HVPE GaN wafers with improved crystalline and electrical properties

The quest for low cost GaN substrates with optimized crystalline and electrical properties continues to fuel the search for a fast growth method to produce commercial wafers that will allow the fabrication of devices capable of achieving high performance at high power and/or high frequency. Thick films grown by hydride vapor phase epitaxy (HVPE) on Ammono substrates in addition to reproducing the high crystalline quality of those substrates show significant reduction in free carrier concentration. This work presents a detailed spectroscopic, X-ray diffraction, and Raman spectroscopy imaging investigation of thick freestanding HVPE GaN films deposited on HVPE/Ammono-GaN templates. The results demonstrate that they are stress-free, and have a nearly uniform and relatively lower residual background doping, in addition to high crystalline quality. This result is extremely important, because it demonstrates the usefulness of this new type of HVPE-GaN substrate to fabricate highly efficient optoelectronic and electronic devices. •Silicon and oxygen are the pervasive impurities associated with n-type conductivity.•The concentration of oxygen remains constant across the sample.•Silicon concentration is one order of magnitude larger at Ga-polar face of the crystal.•The high crystalline quality of the Amonothermal substrate is preserved.•Method to produce high crystalline quality substrates with low free carrier concentration.