Effect of boron localized states on the conduction band transport in B_xGa_1−xP

We study the magnetotransport properties of an n-type (B,Ga)P:Te alloy and an n-type GaP:Te reference under hydrostatic pressure up to 17 kilobars in the temperature range from 1.5 to 300 K. The free carrier concentration and the mobility of the reference sample are almost independent of the applied hydrostatic pressure at room temperature. In contrast, the free carrier concentration as well as the mobility in the B_0.012Ga_0.988P:Te alloy increase by about 30% over the accessible pressure range. The observations are explained by assuming that a boron-related density of localized states exists in the vicinity of the conduction band edge of the alloy. These boron states act as electron traps as well as efficient scatter centers. Applying hydrostatic pressure shifts the energetic positions of conduction band edge at the X-point (where the electron transport takes place) and of the boron states apart reducing the impact of boron on the electronic transport properties of the alloy.