A-plane GaN films are deposited on （302） γ-LiAlO2 substrates by metalorganic chemical vapor deposition （MOCVD）. The X-ray diffraction （XRD） results indicate that the in-plane orientation relationship between GaN and LAO substrates is [010]LAO//[0001]CaN and [203]LAO//[1100]GaN with 0.03% and 2.85% lattice mismatch, respectively. Raman scattering results indicate that the strain in the films decreases along with the increase in the thickness of the films. In addition to the band edge emission at 3.42 eV, defects-related luminescence at 3.35 eV is observed in the photoluminescence （PL） spectra. The cathodoluminescence （CL） spectra indicate that the 3.35-eV emission is related to the V pits.
γ-LiAlO2 single crystal is a promising substrate for GaN heteroepitaxy. In this paper, we present the growth of large-sized LiAlO2 crystal by modified Czochralski method. The crystal quality was characterized by high-resolution X-ray diffraction and chemical etching. The results show that the as-grown crystal has perfect quality with the full width at half maximum （FWHM） of 17.7-22.6 arcsec and etch pits density of （0.3- 2.2）×10^4 cm^-2 throughout the crystal boule. The bottom of the crystal boule shows the best quality. The optical transmission spectra from UV to IR exhibits that the crystal is transparent from 0.2 to 5.5μm and becomes completely absorbing around 6.7μm wavelength, The optical absorption edge in near UV region is about 191 nm.
Taohua HUANGShengming ZHOUHao TENGHui LINJun ZOUJianhua ZHOUJun WANG
