbon/Ti composite does show desired red-shift on the UV-Vis spectra, so I am thinking to proceed with the band gap calculations using the method you described in this video. Hope I am headed in the right direction

@SAYPhysics Жыл бұрын

Yes and I hope that you will find some comparison in the literature.

@anitabugalia7874 2 жыл бұрын

Sir if the curve has two or three linear parts, then how to decide which linear part is suitable for calculating band gap.

@SAYPhysics 2 жыл бұрын

This is something not very straightforward but requires some literature overhauling. Sometimes, such regions do mean a bandgap and sometimes it's an offset. I'm referring to an article, which will help you understand it more. Thanks DOI: 10.1021/acs.jpclett.8b02892

@anitabugalia7874 2 жыл бұрын

@@SAYPhysics Thanks

@nayadabdallah9917 Жыл бұрын

Hello! thank you for the video. However, I am still confused; some papers suggest that the direct band gap is obtained y = 1/2 while the indirect one is y = 2, especially for DRS analysis.

@SAYPhysics Жыл бұрын

Thanks for the appreciation. You've written direct bandgap at both places. I have explained this in the start of the video.

@nayadabdallah9917 Жыл бұрын

@@SAYPhysics sorry for the mistake. You can also check this reference: "10.1021/acs.jpclett.8b02892". I am just trying to figure it out who is right in the scientific community 🥴

@SAYPhysics Жыл бұрын

It seems you are confusing two different things i.e. y and the power of αhν. In a Tauc plot, which is a plot of (αhν)^2 versus the photon energy (hν), where α is the absorption coefficient and hν is the photon energy, a direct bandgap material exhibits a linear portion with a steep slope near the bandgap energy. Here y=(αhν)^2, to get α, we take square root of both sides so y become y^1/2 for direct bandgap and vice versa. Thanks

@MuhammadIsmail-gx9ko 2 жыл бұрын

Gravitational waves per ap k vedio hay YT may?

@SAYPhysics 2 жыл бұрын

Yes. It's in 3 parts. Link to the first part is here kzfaq.info/get/bejne/j7CbfpifyrmaYmQ.html. See rest of the parts yourself. Thanks

@jananishankar6473 5 ай бұрын

How to find absorbance using reflectance

@SAYPhysics 5 ай бұрын

You will have to use the Kubelka Munk function. I have explained this in the following video. Thanks kzfaq.info/get/bejne/j7-GoqphtJmUk30.html

@carlatenorio3490 8 ай бұрын

How does concentration affect the result of the bandgap?

@SAYPhysics 8 ай бұрын

To assess the effects of concentration on bandgap determination, it is essential to carefully prepare and analyze samples, consider correction factors (for example, Concentration-Dependent Absorption Intensity, Exciton Interactions, Saturation Effects, and Multiple Absorption Processes), and, if possible, perform measurements at different concentrations. Additionally, modeling techniques that account for exciton interactions and other concentration-dependent phenomena can be employed for a more accurate interpretation of the UV-Vis spectrum. Thanks

@carlosalmanza893 2 жыл бұрын

Excellent

@SAYPhysics 2 жыл бұрын

Thanks

@Harsh-vu8yc 2 жыл бұрын

How to determine "l" if the sample is powder in nature?

@SAYPhysics 2 жыл бұрын

In case of an opaque sample, DRS is utilized which I'll cover in the forthcoming video. Thanks

@khushboosharma3632 2 жыл бұрын

many thanks

@SAYPhysics 2 жыл бұрын

Welcome dear

@anandsp1179 Жыл бұрын

Awesome sir awsome

@SAYPhysics Жыл бұрын

Thanks for the appreciation dear 😊

@kostaskouvelis2280 7 ай бұрын

I ve got a question. In this case, when you find x - intercept value, the y axis has a negative value. Should y axis value be zero? Maybe if you extrapolate the linear part which is parallel to x axis and find the point of intersection

@SAYPhysics 7 ай бұрын

Yes. The y-axis must be zero, as explained in the presentation section at the start. Thanks

@kostaskouvelis2280 7 ай бұрын

@@SAYPhysics I am trying to get familiar with UV -Vis analysis so i have so many questions. What happens when tauc plot has 2 linear parts? So you dont know which one corresponds to band gap energy

@SAYPhysics 7 ай бұрын

@kostaskouvelis2280 in that case the bandgap will be of dual nature both direct and the indirect. Thanks

@letseat1098 2 жыл бұрын

Sir Effect of band gap on power conversion efficiency ?

