Hydrazine cyanurate as a nitrogen source for thin nitride film growth

Abstract

The use of liquid hydrazine (N2H4) as a nitrogen source for nitridation reactions has been restricted because of safety, purity, and difficulties in using a liquid source. Hydrazine cyanurate (HC) is a stable solid complex of N2H4 which can be easily handled and purified before use and which evolves pure N2H4 upon heating, thus making it a promising source of N2H4 for nitridation reactions. In this article, a process for the synthesis of HC has been developed which decreases the H2O content of the evolved N2H4 from 10% when H2O was used as the solvent in the synthesis of HC to 0.7% by replacing H2O with dimethylsulfoxide as the solvent in the synthesis of HC. The use of the purified HC is demonstrated as a solid source in the nitridation of (100) GaAs substrates at 200 °C in a low pressure chemical vapor deposition reactor. The nitridated GaAs surfaces were analyzed by x-ray photoelectron spectroscopy and were found to be primarily comprised of GaN, GaAs, and Ga2O3. The ratio of the constituent peak heights in the Ga 3d peak of GaN to Ga2O3 was 2.25 in the grown nitride films. The oxide impurities were most likely due to incomplete removal of the native substrate oxide formed prior to growth and were not a product of the nitridation.