DX CENTERS IN II-VI SEMICONDUCTORS AND HETEROJUNCTIONS

Measurements of the photoconductivity and Hall effect in Ga-doped ZnSe indicate that Ga donors form DX states in ZnSe. When the photocarrier s remain in the ZnSe:Ga layer, the photoconductivity is persistent up to T-a = 100K, due to a barrier to recapture the photocarriers, E(c) a pproximate to 0.3eV. Under certain growth conditions, there is a large conduction band offset at the heterojunction with the GaAs substrate. The photocarriers are trapped at the interface, causing an enhancemen t of the annealing temperature to T-a approximate to 350K. We discuss the implications of these results to device applications.