A GaN SiC hybrid material for high frequency and power electronics
We demonstrate that 3.5% in plane lattice mismatch between GaN (0001) epitaxial layers and SiC (0001) substrates can be accommodated without triggering extended defects over large areas using a grain boundary free AlN nucleation layer (NL) Defect formation in the initial epitaxial growth phase is thus significantly alleviated, confirmed by various characterization techniques. As a result, a high quality 0.2 mm thin GaN layer can be grown on the AlN NL and directly serve as a channel layer in power devices, like high electron mobility transistors (HEMTs) The channel electrons exhibit a state of the art mobility of >2000 cm2/V s, in the AlGaN/GaN heterostructures without a conventional thick C or Fe doped buffer layer. The highly scaled transistor processed on the heterostructure with a nearly perfect GaN SiC interface shows excellent DC and microwave performances. A peak RF power density of 5.8 W/mm was obtained at VDSQ 40 V and a fundamental frequency of 30 GHz. Moreover, an unpassivated 0.2 mm GaN/AlN/SiC stack shows lateral and vertical breakdowns at 1.5 kV. Perfecting the GaN SiC interface enables a GaN SiC hybrid material that combines the high electron velocity thin GaN with the high breakdown bulk SiC, which promises further advances in a wide spectrum of high frequency and power electronics.We demonstrate that 3.5% in plane lattice mismatch between GaN (0001) epitaxial layers and SiC (0001) substrates can be accommodated without triggering extended defects over large areas using a grain boundary free AlN nucleation layer (NL) Defect formation in the initial epitaxial growth phase is thus significantly alleviated, confirmed by various characterization techniques. As a result, a high quality 0.2 mm thin GaN layer can be grown on the AlN NL and directly serve as a channel layer in power devices, like high electron mobility transistors (HEMTs) The channel electrons exhibit a state of the art mobility of >2000 cm2/V s, in the AlGaN/GaN heterostructures without a conventional thick C or Fe doped buffer layer. The highly scaled transistor processed on the heterostructure with a nearly perfect GaN SiC interface shows excellent DC and microwave performances. A peak RF power density of 5.8 W/mm was obtained at VDSQ 40 V and a fundamental frequency of 30 GHz. Moreover, an unpassivated 0.2 mm GaN/A.