Refractive index (n)and film thickness(t) we can calculate by making envelope on transparent curve..

n = [N + (N2 – ns2)1/2]1/2,

N = (ns2 +1)/2 + 2ns (Tmax -Tmin)/ Tmax.Tmin

and t = λ1λ2/ 2[n1 λ2 – n2 λ1]

where n1 and n2 are the refractive indices at the two adjacent maxima (or minima) at λ1 and λ2, ns is the refractive index of the substrate, Tmax and Tmin are the transmittance values for a given wavelength taken from the envelopes....let me know if u hv any doubt

Can refer Perkin elmer application note on UV VIS spectra they have it

Refractive index (n)and film thickness(t) we can calculate by making envelope on transparent curve..

n = [N + (N2 – ns2)1/2]1/2,

N = (ns2 +1)/2 + 2ns (Tmax -Tmin)/ Tmax.Tmin

and t = λ1λ2/ 2[n1 λ2 – n2 λ1]

where n1 and n2 are the refractive indices at the two adjacent maxima (or minima) at λ1 and λ2, ns is the refractive index of the substrate, Tmax and Tmin are the transmittance values for a given wavelength taken from the envelopes....let me know if u hv any doubt

The previous method is valid for relatively thick films, showing several interference fringes or at least 2 maxima.

Using the fresnel equations you are able to determine the thickness of your film by adjusting the refractive index and thickness by a least squares fitting.

Dear Carlos batista,

Can you please give more details or give a reference that will help; my e-mail is [email protected]. best regards

hi folk

Please give all response here it'll be more helpful for all.

tnx

Hi Varun Chaundhary

Your comment is very helpful and i calculate film thickness based on equation what you mentioned above and also i gave the sample for ellipso for finding thickness and i want to check my value with that.I have one more doubt some cases of my transmittance spectra i didn't get any maxima and minima for that cases what can i do?

hi Dhivya

Tnx... we can't calculate film thickness by this formula if interference fringes are not available..Than we have to think on Carlos Batista method.....

Hi Batista,

plz give more detail ............

Tnx

Hi Bastista

please give detail about film thickness calculation

Thanks

hi Dhivya

plz mention ur e-mail. i will send u the paper for calculating n & t by swanepoel method(for both case)

Hi Muhammed ALI

Thank you. My mail id is [email protected]

hi Ali,

plz send me same on the following address

[email protected]

tnx a lot

High ALI, please send me the same paper for calculating n and t, e-mail : [email protected]

thank you very much;

Hi all, tell me the calculation for thickness measurement for films not having interference fringes.

I refered one paper in which swanepoel method is used (for non interference fringes transmission curve) by taking the minimum lambda as Transmission minima.

They have caluculated thickness everthing. I dont think whether it is right or wrong. Please tell me.

Thanks

Read the book of O. S. Heavens: Optical properties of thin films. On pages 74-80 one can find many special applications that follw from the matrix method. Swanepoel and Manifacier methods are only approximations. In the mentioned book you may find the exact formulas.

Dear sir

Can u send some journal material regarding the measurement of optical constant from linear transmission curve

What do you mean by "linear transmission curve"? What optical constant do you mean? n, k or else?

If you send me your email I could send you the above mentioned book of O.S. Heavens.

Dear Sir,

I would like to read this book so kindly send me on following address..

[email protected]

Thanking you

Thanks sir

my email id is

[email protected]

i meant the transmission curve without any interference fringes.

i did swanepoel method calculations for the transmission curve having interference fringes.

But i do not know how can we implement the swanepoel method for the transmission curve that are not having the interference pattern.

Interference fringes are recorded when the film is sufficient thick. If the film is thin (~100 nm) no fringes appear in the VIS-UV region. The Manifacier approach cannot be applied and one has to fit the whole curve taking into account the lambda dependence of n and k.

Then you have to apply the general formula, given in the book, and fit the transmission data.

Use a linear dependence of k and n on the wavelength and fit the curve with 5 parameters: 2 for k, 2 for n and the thickness.

What is your film and the substrate?

