PHOTON RECYCLING AS THE DOMINANT PROCESS OF LUMINESCENCE GENERATION IN AN ELECTRON-BEAM EXCITED N-INP EPILAYER GROWN ON AN N(-INP SUBSTRATE())

We examine the room-temperature dispersive and non-dispersive cathodol uminescent (CL) signals produced by an n-InP/n(+)-InP homojunction as a function of excitation beam energy. The non-intentionally doped epil ayer of the homojunction is thick enough (2.5 mu m) that it can be inv estigated independently of the substrate by choosing beam energies low er than 25 keV. The red-shift of CL peak, as well as the drastic chang e of the shape of the CL spectra, observed when increasing the beam en ergy, are explained in terms of photon recycling. The luminescence of the epilayer is found to be governed by the recycling of photons origi nating from the substrate. This leads to an increase of the external l uminescence efficiency of the epilayer compared with that expected in homojunctions with undoped substrates. We also present a determination of the diffusion-recombination parameters of the structure.