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Title: Surface oxidation of GaN(0001): Nitrogen plasma-assisted cleaning for ultrahigh vacuum applications

The cleaning of metal-organic vapor-phase epitaxial GaN(0001) template layers grown on sapphire has been investigated. Different procedures, performed under ultrahigh vacuum conditions, including degassing and exposure to active nitrogen from a radio frequency nitrogen plasma source have been compared. For this purpose, x-ray photoelectron spectroscopy, reflection high-energy electron diffraction, and scanning tunneling microscopy have been employed in order to assess chemical as well as structural and morphological surface properties. Initial degassing at 600 °C under ultrahigh vacuum conditions only partially eliminates the surface contaminants. In contrast to plasma assisted nitrogen cleaning at temperatures as low as 300 °C, active-nitrogen exposure at temperatures as high as 700 °C removes the majority of oxide species from the surface. However, extended high-temperature active-nitrogen cleaning leads to severe surface roughening. Optimum results regarding both the removal of surface oxides as well as the surface structural and morphological quality have been achieved for a combination of initial low-temperature plasma-assisted cleaning, followed by a rapid nitrogen plasma-assisted cleaning at high temperature.
Authors:
 [1] ; ; ; ; ;  [2]
  1. Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany and Department of Physics, Birla Institute of Technology and Science, Pilani, 333031 Rajasthan (India)
  2. Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen (Germany)
Publication Date:
OSTI Identifier:
22318058
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films; Journal Volume: 32; Journal Issue: 5; Other Information: (c) 2014 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; DEGASSING; ELECTRON DIFFRACTION; GALLIUM NITRIDES; NITROGEN; ORGANOMETALLIC COMPOUNDS; OXIDATION; OXIDES; PLASMA; PRESSURE RANGE BELOW 1 NANO PA; PRESSURE RANGE MICRO PA; PRESSURE RANGE NANO PA; SAPPHIRE; SURFACE CLEANING; X-RAY PHOTOELECTRON SPECTROSCOPY