BROAD EMISSION BAND IN GAN EPITAXIAL LAYERS GROWN ON 6H-SIC AND SAPPHIRE

Mid-band-gap emissions in GaN epilayers grown on 6H-SiC and sapphire a re studied by time-resolved spectroscopy (TRS). The yellow luminescenc e peaking at ca. 1.2 eV at low-temperature shifts to higher energies w ith increasing temperature. The presence of emission with the same cha racteristics in samples grown on different substrates and by different processes indicates that the defects responsible for the emission are of intrinsic nature but dependent on the cubic or hexagonal habit of the crystals. TRS are compared with cathodoluminescence (CL) in a scan ning electron microscope (SEM) and optically detected magnetic resonan ce (ODMR) data.