A Comparative Photoelectron Spectroscopic Analysis of MBE and MOCVD Grown Epitaxial GaN Films

摘要: The report presents X-Ray Photoelectron Spectroscopic analysis of as-received and cleaned MBE MOCVD grown undoped epitaxial GaN films. We correlate observed changes in electronic structure surface properties after employing a newly derived approach to clean surfaces. adopted is combination two different standard cleaning procedures consisting ex-situ wet chemical (HCl) etching followed by an in-situ ultrahigh vacuum anneal (up 750 °C), successfully yielded stoichiometric surface. method was employed investigate cleanliness films it that major contaminants such as carbon oxygen were significantly removed from the XPS revealed show higher amount contamination than but can also be more efficiently. Thermal annealing (≥ °C) resulted dissociation bonds accumulation metallic gallium on films, which confirmed core level well valence band spectra. n O/n N ratio reduced drastically 1.79 0.04 0.73 0.09 with stoichiometry (N:Ga) 1.0 ± 1.1 0.05 for respectively. VB maximum position shifted 2.9 0 eV 2.2 0.1 2.8 1.4