Evolution in the Electronic Structure of Polymer-derived Amorphous Silicon Carbide

The electronic structure of polymer-derived amorphous silicon carbide pyrolyzed at different temperatures was investigated by combining measurements of their temperature-dependent conductivity and optical absorption. By comparing the experimental results with theoretical models, the parameters such as conduction band, band-tail, defect energy, and Fermi energy were determined. The results revealed that band gap and band-tail width decreased with increasing pyrolysis temperature. Furthermore, it was found that electrons transport followed a band-tail hopping mechanism, rather than variable range hopping. These results were discussed in accordance with the microstructural evolutions of the material.