Cathodoluminescence study of domains, defects, and interdiffusion in ZnSe/GaAs(100)

The distribution of dislocations and domains found in thin ZnSe films grown by molecular-beam epitaxy on GaAs(100) has been examined with low-temperature cathodoluminescence (CL) imaging and spectroscopy. Dark-line and bright-line defects in the low-temperature CL imaging of the free-exciton (FE) and Y-band emissions, respectively, are found to correlate with the presence of [11̄0]-oriented misfit dislocations for 1-μm-thick films found to grow nearly two dimensionally. For a sample exhibiting mixed two- and three-dimensional growth characters, large domains (∼1-5 μm widths) in the CL imaging of the ZnSe FE emission were found to correlate with a cellular pattern found in the imaging of the GaAs exciton and band-edge-to-acceptor emissions. These results show that the optical properties of the ZnSe film and GaAs substrate are coupled and influenced by Zn diffusion into the substrate during growth.