Dear Researchers,
The literature data available for III-Nitride properties have great differences in the values of various parameters.
I am searching for electron affinity values of III-N alloys.
What could be the most accurate values for electron affinities and the bowing parameter for InGaN and AlGaN alloys?
Thank you.
Dear Avinash,
I suspect you are looking into the wurtzite polytype of the nitrides.
1) In this case, band gap bowing parameters can be found here for InGaN:
Article Dielectric function and Van Hove singularities for In-rich I...
and for AlGaN:
Article Anisotropic optical properties of semipolar AlGaN layers gro...
The main uncertainties stem from the fact that these materials are wurtzite and thus anisotropic. Especially for AlGaN this means that the lowest energy band gap is not the same over the whole concentration range. Consequently, you cannot describe it by a simple bowed band gap for the whole range but you have to take into account at least crystal field splitting and spin-orbit coupling. The above references are of course considering this fact.
2) The electron affinities are a different story. Basically, electron affinities are a surface property not a bulk property, different surfaces have different affinities; therefore you should exactly describe your intended usage.
If you want to obtain band offsets between different nitride materials, I propose to use an empiric 60%/40% or 66%/34% rule for conduction band vs. valence band offsets instead of more complicated route via affinities and doping levels.
Best regards,
Martin.
