Optical absorption spectrum in disordered semiconductor multilayers

TL;DR

This study investigates how chemical disorder affects the electronic and optical properties of semiconductor alloy multilayers, revealing layer-dependent absorption spectra and the emergence of multiple absorption bands under strong disorder.

Contribution

It introduces a theoretical analysis of disorder effects on optical absorption in multilayers using tight-binding and coherent potential approximation methods.

Findings

Absorption depends on alloy concentration, disorder strength, and layer number.

Disorder broadens the absorption spectrum and causes two bands in strong disorder.

Interior layers absorb most photon energy.

Abstract

The effects of chemical disorder on the electronic and optical properties of semiconductor alloy multilayers are studied based on the tight-binding theory and single-site coherent potential approximation. Due to the quantum confinement of the system, the electronic spectrum breaks into a set of subbands and the electronic density of states and hence the optical absorption spectrum become layer-dependent. We find that, the values of absorption depend on the alloy concentration, the strength of disorder, and the layer number. The absorption spectrum in all layers is broadened because of the influence of disorder and in the case of strong disorder regime, two optical absorption bands appear. In the process of absorption, most of the photon energy is absorbed by the interior layers of the system. The results may be useful for the development of optoelectronic nanodevices.