@SAYPhysics 2 жыл бұрын

Actually, the energy converted is the energy corresponding to the band gap. Rest of the photon energy is simply a waste in the solar cell as heat. Solar cells operate on the solar spectrum to extract energy. The Shockley-Queisser equation puts a theoretical limit on the efficiency of single-junction solar cells (meaning, a definite single value for the band gap energy). Detailed calculations yield a curve of limiting efficiency (single junction, AM=1.5), which show two peaks. The larger peak is at a band gap of 1.34 ev yielding a limiting efficiency of 33.7%. The smaller peak occurs for band gap energy of about 1.1 ev giving an efficiency limit of nearly 32%. That is close to the band gap of silicon, currently the most popular material. Thanks

@darfaheem6237 2 жыл бұрын

How can we guess which is good fit , to go through

@SAYPhysics 2 жыл бұрын

If you're talking wrt to this video, the best line will be to the one which has overlap with most of the linear portion of the curve. Generally, for the best fit, the linear regression R2 value close to 1 gives the best fit. Thanks

@user-if1hs4xw4e Жыл бұрын

Thanks for great video! I have a one question. I've heard that UV-visible spectroscopy requires liquid sample, and actually Beer-Lambert law considers sample's concentration. Then, how can we use this for semiconductor sample?

@SAYPhysics Жыл бұрын

Yes, you're right. We can find the concentration with BL law from a liquid sample only. This I have explained in the following video kzfaq.info/get/bejne/qZpnq7Cgq5_DqHk.html However, we can find the bandgap of both liquid or solid transparent samples. In the case of opaque/reflecting samples, we can utilize reflection mode or DRS for finding the bandgap. Thanks

@kunsahaho607 2 жыл бұрын

alpha=2.302A(cm) work for thin films if we need to calculate band gap of semiconductor thin films

@SAYPhysics 2 жыл бұрын

Yes, you can use it. The thickness of film can be used as the thickness here. If the substrate will also be absorbing in that range then that thickness will also be added. For details, please see the following article. Thanks www.mdpi.com/1420-3049/17/9/10000/pdf

@physicswithsyedadilshah2786 2 жыл бұрын

Awesome explanation Sir, Can we use this for gold or silver nanoclusters? Looking for kind response.🌹

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation. Yes, you can use it. Thanks

@physicswithsyedadilshah2786 2 жыл бұрын

@@SAYPhysics Thank you Sir. Jazak ALLAH

@utaiyachandran 2 жыл бұрын

how to calculate I and Io values sir

@SAYPhysics 2 жыл бұрын

You don't need to. They're already in A or R values. Thanks

@muhammadnisarqasim636 2 жыл бұрын

sir why we draw the tangent.

@SAYPhysics 2 жыл бұрын

Inorder to find the x-intercept for the energy value. Thanks

@hkouyang 2 жыл бұрын

you are a legend

@SAYPhysics 2 жыл бұрын

Thanks dear

@anandsp1179 Жыл бұрын

Gud evening sir, could you tell us, how to convert transmittance value to absorption value

