Impact of vicinal GaAs(001) substrates on Bi incorporation and photoluminescence in molecular beam epitaxy-grown GaAs1−xBix

The controlled incorporation of Bi into GaAs is a key challenge to synthesizing dilute Bi materials. This work reveals the importance of the surface step density and direction on Bi incorporation. Steps in the [110] direction are demonstrated to enhance Bi incorporation, but at the cost of reduced photoluminescence intensity at a red-shifted peak position, while steps in the [1¯10] direction yield the opposite behavior. A qualitative model based on the competitive incorporation of As and Bi at different step edges is used to rationalize the observed differences in Bi incorporation.