Atomistic tight binding study of quantum confined Stark effect in GaBi$_x$As$_{1-x}$/GaAs quantum wells

TL;DR

This study uses atomistic tight-binding calculations to analyze the quantum confined Stark effect in GaBi$_x$As$_{1-x}$/GaAs quantum wells, revealing unconventional behavior at low Bi fractions due to Bi clustering effects.

Contribution

First atomistic study of QCSE in GaBi$_x$As$_{1-x}$/GaAs quantum wells, highlighting the influence of Bi clustering on electric field response.

Findings

Unconventional Stark shift at low Bi fractions ($x$=3.125%) due to hole wave function confinement.

Weak impact of Bi clustering at higher Bi fractions ($ ext{\%}$), resulting in quadratic Stark shift.

Insights into electric field effects on electronic and optical properties for device design.

Abstract

Recently, there has been tremendous research interest in novel bismide semiconductor materials (such as GaBi$_x$As$_{1-x}$) for wavelength-engineered, low-loss optoelectronic devices. We report a first study of the quantum confined Stark effect (QCSE) computed for GaBi$_x$As$_{1-x}$/GaAs quantum well (QW) structures based on large-scale atomistic tight-binding calculations. A comprehensive investigation of the QCSE as a function of the applied electric field orientations and the QW Bi fractions reveals unconventional character of the Stark shift at low Bi compositions ($x$=3.125\%). This atypical QCSE is attributed to a strong confinement of the ground-state hole wave functions due to the presence of Bi clusters. At technologically-relevant large Bi fractions ($\geq$ 10\%), the impact of Bi clustering on the electronic structure is found to be weak, leading to a quadratic Stark shift of the ground-state transition wavelength, similar to the previously observed Stark shift in other conventional III-V materials. Our results provide useful insights for the understanding of the electric field dependence of the electronic and optical properties of GaBi$_x$As$_{1-x}$/GaAs QWs, and will be important for the design of devices in the optoelectronics and spintronics areas of research.