Influence of Growth Conditions on the Structural and Opto-electronic Quality of GaAsBi

A systematic series of GaAsBi pin diodes was grown by MBE using different growth temperatures and Bi fluxes, to study the effect on the structural and opto-electronic properties of GaAsBi. The Bi contents of the diodes show both growth temperature and Bi flux dependences. The diodes grown at higher temperatures show evidence of long range inhomogeneity from X-ray diffraction (XRD) measurements, whereas samples of comparable Bi content grown at lower temperatures appear to have well defined, uniform GaAsBi regions. However, the high temperature grown diodes exhibit more intense photoluminescence (PL) and lower dark currents. The results suggest that growth temperature related defects have a greater influence on the dark current than bismuth related defects, and therefore GaAsBi devices should be grown at the highest temperature possible for the desired Bi content.