Magnetron Sputter Epitaxy of GaN

Abstract: Electronic-grade GaN (0001) epilayers have been grown directly on Al2O3 (0001) substrates by reactive DC-magnetron sputter epitaxy (MSE) from a liquid Ga sputtering target in an Ar/N2 atmosphere. The as-grown GaN epitaxial film exhibit low threading dislocation density on the order of ≤ 1010 cm-2 obtained by transmission electron microscopy and modified Williamson-Hall plot. X-ray rocking curve shows narrow fullwidth at half maximum (FWHM) of 1054 arcsec of the 0002 reflection. A sharp 4 K photoluminescence peak at 3.474 eV with a FWHM of 6.3 meV is attributed to intrinsic GaN band edge emission. The high structural and optical qualities indicate that MSEgrown GaN epilayers can be used for fabricating high-performance devices without the need of any buffer layer. GaN (0001) thin films were grown on Al2O3 substrates by reactive high power impulse magnetron sputtering of liquid Ga targets in a mixed N2/Ar discharge. A combination of x-ray diffraction, electron microscopy, atomic force microscopy, μ-Raman microscopy, photoluminescence, time of flight elastic recoil detection, and cathodoluminescence showed the formation of both relaxed and strained domains in the same films. . While the strained domains form due to ion bombardment during growth. The relaxed domains exhibit superior structural and optical properties comparative to the strained domains, including room temperature luminescence.