Deep level formation and heterojunction band offsets at ZnSe/GaAs interfaces

We have used photoluminescence (PLS) to measure charge injection across the ZnSe/GaAs interface and subsequent near-band-edge (NBE) and deep level recombination as a function of interdiffusion and deep level formation. We have performed these studies for a set of heterojunction growth parameters corresponding to a range of band offsets. Our earlier results provided evidence for growth-dependent deep level emission at the ZnSe/GaAs(100) heterointerface, new deep level formation at elevated temperatures associated with atomic interdiffusion across the junctions, and major changes in recombination with the onset of defect formation. Here we present simultaneous GaAs and ZnSe PLS measurements demonstrating the first order effect of deep level formation on the internal photoemission of free carriers across the heterojunction and the dramatic difference in NBE recombination with defect formation for different stoichiometries of ZnSe growth. These features underscore the systematic role of deep levels in altering heterojunction dipoles and band offset barriers to charge injection.