GaAs1-xBixおよびGaAs/GaAs1-xBixヘテロ界面における局在準位

概要

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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-xBix (χ ≤ 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 ∼90meV 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-xBix 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 × 1011cm-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.
公益社団法人日本材料学会の論文