Promising characteristics of GaN layers grown on amorphous silica substrates by gas-source MBE

Polycrystalline GaN layers are grown on amorphous fused silica glass substrates by gas-source MBE using ion removed electron cyclotron resonance (ECR) radical cell. Polycrystalline GaN grown here shows a strong photoluminescence without deep-level emission. The emission peak with a wide spectral half-width is red-shifted from the excitonic emission of a GaN layer grown on a sapphire substrate. The peak is excitonic from the excitation power and temperature dependencies of the PL spectrum. Photoluminescence excitation spectra show that the polycrystalline GaN has a large Stokes shift. The results suggest that the polycrystalline GaN has a large potential fluctuation due to a grain to grain potential distribution and that the strong emission originates from the lower-energy tail of the absorption spectrum, Such optical properties indicate that the polycrystalline GaN layers grown on the glass substrates are promising to fabricate large area and low cast light-emitting devices and solar cells. Polycrystalline optical device technology will be indispensable for industrial applications as well as the polycrystalline and the amorphous Si devices. (C) 1998 Elsevier Science B.V, All rights reserved.