SEARCH

SEARCH BY CITATION

Keywords:

  • AlInN-based heterojunctions;
  • TEM;
  • electron holography;
  • field-effect transistors

Abstract

The microstructure, composition and electrostatic fields of near-lattice-matched Al1-xInxN/AlN/GaN heterostructures and devices have been characterized using a variety of electron microscopy techniques. A thin parastic Ga-rich layer was often observed immediately above the AlN spacer and was attributed to GaN nucleation during specimen cooling. Mapping of electrostatic potential profiles across a GaN/Al0.85In0.15N/AlN/ GaN heterostructure using off-axis electron holography showed polarization-induced fields of 7.5MV/cm within the AlN layer, and 2.2MV/cm within the Ga-rich layer. A two-dimensional electron gas with a density of ∼9.8×1012 cm–2 was observed in the underlying GaN layer located very close to the AlN/GaN interface. Contact inclusions were observed extending into the AlInN and GaN layers along mixed-type threading dislocations under the source and drain regions of HFET devices. The density and size of the contact inclusions was determined by the annealing temperature (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)