Polycrystalline layers were grown by ECR molecular beam epitaxy onto quartz glass substrates. A strong photoluminescence emission was observed. The analysis of these layers was carried out by using high-resolution transmission electron microscopy. It was shown that the microstructure was characterized by columnar growth, with the <00•1> direction parallel to the growth direction. The mean size of the grains was in the range of 30 to 50nm. Sphalerite cubic and wurtzite hexagonal phases were observed, and some defects such as basal stacking faults were present. Inversion domain boundaries were also formed. However, no threading dislocations within the grains were visible.

Polycrystalline GaN - Analysis of the Defects. G.Nouet, P.Ruterana, H.Tampo, H.Asahi: Physica Status Solidi C, 2003, 0[1], 409-12