InN dielectric function from the midinfrared to the visible range

TL;DR

This paper analytically evaluates the dielectric function of wurtzite InN across a broad spectrum, revealing singularities and their effects on optical properties, especially near the energy gap.

Contribution

It provides an analytical model of InN's dielectric function from mid-infrared to visible, including effects of degeneracy and temperature on singularities.

Findings

Real part has a logarithmic singularity at the absorption edge.

Divergence in dielectric function is smeared by temperature or relaxation.

Imaginary part exhibits a plateau away from absorption onset.

Abstract

The dispersion of the dielectric function for wurtzite InN is analytically evaluated in the region near the fundamental energy gap. The real part of the dielectric function has a logarithmic singularity at the absorption edge. This results in the large contribution into the optical dielectric constant. For samples with degenerate carriers, the real part of the dielectric function is divergent at the absorption edge. The divergence is smeared with temperatures or relaxation rate. The imaginary part of the dielectric function has a plateau far away from the absorption onset.