Interface properties of an AIN/(AIN) x(SiC) 1-x/4H-SiC heterostructure

J. H. Edgar, Z. Gu, L. Gu, David Smith

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Abstract

The crystal structure and compositional changes near the two interfaces of a AlN/(AlN) x(SiC) 1-x/4H-SiC heterostructure prepared by sublimation-recondensation growth were examined by cross-sectional transmission electron microscopy. Deposition of an (AlN) x(SiC) 1-xlayer between a SiC seed and a bulk AlN crystal is potentially beneficial for gradually changing the lattice constants and coefficient of thermal expansion from SiC to AlN. A compositional transition layer adjacent to the 4H-SiC substrate suggested interdiffusion between the substrate and the alloy layer. The alloy had the 4H-polytype crystal structure in this layer; above the layer, the alloy exhibited the typical 2H-polytype. Voids were present at the AlN/(AlN) xSiC) 1-x interface, due to the decomposition of the (AlN) xSiC) 1-x layer before the A1N layer had completely coalesced. The nominally pure A1N layer contained approximately 8% of Si and C, possibly coming from the decomposition of the alloy layer and/or the substrate during growth of the AlN layer. Both interfaces were abrupt, to less than 50 nm, with low densities of threading dislocations. Dislocations in both the (AlN) x(SiC) 1-x and AlN layers were not threading, but ran parallel to the (0001) planes.

Original languageEnglish (US)
Pages (from-to)3720-3725
Number of pages6
JournalPhysica Status Solidi (A) Applications and Materials Science
Volume203
Issue number15
DOIs
StatePublished - Dec 1 2006

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering
  • Materials Chemistry

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