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 language | English (US) |
---|---|
Pages (from-to) | 3720-3725 |
Number of pages | 6 |
Journal | Physica Status Solidi (A) Applications and Materials Science |
Volume | 203 |
Issue number | 15 |
DOIs | |
State | Published - Dec 2006 |
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