Insulating GaN Substrates for High Performance AlGaN/GaN HEMTs

AlGaN/GaN HEMTs offer excellent dc and rf device performance over a broad range of contact dimensions. Future refinements should focus on reducing defect density in the epi layers that can lead to current collapse and thereby provide more stable operationover commercially significant periods. There is an urgent need for insulating, lattice-matched substrates with good thermal conductivity. UF has recently demonstrated the use of MgO and Sc2O3 surface passivation films for reducing the effect of surfacestates on the dc and rf performance of AlGaN/GaN HEMTs. The major remaining hurdle to commercialization of HEMTs is the availability of insulating, lattice-matched substrates. TDI, Inc will focus on developing insulating bulk GaN, while UF will perform theepi-growth and device fabrication and testing. Insulating bulk GaN substrates developed by TDI, Inc will be used for growth and processing of high performance HEMT device structures. Homo-epitaxy will allow a reduction in defect density and theinsulating nature of the substrate will avoid reducing the rf performance of the HEMT through additional capacitance.