Single-crystalline B12As2 on m-plane (11¯00) 15R-SiC

Single crystal, heteroepitaxial growth of icosahedral B12As2 (IBA, a boride semiconductor) on m-plane 15R-SiC is demonstrated. Previous studies of IBA on other substrates, i.e., (111)Si and (0001)6H-SiC, produced polycrystalline and twinned epilayers. In contrast, single-crystalline and untwinned IBA was achieved on m-plane 15R-SiC. Synchrotron white beam x-ray topography, Raman spectroscopy, and high resolution transmission electron microscopy confirm the high quality of the films. High quality growth is shown to be mediated by ordered nucleation of IBA on (474) substrate facets. This work demonstrates that m-plane 15R-SiC is a good substrate choice to grow high-quality untwinned IBA epilayers for future device applications. Financial support from the National Science Foundation Materials World Network Program under Grant No. 0602875 and by the Engineering and Physical Science Research Council (EPSRC) under Grant No. EP/D075033/1 under the NSF-EPSRC Joint Materials Program is acknowledged. The SWBXT was carried out at Stony Brook Topography Facility (Beamline X19C) at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory (BNL), which is supported by the U.S. Department of Energy (D.O.E.) under Grant No. DE-AC02-76CH00016. Research carried out (in part) at the Center for Functional Nanomaterials, BNL, which is supported by the U.S. Department of Energy, Division of Materials Sciences and Division of Chemical Sciences, under Contract No. DE-AC02-98CH10886.