Silicoboron-carbonitride ceramics: A class of high-temperature, dopable electronic materials

The structure and electronic properties of polymer-derived silicoboron-carbonitride ceramics are reported. Structural analysis using radial-distribution-function formalism showed that the local structure is comprised of Si tetrahedra with B, C, and N at the corners. Boron doping of SiCN leads to enhanced p-type conductivity (0.1 Ω ¹cm^-1 at room temperature). The conductivity variation with temperature for both SiCN and SiBCN ceramics shows Mott's variable range hopping behavior in these materials, characteristic of a highly defective semiconductor. The SiBCN ceramic has a low, positive value of thermopower, which is probably due to a compensation mechanism.