Journal of the American Ceramic Society, Vol.102, No.10, 6038-6047, 2019
Electron transport behavior of polymer-derived amorphous silicoboron carbonitrides
Electron transport behavior of polymer-derived amorphous silicoboron carbonitride (a-SiBCNs) ceramics was studied by measuring DC/AC conductivities and optical absorption as functions of the temperature. Structural information of materials was investigated by combining X-ray diffraction (XRD), nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and electron paramagnetic resonance (EPR) techniques. Conductive mechanisms and electronic structure of the materials (eg, hopping mechanism, conduction band, band-tail, and defect energy) were deduced by fitting experimental results to theoretical models. Results revealed that DC/AC conduction of materials followed band-tail hopping mechanism instead of previously assumed variable-range hopping mechanism. Hopping mechanism, associated with overlapped band-tail and defect levels, was likely originated by the presence of certain number of defects and highly disordered structure of materials. The content of donor defects in materials was considered to have great influence on the type of electronic mechanism. These results were discussed in line with microstructural evolution of materials.