13 January 2011

Sandia solicits partners for surface patterning of GaN to allow epi lift-off

As a contractor to the US Department of Energy, Sandia National Laboratories is soliciting partners for commercializing a patent-pending surface patterning technology for metal-organic chemical vapor deposition (MOCVD) growth of gallium nitride (GaN) and related materials that enables lower defect densities and facilitates lift-off of epitaxial layers (solicitation number 11_356).

The technique may provide improved-quality GaN material for applications in solid-state lighting and high-power transistors, says Sandia. A layer of silica microspheres is deposited over a GaN seed layer on an inexpensive substrate such as silicon (Si).

As GaN is grown by MOCVD up through the interstices of the close-packed array of microspheres, strain is mitigated while threading dislocations bend and terminate at the microspheres, resulting in a uniform GaN layer with defect densities reduced by about two orders of magnitude over GaN grown on unpatterned surfaces in similar conditions.

The epitaxial layer can then be bonded to a thermally conductive material such as aluminum nitride (AlN) or diamond for better heat sinking, and released from the native substrate by selective etching of the microspheres. Sandia says that the etch process is less expensive and works on a greater variety of substrates than existing laser lift-off methods. The substrate can potentially be reused.

It is expected that commercial licenses may, on a competitive basis, grant exclusive rights in pre-negotiated, defined fields of use for reasonable consideration to qualified interested parties. Partnerships to commercialize the technology may also take the form of Cooperative Research and Development Agreements (CRADAs) or non-exclusive commercial licenses.

The deadline for responses to the solicitation is 3 March (the primary Point of Contact is Dan Allen: dgallen@sandia.gov).

Tags: GaN Epi lift-off MOCVD

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