Atomistic tight binding study of quantum confined Stark effect in GaBixAs1−x/GaAs quantum wells

Abstract

Recently, there has been tremendous research interest in novel bismide semiconductor materials (such as GaBixAs1−x) for wavelength-engineered, low-loss optoelectronic devices. We report a study of the quantum confined Stark effect (QCSE) computed for GaBixAs1−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 (). 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 (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 previously observed 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 GaBixAs1−x/GaAs QWs, and will be important for the design of devices in the optoelectronics and spintronics areas of research.