Papers Published

1. Brown, A.S. and Losurdo, M. and Kim, T.H. and Giangregorio, M.M. and Choi, S. and Morse, M. and Wu, P. and Capezzuto, P. and Bruno, G., The impact of SiC substrate treatment on the heteroepitaxial growth of GaN by plasma assisted MBE, Crystal Research and Technology, vol. 40 no. 10-11 (2005), pp. 997 - 1002 [crat.200410475] .
   (last updated on 2007/04/14)

   Abstract:
   We report on the impact of the preparation of the Si-face 4H-SiC(0001) _Si substrate using a Ga flash-off process on the epitaxial growth of GaN by plasma-assisted molecular beam epitaxy. The nucleation, as well as the resultant structural and morphological properties of GaN grown directly on 4H-SiC(0001)_Si are strongly influenced by the chemical and morphological modifications of the SiC surface induced by the Ga flash-off process. Herein we describe the impact of the specific concentration of Ga incident on the surface (quantified in terms of monolayer (ML) coverage): of 0.5 ML, 1ML and 2ML. The residual oxygen at the SiC surface, unintentional SiC nitridation and the formation of cubic GaN grains during the initial nucleation stage, are all reduced when a 2 ML Ga flash is used. All of the above factors result in structural improvement of the GaN epitaxial layers. The correlation between the SiC surface modification, the initial nucleation stage, and the GaN epitaxial layer structural quality has been articulated using x-ray photoelectron spectroscopy, x-ray diffraction, atomic force microscopy and spectroscopic ellipsometry data. © 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.

   Keywords:
   Epitaxial growth;Semiconducting gallium arsenide;Nitrides;Nucleation;X ray photoelectron spectroscopy;Atomic force microscopy;Spectroscopic analysis;Surface treatment;