Post growth rapid thermal annealing of GaN: The relationship between annealing temperature, GaN crystal quality, and contact-GaN interfacial structure

Microstructure of GaN films grown by metalorganic chemical-vapor-deposition (MOCVD) on c-sapphire substrates has been accessed as a function of post-growth rapid thermal annealing (RTA) temperatures from 600 degrees C to 800 degrees C. The influence of the thermally modified, new-surface crystalline quality on sputtered WSI contact to GaN was also evaluated, Similar planar defects were observed in all heat treated samples: only their density differed, Our analyses demonstrated a strong relationship between the improved GaN crystal quality and postgrowth high-temperature thermal processing. The density of the near-surface defects was lowered by 61% as the annealing temperature was raised from 600 degrees C to 800 degrees C, Depression of the near-surface defects encouraged development of the beta-W2N interfacial phase and promoted metal-semiconductor interface smoothness. (C) 1997 American Institute of Physics.