NSF: An investigation into the properties of B12As2, B4C and their heterostructures

The properties of the boron-rich icosahedral boride semiconductors B12As2 and B4C lie at the extremes in many categories such as high melting temperatures, hardness, and Seebeck coefficients. Consequently, this novel material class is attractive for applications such as high temperature as well as space electronics, neutron detectors, thermoelectronics and betavoltaic cells, the latter ones for the conversion of heat and nuclear energy, respectively, to electrical energy. A collaborative research effort between Kansas State University, SUNY and Bristol University is proposed to advance the synthesis and characterization of these new materials, as detailed insight is necessary to understand the effects of growth parameters on the structure and composition, and their effects on properties. The US side of the work would be supported by NSF, the UK side by EPSRC with corresponding proposals submitted to NSF and EPSRC. At Kansas State University, the materials will be grown as epitaxial films, bulk crystals and heterostructures. At SUNY, detailed structural characterizations will be performed to understand defect and defect generation in this new material system. At the University of Bristol, Raman scattering, optical and thermopower characterization will determine the properties of this new material system. We will be the first to combine the icosahedral borides into heterostructures to realize new properties to create new applications with potential great benefit to, for example, high temperature thermoelectric applications.