Band-to-band recombination in N+ InP substrate: Evidence of photon recycling

Quantitative nondispersive cathodoluminescence (CL) measurements and dispersive CL experiments are performed at room temperature on n(+)-InP substrates as a function of the accelerating voltage (Eo). The results are explained in terms of band-to-band recombination. The red shift of the CL spectrum observed when increasing Eo, as well as the large value of the measured diffusion length with respect to the radiative one are interpreted on the basis of a high efficiency of the photon recycling process.