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Keywords:

  • GaN;
  • AlGaN;
  • sheet electron density;
  • mobility

Abstract

Temperature dependence of sheet electron density (ns) and mobility (µ) of the two dimensional electron gas has been investigated in AlGaN/GaN hetero- structures deposited with different metal stacks such as Ti/Al, Ti/Au, V/Au, and Ni/Au. It was found that a sudden increase in nsand a hump in µ were observed with the temperature increase corresponding to the onset of reaction between the bottom metal (Ti, V, or Ni) and the AlGaN layer. At room temperature, Ti/Al showed an order of magnitude higher ns and 50% higher µ by annealing, while the amount of increase was much less for other metal stacks, indicating that Al played a key role for the increase in ns and µ. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)