EPW Forum

Dear All,
I am practicing the GaN-II example to calclate the carrier mobility. https://docs.epw-code.org/doc/GaN-II.html
The nk1(23)=12, nq1(23)=6. nkf1(23)=nqf1(23)=24.
First I use epw2.in to get the hole mobility below, the value is lower than that reported in the example but is consistent in order.
=============================================================================================
Temp Fermi Hole density Population SR Hole mobility
[K] [eV] [cm^-3] [h per cell] [cm^2/Vs]
=============================================================================================

100.000 10.9042 0.99999E+13 0.33738E-06 0.839382E+02 -0.342509E-15 -0.744586E-17
0.496390E-17 0.839382E+02 0.000000E+00
0.744586E-17 0.000000E+00 0.200098E+03
300.000 11.1934 0.10000E+14 0.27325E-06 0.358302E+02 -0.107215E-14 -0.794217E-16
0.395945E-16 0.358302E+02 0.000000E+00
-0.969503E-20 0.000000E+00 0.403252E+02

So I guess that maybe the parameters (nk1(23) nkf1(23).... ) used in epw2.in may also get a consistent (in order) value of electron mobility.
However, the obtained value using epw3.in is very low and not physically correct and not converged. I want to know whether the epw3.in setting is correct. Do I need to increase the nkf1(23) and nqf1(23) for the electron mobility calculations?

All the input and output are attached.

Many Thanks.

Hello,

You have to adapt 'ncarrier = -1E13' to 'ncarrier = 1E13' to do electron mobility
and also change the position of the Fermi level to be closer to the CBM.

I could also suggest doing the more recent tutorial from the 2021 school
https://epw2021.oden.utexas.edu/74-schedule

scroll down that page and look for the content on Wednesday.

Hope this helps,
Samuel

Thanks, Dr. Samuel,

I had checked that the ncarrier was positive in epw3.in and the input Fermi energy of epw3.in was 12.976 fsthick=0.4 eV,
The fermi level in epw3.out is : 100K 12.8212 300K 12.5964 which are close to the Conduction band minimum = 12.930649 eV

How to change the Fermi energy to a correct value, do I need to increase the ncarrier to lift the fermi level?
Thanks.

sponce wrote: ↑Mon Oct 04, 2021 1:16 pm Hello,

You have to adapt 'ncarrier = -1E13' to 'ncarrier = 1E13' to do electron mobility
and also change the position of the Fermi level to be closer to the CBM.

I could also suggest doing the more recent tutorial from the 2021 school
https://epw2021.oden.utexas.edu/74-schedule

scroll down that page and look for the content on Wednesday.

Hope this helps,
Samuel