Evidence of localized boron impurity states in (B,Ga,In)As in magnetotransport experiments under hydrostatic pressure

Abstract

We investigate the magnetotransport properties of n-type (B,Ga,In)As alloys and an n-type GaAs reference sample under hydrostatic pressure up to 16 kbar in the temperature range from 1.6 to 300 K. The free carrier concentration and the mobility of the reference sample are almost independent of the applied hydrostatic pressure. In contrast, the free carrier concentration and the mobility in ${\mathrm{B}}_{0.027}$${\mathrm{Ga}}_{0.913}$${\mathrm{In}}_{0.06}$As alloys drop by orders of magnitude over the accessible pressure range. The observations can be explained by assuming that a boron-related density of localized states exists in the vicinity of the conduction band edge of the alloy. The analysis of the pressure-induced changes of the free carrier concentration yields an image of the boron-related density of localized states with characteristic features that are found to be in good agreement with theoretical calculations using a linear combination of isolated states model. Our results provide strong evidence that boron-related states act as isovalent traps in (B,Ga,In)As alloys.