Low-temperature and global epitaxy of GaN on amorphous glass substrates by molecular beam epitaxy via a compound buffer layer

Abstract

GaN epilayers are globally grown on amorphous glass substrates via a compound buffer layer including Ti pre-orienting layer and AlN nucleation layer (NL) grown by molecular beam epitaxy at 530 °C. It is shown that the ratio of V/III during AlN growth plays a key role in the crystallinity of AlN NL as a trade-off between the formation of Al clusters and the mobility of Al adatoms. The N2 flux has an optimal value of 2.4 sccm when the Al flux is fixed to 7.46 × 10−8 Torr at the RF power of 400 W. The obtained smooth GaN epilayer is hexagonal single-crystalline with the grain size in the order of submicron magnitude and root-mean-square roughness of 2.83 nm, which shows the great potential in the epitaxy of III-nitrides on amorphous glass substrates.