Investigation on growth modes of GaN layers grown by LIRE

GaN layers are usually grown by metalorganic chemical vapour deposition (MOCVD), MBE and related processes. In this work we compare the growth of GaN layers by laser induced reactive epitaxy (LIRE) with the growth by conventional methods with special interest in growth modes of the different processes. The influence of deposition parameters as temperature and Ga/N-ratio, for LIRE represented in the energy of the laser beam, is discussed. MOCVD produces smooth films with growth steps on the surface, indication of one-dimensional growth. MBE films usually exhibit island-like growth, changing with Ga/N ratio from a meander structure over a closed surface with pits to a surface with etching-features due to desorption. The best luminescence intensities are achieved with surfaces of meander structure and with surfaces showing slight etching features. LIRE layers are found to be similar to MBE layers in surface structure and in the influence of the Ga/N-ratio.