Ellipsometric study of the Electronic Structure of GaMnAs and LT-GaAs

TL;DR

This study uses spectroscopic ellipsometry to analyze how Mn doping affects the electronic structure of GaMnAs, revealing shifts in critical points linked to impurity band interactions.

Contribution

It provides detailed optical constant measurements and critical point analysis of GaMnAs, highlighting the effects of Mn doping on its electronic structure.

Findings

E1 critical point shifts to higher energies with increased Mn doping

Other critical points remain unaffected by doping

Band gap renormalization and sp-d hybridization influence the electronic structure

Abstract

We have measured the optical constants of GaMnAs from 0.62 eV to 6 eV, using spectroscopic ellipsometry. The second derivatives of the dielectric function are examined through a critical point analysis. The E1 critical point shifts to higher energies with increased doping of Mn, while all other critical points appear unaffected. The evolution of the critical points results from the interplay between band gap renormalization from ionized impurities and sp-d hybridization of the Mn induced impurity band and GaAs valence and conductions bands.