Half-occupation approach for the ab initio calculation of strained Ga(AsSb)/GaAs valence band offsets

Maria J Weseloh,Stephan W Koch,Jan Oliver Oelerich

doi:10.1063/5.0001300

Abstract

An ab initio based scheme for the determination of the valence band offset between different III–V semiconductor systems is presented on the example of GaAs and Ga(AsSb) pseudomorphically strained to GaAs for Sb concentrations up to 37.5%. Modified core-to-valence band maximum calculations are used in combination with the half-occupation technique. The valence band offsets between GaAs and Ga(AsSb) are needed for the predictive design of optically active quantum well heterostructures emitting in the near-infrared region of the electromagnetic spectrum.

Highlights

Near-infrared lasers with good emission properties are important, e.g., for applications in telecommunication, optical data transfer,1 or medicine.2 Since the often employed type-I heterostructure systems suffer from significant Auger losses,3 type-II configurations with potentially suppressed Auger recombination may offer a promising alternative
Since each layer in the heterostructure is assumed to retain its individual bandgap, the critical parameter needed for the band matching across the heterostructure is the offset of the respective valence band maxima (VBM)
For the GaAs/Ga(AsSb) interface, we show that the DFT-1/2 corrections are required to produce meaningful results for the valence band offset (VBO), which agree well with experimental data

Summary

Introduction

Near-infrared lasers with good emission properties are important, e.g., for applications in telecommunication, optical data transfer, or medicine. Since the often employed type-I heterostructure systems suffer from significant Auger losses, type-II configurations with potentially suppressed Auger recombination may offer a promising alternative. Examples are the so-called “W” structures employing (InGa)As and Ga(AsSb) quantum wells grown on a GaAs substrate.. Examples are the so-called “W” structures employing (InGa)As and Ga(AsSb) quantum wells grown on a GaAs substrate.4 These configurations have the advantage that both electrons and holes are strongly confined in separate layers, but the wavefunction overlap is large enough to allow for strong optical gain. Since full ab initio calculations for the entire heterostructures are numerically extremely demanding, the currently most employed scheme is the so-called envelope function approximation.5 For this purpose, one uses the respective bulk bandstructure for the in-plane energy dispersion of the individual layers, whereas perpendicular to the planes, i.e., in the growth direction of the heterostructure, the plane-wave envelopes of the Bloch wavefunctions are replaced by the quantized confinement functions. The valence band offset (VBO) becomes a decisive parameter for designing a heterostructure, since the band alignment determines carrier confinement and transport properties

Methods

Results

Conclusion