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Keywords:

  • InAlN/GaN HEMTs;
  • thin GaN buffer;
  • mesa technology;
  • on-off ratio;
  • buffer scaling

Abstract

This contribution reports on a GaN on sapphire mesa technology for lattice matched InAlN/GaN HEMTs similar to a silicon on insulator technology. Ultrathin buffer layers between 500 nm and 100 nm have been deep mesa etched down to the substrate to avoid cross talk between devices through the buffer and provide full transparency outside the active device area (of special interest to biochemical sensor applications).The heterostructure characteristics were: NS > 1.6 x 1013 cm-2, Rsh < 600 Ω/□. 0.25 µm gate length HEMT device characteristics are moderate, but essentially similar down to 200 nm buffer thickness. Devices on 100 nm buffer layer are still difficult to reproduce. Ion/Ioff was up to 109 and sub-threshold slopes down to 90 mV/dec (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)