Screening of the electric field in covalent crystals containing point defects

TL;DR

This paper derives an expression for electric field screening length in p-type semiconductors considering acceptor energy spread and valence band tail effects, highlighting the dependence on carrier density and mobility-to-diffusion ratio.

Contribution

It introduces a new analytical expression for screening length that accounts for energy spread and density of states tail effects in covalent crystals with point defects.

Findings

Screening length depends additively on carrier density and mobility-diffusion ratio.

Derived expression within Debye-Hückel approximation for specific semiconductor conditions.

Highlights the role of acceptor energy spread and valence band tail in screening behavior.

Abstract

An expression is derived within the framework of the Debye-H\"uckel approximation for the screening length of a field in a p-type semiconductor taking into account the energy spread of immobile acceptor levels and the density of states tail of the valence band. It is shown that the screening length depends additively on the product of the carrier density and their drift mobility to diffusion coefficient ratio (for free holes in valence band and holes hopping via acceptors).