Growth of GaN single crystal substrates

Self-separating single crystal GaN substrates were grown by hydride-metalor ganic vapor phase epitaxy (H-MOVPE) on closely lattice-matched LiGaO2 subst rates. A critical process for obtaining high quality GaN films on LiGaO2 wa s the initial surface nitridation of the oxide substrate with NH3. This nit riding process and the cooling schedule after growth were critical to achie ving film-substrate self-separation. The as-grown single crystal GaN substr ate exhibited a Bat surface without any mechanical or chemical treatment. N o cracks or residual strain were observed. Different characterization techn iques were used to assess the quality of the substrates and films quality. The surface morphology was examined by AFM and the structural quality was a nalyzed by XRD; the chemical composition was investigated by AES, ESCA, SNM S and SIMS were used to determine composition profiles near the surface. Mi cro Raman spectroscopy was applied for film and substrate characterization. (C) 1999 Elsevier Science S.A. All rights reserved.