High-temperature AlN templates were grown onto sapphire substrates by using metalorganic chemical vapour deposition. AFM results showed that the root-mean-square surface roughness was only 0.11nm. Optical transmission spectra and high-resolution X-ray diffraction confirmed the high quality of the AlN template. The X-ray diffraction (002) rocking curve full-width at half-maximum was about 53.7arcsec and the (102) full-width at half-maximum was about 625arcsec. The densities of screw and edge threading dislocations were estimated to be ~6 x 106 and ~4.7 x 109/cm2, respectively. AlGaN, with an Al content of 80.2% was also grown onto the AlN template. The root-mean-square of the surface roughness was about 0.51nm. X-ray diffraction reciprocal space-mapping was used to determine accurately the Al composition and relaxation status of the AlGaN epilayer. The X-ray diffraction (002) rocking curve full-width at half-maximum of the AlGaN epilayer was about 140arcsec and the (102) full-width at half-maximum was about 537arcsec.

High Quality AlGaN Grown on a High Temperature AIN Template by MOCVD. J.Yan, J.Wang, N.Liu, Z.Liu, R.Jun, J.Li: Journal of Semiconductors, 2009, 30[10], 103001