Dear Sir

I'm working in ZnO and my substrate is Glass

Dear Sir

Kindly send one copy of your book by O.S.Heavens. My e-mail address is

[email protected]

Hi friends please send the details about the calculation of activation energy and please explain the details about the impedance studies....

Hi varun choudry thanks for your thickness formula.... I want to know the calculation for activation energy please send....

hi varun , divya , carlos batista and michael kompitsas and everyone ........ the conversation topic is very much useful for me as i am new in this field . so thnx to all you.

if possible pls send the a copy of swanepoel method ref and O. S. Heavens book.

my email. id is [email protected]

also thnx to Richard Dluhy for his references.

Hi, find below a link to a thesis chaper where all is very well explained:

http://wwwae.ciemat.es/~mfg/thesis/chapter5.pdf

Some more details on the following paper:

http://144.206.159.178/FT/1035/11716/237109.pdf

By considering a single layer on a semi-infinite substrate with theoretical T and R curves you must minimize the difference of theoretical and measured curves:

|T - Tmeasured|^2 +|R-Rmeasured|^2 = 0 (least squares)

You can do this easily in MS excel with solver function, just chose what cells to change (refractive indices and thickness on the theoretical functions) to get the best fit (minimal difference between theoretical T and R and Tmeasured and R measured)

Voila! pay attention to the imputs (starting values) or else you can get divergence on getting the solution.

Hope this will help.

Regards,

Carlos

Hi Ali,

Iam , also interested in this paper. Please, could you send a copy of the paper to this e-mail address : [email protected]

thanks

Hi Mohamed Ali,

I m selvi want the copy of swanepoel method pls send it to my mail: [email protected]

Hi Muhammed ALI,

I want help, please send me the paper for calculating n & t by swanepoel method to this e-mail adress : [email protected]

thanks.

What a terrific site plenty of papers you provided mi dear Carlos Batista!

Many thanks!

In some paper based on swaneopoel method they calculated one quantity called optical conductivity. What is it ? is it same as electrical conductivity?

Here is a simple formula to relate thickness to index:

d= (delta m)/ (2*(n^2 - cos^2 (theta))^.5 * delta v))

d=thickness

delta m= number of fringes (humps) which can be clearly counted from the %T spectra.

n= index of refraction

theta = incident angle of light

delta v= the range of frequencies (in wavenumber actually) over which delta m was counted.

Ref: N. J. Harrick, “Determination of refractive index and film thickness from interference fringes.,” Applied optics, vol. 10, no. 10, pp. 2344-9, Oct. 1971

I have a signal that is unrectified. Now I want to create an upper and a lower envelope that will join the local maxima and minima respectively. Now I have a list of all the local extrema.. How can I create a spline that will join all the maxima

I know and I have parav program. But I want my own program. My problem is how to draw the envelope with matlab. I want help.

Thanks.

Varun, could you please give me the reference of the equation which relates thickness and refractive index?

Dear Madam

I need to search exact referance so up to that time you can see this one

Y.U. Ahn et al. / Materials Letters 57 (2003) 4660–4666

thanks

v

Thank you!

You con measure quickly with a monocromatic source of frecuency f. I suppose that the film is parallel plane and that you have a good nonius to measure angles. You have to iluminate and collect the transmited or reflected (best) ray with a lens and to focus in a screen. Move the been and look for the maximun of intensity. Point that angle, a1. After that, move the beam so that the angle raise, and look for the another maximun of intensity. Point this new angle a2. The thickness d is:

d= (squareroot((na/n)^2-(sina2)^2)+squareroot((na/n)^2-(sina1)^2)/(2*na*f*((sina1)^2-(sina2)^2

where na and n is the refraction index of the surrounding medium (perhaps air) ant of the film, respectively.

This is a gross method. look how deal with the Fabry-Perot interferometer. Is like that but with best accuracy. And if you have a good espectometer i recomended to build a interference filter.

