Effect of Bi Alloying on the Hole Transport in the Dilute Bismide Alloy GaAs1-xBix

We studied the effect of Bi incorporation on the hole mobility in the dilute bismide alloy GaAs_1-xBi_x using electrical transport (Hall) and photoluminescence (PL) techniques. Our measurements show that the hole mobility decreases with increasing Bi concentration. Analysis of the temperature-dependent Hall transport data of p-type GaAsBi epilayers along with low-temperature PL measurements of p-doped and undoped epilayers suggests that Bi incorporation results in the formation of several trap levels above the valence band, which we attribute to Bi-Bi pair states. The decrease in hole mobility with increasing Bi concentration can be explained as being caused by scattering at the isolated Bi and the Bi-Bi pair states. We also observed a decrease in hole concentration with Bi incorporation. We believe that Bi _Ga heteroantisite defects compensate the acceptors, thus reducing the effective hole concentration.