Surface and Bulk Electronic Structure of Thin Film Wurtzite GaN and Related Wide Band Gap Nitride Semiconductors

-Kevin Smith, Boston University

III-V nitride wide band gap semiconductors are important electronic materials due to potential applications in high temperature electronic devices and in blue wavelength light emitting diodes and lasers. Despite recent success in the growth of high quality films of these nitrides, many problems remain. Among the outstanding issues are the intentional doping of the films, the nature of defects in the films, and the formation of stable interfaces. All of these problems are related directly to the fundamental electronic structure of the nitrides. I will present the results of a study of the bulk and surface electronic structure of n-type GaN thin films. We have used high resolution x-ray emission spectroscopy to study the bulk partial density of states, and angle resolved photoemission (ARP) to study the band dispersion of the valence states. The results of these measurements will be compared to theory. We have also observed an occupied surface state on GaN using ARP, and will report on the properties of this state. Preliminary data concerning x-ray emission studies of the valence band structure of AlGaN and InGaN alloys will also be presented.

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