@SAYPhysics Жыл бұрын

To convert transmittance into absorbance in the case of UV-Vis data, you can use the following equation: Absorbance (A) = -log10(T) where: A is the absorbance, T is the transmittance. The negative logarithm of the transmittance is taken to convert it into absorbance. The absorbance scale is logarithmic, which means that as the absorbance value increases, the sample absorbs more light. Here's a step-by-step guide on how to convert transmittance values into absorbance: Obtain the transmittance values from your UV-Vis spectrophotometer measurements for the desired wavelengths. Calculate the absorbance by applying the equation A = -log10(T) to each transmittance value. Repeat the calculation for all the transmittance values obtained from your UV-Vis data. Note: The equation assumes that the light path length and the solvent used are constant for all measurements. Also, it's important to keep in mind that absorbance values are often reported as positive numbers, even though the equation includes a negative sign. Thanks

@mathagroups2865 Жыл бұрын

Thank you so much sir. You have mentioned l =1 it's only thin film or nanoparticles I want to calculate bg for NiO nanoparticles..can I use L value 1

@SAYPhysics Жыл бұрын

You may approximate is to 1. The value of A depends on several factors, including the nature of the semiconductor material, the size and shape of the nanoparticles, and the measurement conditions. A can be affected by factors such as the density of states in the conduction and valence bands, the bandgap energy, the effective mass of the charge carriers, and the dielectric constant of the material. In general, A is not directly related to the size or shape of the nanoparticles, but rather to the intrinsic properties of the material itself. However, the absorption coefficient can be influenced by the size and shape of the nanoparticles through the quantum confinement effect, which can cause changes in the bandgap energy and the density of states. Overall, the value of A in the Tauc equation is a material-dependent constant that is determined by the intrinsic properties of the semiconductor material and can be affected by various factors, including the size and shape of the nanoparticles. Thanks

@mathagroups2865 Жыл бұрын

Thank you so much sir

@mathagroups2865 Жыл бұрын

You are saved many research scholars 🙏💐💐 Thank you so much sir 🙏

@SAYPhysics Жыл бұрын

You're welcome dear

@SAYPhysics Жыл бұрын

This is my motivation to do more when I hear such an appreciation. You may share it with others so that majority is benefitted. Thanks

@umadevitunga8180 2 жыл бұрын

Hello sir As I understood absorption coefficient formula is (2.302/d)*A per cm, but you did directly with formula 2.303*A per cm,please clarify which is right. Thank you

@SAYPhysics 2 жыл бұрын

d is 1 cm here. In the previous video of band gap energy calculation, I have done it in detail. Thanks

@aunimardhiah4767 2 жыл бұрын

@@SAYPhysics Hi, I'm also confuse with this. Shouldn't it be multiply with column A instead of B?

@SAYPhysics 2 жыл бұрын

d is 1 cm here. In the previous video of band gap energy calculation, I have done it in detail. Thanks

@dollyarthiya7661 Жыл бұрын

how to insert f(x)?

@SAYPhysics Жыл бұрын

I'm not getting your question. What's f(x)? Thanks

@vidhyas3242 2 жыл бұрын

First of all thanks a lot for this video... sir what if the band gap increases ?whether it is crt or not... bcoz.. I was plot my graph but I got more than 5ev ...

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear. It depends on the nature of the dopant, whether it narrow or widen the bangap. You'll have to check about the energy diagrams of your host and dopant materials. Thanks

@neelakrishnan5903 Жыл бұрын

What is the range of bandgap any reference sir

@SAYPhysics Жыл бұрын

Please check the video description of this video, there you will find many relevant references. Thanks

@gustavopesadogomez8066 2 жыл бұрын

THANKS

@SAYPhysics 2 жыл бұрын

Welcome dear

@kseniia4138 2 жыл бұрын

thanks a lot for the video! i don't understand one thing... like I used to apply Beer-Lambert law to figure out the concentration of the sample for instance, and here in the equation the concentration kinda neglected at all either in others videos about Tauc Plot. I have a feeling it's because the concentration is a constant during all the measurement, but I might be wrong. Please, could you make that thing clear for me? Thank you in advance.

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear. It's a single plot with one constant concentration. To measure concentration from the absorbance data, I'm about to upload the next video.

