Grain-boundary interfacial states in BeO-doped SiC ceramics: Photoisothermal capacitance transient spectroscopy

Abstract

Interfacial states at grain boundaries in BeO-doped SiC ceramics were characterized using the isothermal capacitance transient spectroscopy (ICTS) method. ICTS signals due to the interfacial states were detectable above 160 °C in the dark. By irradiating visible light, the capacitance increased and the behavior of C-V characteristics changed compared to those in the dark; in addition to this, the ICTS signals could be observed at room temperature. The wavelength dependence of ICTS signals showed that the signals disappeared above 950 nm. This result suggested that adiabatic excited states of holes captured at grain boundaries were located at about 1.3 eV above its ground state, which was different from thermally excited states determined by the ICTS in the dark, i.e., 0.9 eV.