Effects of implantant depth distribution on photoluminescence spectra in Be-implanted GaAs

Photoluminescence spectra from ion-implanted Be acceptors in GaAs have been studied as a function of wavelength and intensity of excitation light over the implant-fluence range 3 x 1012 to 1 x 1015 cm-2. It is demonstrated that the nonuniform distributions of implantant concentration as a function of depth in the implanted layer produce a profiling effect which causes anomalous changes in photoluminescence line shapes and energy positions as a function of excitation intensity. These results imply photoexcited carrier diffusion lengths of much less than 1 μm in implanted and annealed layers in bulk GaAs