Hexagonal GaN films deposited by reactive hot wall evaporation technique

Gallium nitride (GaN) films were deposited by reactive hot wall evaporation technique onto fused silica (quartz) substrates at different substrate temperatures (573-773 K). The films were characterized by measuring microstructural, optical and electrical properties. The GaN films were predominantly hexagonal. The band gap (similar to 3.4 eV) refractive index (1.42-2.52) and surface roughness (10-46 nm) could be evaluated from the optical absorption spectra. The variation of AC conductivity sigma(omega) with frequency (omega) at different temperatures (134-300 K) indicated a dependence sigma(omega) =Aomega(s) with s varying within 0.85-0.97 having a weak temperature dependence. Elliot's model was utilized to interpret the conductivity data of GaN, which indicated the density of localized states to be similar to 4.5 X 10(18)cm(-3). (C) 2002 Elsevier Science B.V. All rights reserved.