Low radio frequency loss and buffer-free GaN directly on physical-vapor-deposition AlN/Si templates

Abstract

We demonstrate 1.5 μm thick buffer-free GaN layers directly on physical vapor deposited (PVD) AlN/Si templates via delayed coalescence growth. The full width of half maximum of the X-ray diffraction rocking curves for GaN (002)/(102) planes are 525/527 arcsec. The PVD-AlN with low density and large size AlN nuclei, combined with 3D growth mode of the GaN, contribute to the delayed coalescence growth and thus crack-free GaN layers. The PVD-AlN can also effectively suppress the Ga/Al diffusion and lead to a low radio frequency loss of 0.20 dB mm−1 at 10 GHz for the GaN layers.