Ammonia Impurities Critical To The Performance Of Nitride Semiconductor Devices

Abstract

AlGaN/GaN HEMT devices were grown under specific experimental conditions designed to elucidate the effects of purification of the ammonia gas. Two different, commercially available, purifiers were tested under identical growth conditions along with three different grades of ammonia. After growth of the AlGaN/GaN layers, the wafers were subjected to Hall measurements where the sheet concentration, and mobility, were determined. The results clearly showed significantly enhanced performance for the inorganic based purifier compared to the resin based organometallic purifier for all experimental parameters tested. Additionally, the nitride devices were subjected to SIMS analysis with depth profiling in an attempt to identify the elemental nature of the impurities that caused the discrepancy in performance results between the various samples. Results from the Hall measurements and the SIMS analysis are presented and correlated to the conditions controlled during the growth of the nitride devices.