@chaudry123 2 жыл бұрын

Nice.

@SAYPhysics 2 жыл бұрын

Thanks

@sarikasasidharan8915 2 жыл бұрын

Sir, the vedio is quite interesting, but you should adjust the Y axis in such a matter that it start from zero, other wise the band gap obtained is incorrect.

@SAYPhysics 2 жыл бұрын

@MrMuataz72 2 жыл бұрын

Excuse me, we have (2601) in our scientific center. In respect to absorbance: 1) Should we substract the values of glass data from films data? or the instrument does it? 2) The maximum value is four, why not one? Should we divide data on four?

@SAYPhysics 2 жыл бұрын

It seems that you are having 'UV 2601 UV-VIS Double Beam Spectrometer', then it means in one beam, you'd have placed the glass with thin film and in the other beam (reference), you'd have placed uncoated glass. 1) If this is the case, you don't need any subtraction of the glass as the machine would have done it. 2) Intensity doesn't matter, unless you're comparing with other samples. You can normalize your data to 1. Just keep y=0 when drawing the slope. Thanks

@MrMuataz72 2 жыл бұрын

@@SAYPhysics Thank you very much, Maybe my colleague does it wrongly, she first puts the uncoated glass, then puts the coated one separately, not at the same time as I understood from your response.

@SAYPhysics 2 жыл бұрын

@معتز سعدي بدري عبد الدليمي We usually do this method for a single beam equipment, thereby subtracting the uncoated from the coated one, which is not very accurate for critical samples but does the job. For a dual beam, we may follow the procedure, as I suggested earlier. Thanks

@MrMuataz72 2 жыл бұрын

@@SAYPhysics ❤❤❤

@anhngoc6310 2 жыл бұрын

thanks

@SAYPhysics 2 жыл бұрын

Welcome dear

@roboticscience4627 2 жыл бұрын

Sir plz make a video on Psi and Delta graph of from ellipsometer data.. Plz ❤️

@SAYPhysics 2 жыл бұрын

Noted. Thanks

@ann439 Жыл бұрын

hi thank you for the great video, but i couldnt understand why alpha = 0,4343 A cm^-1 become alpha = 2.302 cm^-1. looking forward for answer, thanks :)

@SAYPhysics Жыл бұрын

Thanks for the appreciation dear. I have explained it at 3:14 that 0.4343 is the value of log(e). Thanks

@amirovshaxboz 2 жыл бұрын

👏👏👏

@dashnetaha3576 2 жыл бұрын

Thank you

@SAYPhysics 2 жыл бұрын

You're welcome

@dashnetaha3576 2 жыл бұрын

Teacher I have a questions how we solve questions like that determine the attenuation light absorbed by silicon slab thickness of 0.01 absorption coefficient of Si is 1.5 cm_1 incidence intensity was about 175 watt/m^2

@SAYPhysics 2 жыл бұрын

In my forthcoming video in few days, I'll be explaining this in terms of finding the concentration. Thanks

@angelicafreitas941 Жыл бұрын

(ahv)^1/n = A(hv-Eg) and (ahv)= A (hv-Eg)^n both are Tauc equation according to literature...but these equations are similar just if A = 1....I am confused about that....Tauc plot is used just for amorphous materials?? But why is used for TiO2 and other materials??

@SAYPhysics Жыл бұрын

Yes Angelica, you're right that Tauc's eq. can be written in both forms, which are the same excluding A. A is a proportionality constant, which is playing its role in the equation (and depends on some geometrical/physical parameters). However, in calculation of the bandgap, it is not playing its role, as I have explained it in the start of the tutorial i.e. y=0 in the equation, and hence 0/A=0. You're again right that Tauc used this eq. for amorphous material. However, it can be used for disordered s/cs as well. Consult the this link and the references there in for more understanding. Thanks en.wikipedia.org/wiki/Tauc_plot

@angelicafreitas941 Жыл бұрын

@@SAYPhysics Thanks for explanation!!!!

