Original Paper(Vol.62 No.11 pp.672-678)

Localized States in GaAs1-x Bix and GaAs/GaAs1- x Bix Heterointerface

Takuma FUYUKI, Mizuki ITO, Kousuke KADO and Masahiro YOSHIMOTO

Abstract:The dilute bismuthide III-V semiconductor GaAs1-xBix alloys have unusual properties owing to large bowing of the band gap energy caused by Bi incorporation and a reduction of the temperature coefficients of the band gap. Deep- and shallow-level defects in device-quality GaAs1-x Bix (x 5.4%)are investigated. Deep- and shallow-level defects behave as non-radiative recombination centers and electrical carrier traps. The Bi-related localized states induced by the interaction between spatially localized Bi states and the valence band of GaAs are continuously located up to `90 meV from the valence band with a density of `1~1017cm-3. In spite of concerns about the degradation of the hole mobility in GaAs1-xBix due to scattering at these Bi-related localized states near the valence band, the p-type doping masks the contribution of the Bi-related states to the hole mobility, and a high hole mobility of 200 cm2V-1s-1 is demonstrated. Despite low-temperature growth, the deep-level trap density in GaAs1-x Bix is suppressed on the order of 1015cm-3 comparable to GaAs because of a surfactant-like effect of the Bi atoms. While the interface state density of `8~1011 cm-2eV-1 in a GaAs/GaAs1-xBix heterointerface cannot be reduced by annealing, it can be reduced by half by the insertion of a Bi graded layer into the heterointerface.

Key Words: GaAsBi, Localized states, Interface states, Hole mobility, Photoluminescence, Molecular beam epitaxy