Deep levels near ‘‘buried’’ ZnSe/GaAs(100) heterointerfaces

We have used low energy cathodoluminescence spectroscopy (CLS) and laser photoluminescence spectroscopy (PLS) to identify the energies and depth variation of deep levels near the buried, molecular beam epitaxy‐grown ZnSe/GaAs(100) heterointerface. Using a combination of electron excitation energies and laser wavelengths to obtain CLS/PLS ‘‘depth profiles’’ through the interface regions of 150–500‐nm‐thick ZnSe epilayer/GaAs substrate structures, we find that deep electronic states are formed near the heterojunction and within the epilayer whose relative emission intensities vary dramatically with beam pressure ratio. For Zn (Se)‐rich interface, features at 0.9, 1.0, and 1.14 eV (1.3 eV) are dominant. An additional feature at 1.9 eV appears with high temperature annealing. In general, intensities of the 1.3 and 1.9 eV features appear most intense for excitation depths corresponding to the buried interface regions. These spectral features demonstrate substantial differences in the localized interface states formed under variant epilayer growth conditions. They also provide an effective in situ monitor of heterointerface quality and stability.