Atomistic tight binding study of quantum confined Stark effect in GaBi _x As_1-x /GaAs quantum wells

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 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 ([Formula: see text]). 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 ([Formula: see text]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 GaBi _x As_1-x /GaAs QWs, and will be important for the design of devices in the optoelectronics and spintronics areas of research.