Electrical and recombination properties and deep traps spectra in MOCVD ELOG GaN layers

Electrical properties, deep levels spectra, spectra of microcathodoluminescence, diffusion lengths of minority carriers were studied in undoped GaN films grown by standard metallorganic chemical vapour deposition on sapphire and by the epitaxial lateral overgrowth technique (ELOG). It is shown that the total concentrations of shallow donors and of electron and hole traps are very considerably lower in the ELOG material compared to the ordinary MOCVD samples. MCL and electron beam induced current EBIC imaging of ELOG samples suggests that the dislocation density in the overgrown regions is on the order of 106 cm^-2 while in-between these regions it is similar to the dislocation density in the standard material, about 109 cm^-2. Local diffusion lengths were shown to follow the same trend as dislocation densities.