MOVPE growth of high quality AlN layers and effects of Si doping

Abstract

High quality AlN layers were grown by MOVPE on c-plane sapphire substrates after optimization of various stages of the epitaxial process. AFM measurements revealed a rms surface roughness of 0.2 nm. The FWHM of HRXRD for the (002) and (114) reflections are 25 and 300 arcsec, respectively. This excellent quality is further confirmed by low temperature (10 K) CL spectra with a FWHM of 10 meV. We observed degrading surface and crystal quality of Si doped samples along with increasing in-plane tensile strain up to a Si concentration of approx. 2·1019 cm-3 and thereafter relaxation for higher concentrations as determined by HRXRD, and low temperature CL measurements. Furthermore, we obtained a weak n-type conductivity, increasing with temperature with an activation energy of about 200 meV. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.