GAIN SPECTRA AND STIMULATED-EMISSION IN EPITAXIAL (IN,AL) GAN THIN-FILMS

We measured the emission of (In,Al) GaN films under high intensity opt ical pumping both in the direction parallel and perpendicular to the f ilm growth. In the edge emission geometry we determine the gain magnit ude from the variable stripe length method. We use the spontaneous emi ssion collected perpendicular to the layer plane to calculate the spec tral dependence of the gain. Finally, we compare the emission spectra with those obtained for high quality GaAs thin films and find that the observation of a stimulated emission peak perpendicular to the nitrid e layer plane is predominantly due to scattering of the in-plane stimu lated emission. (C) 1996 American Institute of Physics.