@ankithamenon8398 Жыл бұрын

is the value 2.3 fixed?

@SAYPhysics Жыл бұрын

Yes, if you're using a standard cuvette. Thanks

@ankithamenon8398 Жыл бұрын

@@SAYPhysics irrespective of the concentration too?

@SAYPhysics Жыл бұрын

Yes, it's based on the geometry as I explained in the start of the tutorial. Thanks 👍

@suunguyen9458 2 жыл бұрын

you have wrong bandgap on the graph, y-axis starts at 0, meanwhile you make y-axis negative, because y=0 then E=hv

@SAYPhysics 2 жыл бұрын

Yes, you're right. The y-axis must be selected from 0 while drawing the slope. However, the bandgap is right as it make a difference of 0.05 eV which again rounds up to 5.6 eV. Thanks for the input.

@katarzynaungeheuer7771 Жыл бұрын

I wanted to point out the same thing. The band gap should be read from y=0. Here it does not make a big difference but many could be misleaded.

@SAYPhysics Жыл бұрын

Yes, you're right. In other such videos, I've explained this in more details. Thanks for your input. Thanks

@dalalalhilfi87 Жыл бұрын

From the hypothesis, the thickness of the membrane enters the alpha calculations

@SAYPhysics Жыл бұрын

Somehow you are right. Please watch this video tutorial to have a deep understanding of this. Thanks kzfaq.info/get/bejne/qZpnq7Cgq5_DqHk.html

@boron1010 10 ай бұрын

why y=0?

@SAYPhysics 10 ай бұрын

I've explained this in the presentation section of the video. Thanks

@user-gz5zy1ve3o 2 жыл бұрын

why did you put 1cm as l? I think it should be thickness of sample not 1cm

@SAYPhysics 2 жыл бұрын

Yes, you're right, it's thickness of the sample, which I have mentioned. For a solution, the cuvette internal dimensions (sample thickness) is 1 cm. Thanks

@user-gz5zy1ve3o 2 жыл бұрын

@@SAYPhysics thanks for your answer. I have another question. Why do we use cm as a unit of tauc plot?(ie, cm-1 eV). If we use m not cm, slpoe of linear region of tauc plot gets bigger and X intersection(optical band gap) gets also bigger. So I wonder whether there is certain reason or meaning for using cm.

@SAYPhysics 2 жыл бұрын

@@user-gz5zy1ve3o The peaks (like in FTIR) are very well resolved when we use the wavenumber in cm-1 on the x-axis. However, here on the y-axis, there are no technical reasons. But in Physics, whenever we deal with coefficients (length dependent), we usually use cm. Thanks

@user-gz5zy1ve3o 2 жыл бұрын

@@SAYPhysics thank you Sir 😊

@ismailhossain3815 2 жыл бұрын

good,,, can anyone give me the personal details of this teacher?

@SAYPhysics 2 жыл бұрын

Thanks dear Dr. Shahid Ali Associate Professor (Tenured) Department of Physics, University of Peshawar 25120 Peshawar, Khyber Pakhtunkhwa, Pakistan facebook.com/sayphysics sayphysics@gmail.com kzfaq.info/love/vmhJBxOCFE9Ehv137EJKt scholar.google.com.pk/citations?user=Fr57EToAAAAJ&hl=en www.uop.edu.pk/departments/Teaching-Faculty/?r=1190&q=Dr-Shahid-Ali

@ismailhossain3815 2 жыл бұрын

@@SAYPhysics Thanks sir,,,, I'm a regular viewer of your videos,,,,, Take love 💕💕💕 from Bangladesh

@SAYPhysics 2 жыл бұрын

Thanks for the appreciation dear brother. The same love and feelings from Pakistan. I'll appreciate you inform your friends and classmates regarding the channel. Thanks again

@jeanfrancesegbuhuzor7063 7 ай бұрын

Now following. Thank you for your videos.