DC permittivity values missing for InGaAs

[Alex Valavanis]

Reported via SourceForge...

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I was analyzing an inalgaas MQW structure today, but when I tried to run the following command "qwwad_ef_band_edge --material inalgaas" I got the following "Warning: Unknown dc permittivity for InAlGaAs". I tried updating the materials-library.xml with some values I found for the static permittivity, but it didn't help. Do you have any suggestions?

I really need to compute the right values for the eps_dc.r file in order to use the Schroedinger-Poisson solver...

[Alex Valavanis (valavanisalex)]

The problem here is that the materials-library.xml file isn't actually used in many places in QWWAD yet. The qwwad_ef_band_edge program currently just uses a limited set of hard-coded values.

The proper fix will be to hook up qwwad_ef_band_edge to use the material library (see bug #1457023).

An even better fix would be to separate the permittivity calculator from qwwad_ef_band_edge because it's not really a band-structure parameter.

For now, though, if you can provide a reference to some suitable values, I can just hardcode them into the program.

[Michael Bland-Albrecht (mblandalbrecht)]

Here are some references you can use for the static (dc) permittivity:

For GaInAs: http://www.ioffe.ru/SVA/NSM/Semicond/GaInAs/optic.html (Eps rel~13.1-14.1)

For InAlAs: http://www.iue.tuwien.ac.at/phd/palankovski/node32.html (Eps rel~12.46)

[Alex Valavanis (valavanisalex)]

@Michael - I've improved support for InAlGaAs in the development version of QWWAD, and it'll be released officially in QWWAD 1.6.

You can get a copy of the development version from the daily-builds PPA [1] (if you're using Ubuntu Linux) or from GitHub [2] if you want to build it yourself.

[1] https://code.launchpad.net/~qwwad-dev/+recipe/qwwad-daily
[2] https://github.com/QWWAD/qwwad

[Alex Valavanis (valavanisalex)]

Here is a test script for calculating a bandstructure plot for the conduction band states in an InGaAs/AlInAs well.

[Alex Valavanis (valavanisalex)]

I've backported the changes to the QWWAD 1.5.2 release, which I will push shortly :)