Sir please give the details calculation of optical absorption, esr and ftir of glass system

Can't you just measure the optical band-gap from a Tauc Plot? It works mostly for amorphous solids but corrections exist for polycrystalline structures. If you have transmittance and reflectance spectra, you can find the absorbance, the Kubelka-Munk function will give you F(R)=(1-R)^2/2R, where R is the reflectance. Then plot (F(R)*hv)^x vs hv, where hv is the light energy and x=1/2 for an indirect bandgap material and 2 for a direct bandgap. The bandgap is found by extrapolating a line from the flat part of the curve to the x-axis, and reading the x intercept.

I want indication to solve numerically the system of equations (Tmax, Tmin) in the case of film thickness non unifome

I applied the method of Swanepoel for a film nonhomogeneous in thickness. the problem is that for some thin films the experimental spectrum is reprodictible but for others it is not possible despite the presence of fringe. I want an explanation and clarification?

Thank you!

Look at :

J C Manifacier et al 1976 J. Phys. E: Sci. Instrum. 9 1002 doi:10.1088/0022-3735/9/11/032 and cited papers (a lot of them). May be it will be useful for you.

I can not find it, if you have this article, please send it to this address [email protected]

Thank you Maxim Khazimullin.

If you need a reference, here is a good one: http://dx.doi.org/10.1364/AO.17.002779

The title of the paper is: Optical interference method for the approximate determination of refractive index and thickness of a transparent layer

Hello,

I need some detailed documentation for the calculation of the transmission for a thin film. Thank you to send to the following e-mail : [email protected]

Can you download the folowing file? If you are not succesful I will try to mail it.

thank you very much "Ruth Diamant". Download.

Read the following reference] ; Serdar Aydin et al. Investigation of Structural, morphological and optical properties of electrodeposited SnO2 films International Journal of the Physical Sciences 7(2012)5327-5333

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For this kind of question, try to read our following article. I think that will be useful for your job :

Determination of layer thickness and optical constants of thin films by using a modified pattern search method. Optics Letters 02/2012; 37(4):449-51.

You can find answers to your question by looking for different answers to the question of Dr. Azzedine Dehbi-Alaoui:

"Is there any free software that can calculate optical constants from thin films reflect and/or transmetance spectra data"

Dear M. Kechouane: whem you post a reply that points to another thread inside ResearchGate, it would be a good idea to include its URL.

Greets.

Dear A. Tiburco-Silver,

sorry for this oversight. Here is the link:

https://www.researchgate.net/post/Is_there_any_free_software_that_can_calculate_optical_constants_from_thin_films_reflect_and_or_transmetance_spectra_data?cp=re65_x_p2&ch=reg&loginT=M22FLF7eDrmTF8dW0HzTqqHq-HCCWfeinaQyeIJ0AIA%2C&pli=1

Greetings

The present days good technique for optically measuring film sicknesses is ellipsometry based on the polarization state change of reflected light at various incident wavelengths. It works down to the nanometre scale up to the micrometre scale.

Here is an excellent tutorial : http://www.jawoollam.com/tutorial_1.html

If anyone can highlights me to use a numérical method for PL spectra from doped and non doped III-V semiconductor?

To simulate one .please advise me, just to compare it to experimental results.

using Beer–Lambert law we can calculate the thickness of film but before that we have to know or calculate ε (molar absorbtivity).

As you are interested in measuring band gap of your films, I would suggest you to measure thickness by optical/mechanical profilometer or by ellipsometer.Then use the calculated thickness for determining the band gap. You can use Tauc plot technique (ahv Vs photon energy (hv) plot with your transmittance or absorbance data) to calculate band gap of your thin films. This will definitely work.

Dear Charles Hirlimann, ellipsometry works if you have your film(s) deposited onto a reflecting surface. If your film(s) are deposited onto a transparent substrate (as this is the case for films aimed to be used as transparent conducting coatings), ellipsometry does not work. Amazingly, the author of this thread has never said anything concerning this very important point. It seems that there are some guys that think we are a kind of mentalist.

You can calculate the thickness from a T spectra using the interference fringes (it depends on the substrate and film's thickness). For an accurate determination, you can use the PUMA software, download it at: http://www.ime.usp.br/~egbirgin/puma/

Varun, How can I draw envelopes?

Varun, How can I draw envelopes? please reply me on my email address; [email protected] Thanks

Absorption spectra