MICROSTRUCTURE AND PHOTOLUMINESCENCE OF GAN GROWN ON SI(111) BY PLASMA-ASSISTED MOLECULAR-BEAM EPITAXY

Wurtzite GaN films on AlN buffer layers were grown on Si(111) by plasm a-assisted molecular beam epitaxy. High resolution x-ray diffraction a nd scanning electron microscope studies indicate that the mosaic disor der decreases with increasing film thickness and increasing growth tem perature. The grain size increases with the growth temperature. The be st (0002) diffraction peak full width at half-maximum is 22 arcmin for a film 1.7 mum thick. Prominent low-temperature exciton luminescence is observed at 3.46 eV. The plasma I-V characteristics are measured wi th a Langmuir probe near the growth position and analyzed to extract t he nitrogen ion density and energy for the growth conditions used.