Producibility of Gallium Nitride Semiconductor Materials

The overall objective of this program is to improve the producibility of HVPE GaN through the use of in-situ monitoring during the growth process. Various in-situ monitoring devices will be used: a UV absorption technique to monitor the GaCl concentration above the growing GaN wafer; a commercial BandiT system capable of measuring optical emission from the growing wafer in order to measure the substrate temperature; a commericial MOSS system to measure wafer bow during growth; an acoustic emission monitor to understand wafer cracking; and a differentially pumped mass spectrometer to measure the concentrations of various species in the exhaust of the reactor. In conjunction with thermal, gas flow, and chemical reaction simulation, these in-situ monitoring devices will allow for better control of key growth variables, which in turn will lead to the development of a robust, producible growth processes. The aim of these in-situ monitor defined growth processes is to give maximum process latitude in the development of optimized and reproducible growth parameters, specifically tuned to improve yield in large area wafers and thicker boules, whose quality will be verified by demonstrating high quality homoepitaxy, as evidenced by high mobility and high sheet density 2DEGs with the University partner.