Band offset determination of the GaAs/GaAsN interface using the DFT method

TL;DR

This paper presents a first-principles method to determine band offsets at the GaAs/GaAsN interface, successfully applying it to both known and challenging systems, and analyzing strain effects on band alignment.

Contribution

It introduces a DFT-based approach for interface band offset calculation and demonstrates its effectiveness on GaAs/GaAsN systems, including strain influence.

Findings

The method accurately predicts band offsets consistent with experiments.

Strain significantly affects the band lineup, switching from type I to type II.

The approach is validated on a well-known superlattice system.

Abstract

The GaAs/GaAsN interface band offset is calculated from first principles. The electrostatic potential at the core regions of the atoms is used to estimate the interface potential and align the band structures obtained from respective bulk calculations. First, it is shown that the present method performs well on the well-known conventional/conventional AlAs/GaAs (001) superlattice system. Then the method is applied to a more challenging nonconventional/conventional GaAsN/GaAs (001) system, and consequently type I band lineup and valence-band offset of about 35 meV is obtained for nitrogen concentration of about 3 %, in agreement with the recent experiments. We also investigate the effect of strain on the band lineup. For the GaAsN layer longitudinally strained to the GaAs lattice constant, the type II lineup with a nearly vanishing band offset is found, suggesting that the anisotropic strain along the interface is the principal cause for the often observed type I lineup.