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Keywords:

  • 43.35.Pt;
  • 62.65.+k;
  • 68.60.–p;
  • 77.65.Dq;
  • 81.05.Ea;
  • 85.50.–n

Abstract

A review of the fabrication techniques of surface acoustic wave (SAW) devices in nitrides, and their most relevant device properties, is presented. Several acoustic modes are observed in the transfer functions of the filters: besides the Rayleigh wave, guided modes (Sezawa) arise when the sound velocity in the nitride layer is lower than in the substrate, and pseudobulk modes may also appear. The effect of the substrate characteristics will be addressed, including the anisotropy found in nitride devices grown on sapphire due to the crystal structure mismatch. Regarding applications, some results in the sensor and photonics fields are summarized. Finally, two novel devices will be discussed: a SAW-assisted photodetector, based on the integration of a SAW generator and a UV photodetector, and a DC controlled SAW filter, obtained by the fabrication of a SAW device on a 2DEG AlGaN/GaN heterostructure. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)