[Wien] (no subject)

[Oleg Rubel]

The short answer is: It should be a fully-relaxed structure of GaN 
(wurtzite).

A longer answer is: One should think on how the polarization will 
manifest itself in experimental situation and select two structures 
(lambda_0) and (lambda_1) accordingly. If you are interested in 
group-III/N LED, the buffer is GaN (lambda_0). The quantum well is a 
(In,Ga)N solid solution (lambda_1), which is epitaxially strained on 
GaN. A difference in polarization between two structures will lead to an 
electric field withing the quantum well. So, in this case, it will be 
incorrect to ask a question: What is the spontaneous polarization of 
GaN? or What is the polarization of (In,Ga)N? What matters is the 
difference only.

I hope this will help.

Oleg

-- 
Oleg Rubel (PhD, PEng)
Department of Materials Science and Engineering
McMaster University
JHE 359, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada
Email: rubelo at mcmaster.ca
Tel: +1-905-525-9140, ext. 24094
Web: http://olegrubel.mcmaster.ca

On 2018-Jun-09 03:24, Harzellaoui Abdelkader wrote:
> hello
> I tried Berrypi's accompanying code and exactly the GaN  tutorial4. my 
> question is how to create the GaN_W structure. because I see that it is 
> important if I want to calculate the polarization or phase of another 
> structure. Thank you
> 
> 
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