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Keywords:

  • AlGaN/GaN heterostructures;
  • surface passivation;
  • PH3;
  • HfO2

Abstract

Different surface passivation methods of AlGaN/GaN heterostructures were investigated in this work. C-V measurement shows that very high trap density (Dit) of 1.51×1013cm-2eV-1 exists at the AlGaN/GaN surface, which has activation energy of 0.765 eV. The surface treatment by using O2 plasma treatment and HfO2 dielectric can efficiently lower Dit to 3.57×1012cm-2eV-1 and 1.06×1012cm-2eV-1, repectively. To reduce these deep trap states further, a more effective passivation method is presented here. By using the PH3 plasma treatment before the HfO2 deposition, Dit was further greatly reduced and reached a very low value of 1.37×1011cm-2eV-1. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)