A Change of ε with pressure for Semiconductors

[IWantToLearn]

In "Sado Adachi" book "Properties of Group-IV, III–V
and II–VI Semiconductors" page 222, he reported that "both ε_s and ε_∞ decrease almost linearly with increasing pressure", however i was not able to find any empirical formula to describe these relationship for materials InAs, InP, InSb, where can i find these relations?

 

[Cybertib]

In general, I would find the effect of material-dependent pressure on the optical properties of materials by two ways.
(i) It can be computed from first principles using Density Functional Theory.
(ii) There are also some experimental measurements which propose some fitted functions for a description at equilibrium, let's say.
In general, the effect of pressure may be a transient effect, which means that non-equilibrium can make you reach a state of matter which was not observed experimentally so far.
Would you have access to scientific literature, maybe? http://scholar.google.com would help here.

 

[Useful nucleus]

εs varies with 1/ω² , where ω is the zone center phonon mode frequency as you can find in the classic by Born and Huang. Also as you increase the pressure, ω increases because the ions get closer, the bonds get stronger, and the vibrations become faster. I do not think there is a clear-cut formula to describe pressure (p) vs. ω, but according to your statement , it should be something like √p α ω.

I do not fully understand the variation of ε∞ with external thermodynamic forces such as pressure.