Method for production of free-standing polycrystalline boron phosphide film
AssigneeThe United States of America as represented by the United States Department of Energy
InventorsRichard J. Baughman, David S. Ginley
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Abstract
A process for producing a free-standing polycrystalline boron phosphide film comprises growing a film of boron phosphide in a vertical growth apparatus on a metal substrate. The metal substrate has a coefficient of thermal expansion sufficiently different from that of boron phosphide that the film separates cleanly from the substrate upon cooling thereof, and the substrate is preferably titanium. The invention also comprises a free-standing polycrystalline boron phosphide film for use in electronic device fabrication.
Claims8
A process for producing a free-standing boron phosphide film comprising the sequential steps of:
- (1) heating a metal substrate, selected from the group consisting of titanium, molybdenum, tantalum or tungsten, in a vertical growth apparatus to a temperature of about 650.degree.-1050.degree. C.;
- (2) flowing reactant gases over said metal substrate thereby growing a boron phosphide film thereon by chemical vapor deposition, the flow time being sufficient to grow a boron phosphide film of a predetermined thickness on said substrate;
- and (3) cooling said substrate and grown boron phosphide film to cause separation of said boron phosphide film from said substrate as a result of the difference in rate of contraction of said metal substrate with respect to said boron phosphide film thereby producing a free-standing crystalline boron phosphide film, said difference in rates of contraction on cooling being sufficient to cause separation of the substrate from the film.
Dependencies are inferred from the claim text.