A series of 100nm thick InGaN films with In contents of up to 14% was grown by MOVPE on SiC substrates. Cathodoluminescence (CL) and remote electron beam induced current (REBIC) in the scanning electron microscope were applied to investigate with high spatial resolution the recombination of carriers at the structural defects present in the films. The observed defects were mainly pinholes formed at the surface. The density of pinholes increases with the In content in the layers, which could be explained by elastic relaxation at pinholes. cathodoluminescence images showed the spatial distribution of the emission sites. For pinholes with diameter in the μm range enhanced luminescence was observed around the pinhole, with a reduced luminescence at the apex. Pinholes were observed in REBIC images as dark spots occasionally surrounded by a bright halo. The halo spreads over an area larger than the pinhole, with a diameter of about 3¯4μm. Also a cell-like dislocation structure was observed in some samples in the cathodoluminescence and REBIC images. cathodoluminescence spectra show, as common features of the samples, a complex emission in the blue range and a broad structured band centered around 670nm. The influence of the inhomogeneous In incorporation on the luminescence of the films and of charged defects on the observed REBIC contrast was explored.

Study of Carrier Recombination at Structural Defects in InGaN Films. A.Cremades, J.Piqueras: Materials Science and Engineering B, 2002, 91-92, 341-4