Method of making an icosahedral boride structure

A method for fabricating thin films of an icosahedral boride on a silicon carbide (SiC) substrate is provided. Preferably the icosahedral boride layer is comprised of either boron phosphide (B12P2) or boron arsenide (B12As2). The provided method achieves improved film crystallinity and lowered impurity concentrations. In one aspect, an epitaxially grown layer of B12P2 with a base layer or substrate of SiC is provided. In another aspect, an epitaxially grown layer of B12As2 with a base layer or substrate of SiC is provided. In yet another aspect, thin films of B12P2 or B12As2 are formed on SiC using CVD or other vapor deposition means. If CVD techniques are employed, preferably the deposition temperature is above 1050° C., more preferably in the range of 1100° C. to 1400° C., and still more preferably approximately 1150° C.