SURFACE CHEMICAL STATES OF HETEROEPITAXIAL NITRIDE FILMS ON SAPPHIRE BY METALORGANIC CHEMICAL VAPOR DEPOSITION

Surface chemical states of GaN , AlGaN and InGaN by metalorganic chemical vapor deposition, and the influence of different dopants are studied with X-ray Photoelectron Spectroscopy (XPS). The results show that for most of the samples the N 1s peak can be fitted with a dominant GaN peak and a small N – H peak, while Ga 3d can be deconvoluted into three peaks from elemental Ga , GaN and Ga 2 O 3. Si -doping appears to have small influence on the surface chemical states of GaN while the influence of Mg -doping appears larger. In addition to a change in the component intensities, Mg -doping also causes the N 1s and Ga 3d peaks to broaden. The ternary AlGaN sample shows aluminum surface segregation, while the undoped InGaN shows indium surface deficiency.