Gain spectra and stimulated emission in epitaxial (In,Al) GaN thin films

We measured the emission of (In,Al) GaN films under high intensity optical pumping both in the direction parallel and perpendicular to the film growth. In the edge emission geometry we determine the gain magnitude from the variable stripe length method. We use the spontaneous emission collected perpendicular to the layer plane to calculate the spectral 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 nitride layer plane is predominantly due to scattering of the in-plane stimulated emission. (C) 1996 American Institute of Physics.