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 plasma-assisted molecular beam epitaxy. High resolution x-ray diffraction and scanning electron microscope studies indicate that the mosaic disorder decreases with increasing film thickness and increasing growth temperature. The grain size increases with the growth temperature. The best (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 with a Langmuir probe near the growth position and analyzed to extract the nitrogen ion density and energy for the growth conditions used.