Approximation of excitonic absorption in disordered systems using a compositional component weighted CPA

TL;DR

This paper develops an advanced theoretical approach to model excitonic absorption in disordered alloy systems, accurately capturing effects of varying disorder and interaction strengths, and providing insights into exciton formation under different conditions.

Contribution

It introduces a compositional component weighted CPA method for excitons in disordered alloys, extending existing theories to handle variable interactions and disorder levels.

Findings

The method accurately interpolates between weak and strong disorder regimes.

It can handle site-dependent contact interactions, adding disorder complexity.

Numerical results show how exciton states evolve with interaction strength variations.

Abstract

Employing a recently developed technique of component weighted two particle Green's functions in the CPA of a binary substitutional alloy $A_cB_{1-c}$ we extend the existing theory of excitons in such media using a contact potential model for the interaction between electrons and holes to an approximation which interpolates correctly between the limits of weak and strong disorder. With our approach we are also able to treat the case where the contact interaction between carriers varies between sites of different types, thus introducing further disorder into the system. Based on this approach we study numerically how the formation of exciton bound states changes as the strengths of the contact potentials associated with either of the two site types are varied through a large range of parameter values.