Semiconductor‐conductor transition of pristine polymer‐derived ceramics SiC pyrolyzed at temperature range from 1200°C to 1800°C

Abstract

Abstract This paper studies the effect of pyrolysis temperature on the semiconductor‐conductor transition of pristine polymer‐derived ceramic silicon carbide (PDC SiC). A comprehensive study of microstructural evolution and conduction mechanism of PDC SiC pyrolyzed at the temperature range of 1200°C‐1800°C is presented. At relatively lower pyrolysis temperatures (1200°C‐1600°C), the carbon phase goes through a microstructural evolution from amorphous carbon to nanocrystalline carbon. The PDC SiC samples behave as a semiconductor and the electron transport is governed by the band tail hopping (BTH) mechanism in low pyrolysis temperature (1300°C); by a mixed mechanism driven by band tail hopping and tunneling at intermediate temperature (1500°C). At higher pyrolysis temperatures (1700°C‐1800°C), a percolative network of continuous turbostratic carbon is formed up along the grain boundary of the crystallized SiC. The samples demonstrate metal‐like conductive response and their resistivity increases monotonically with the increasing measuring temperature.