Evidence for bistable defects in 6H-SiC

Electrical properties of nitrogen (N) doped 6H-SiC have been investigated throughout the temperature range from 10 K to 550 K. Scattering mechanisms in different temperature regions have been investigated. Persistent photoconductivity (PPC) has also been observed. Because of the existence of PPC, we have been able to vary continuously the electron concentration, n, within a single sample at fixed temperatures, through the variation of the excitation phonon dose. The electron mobility as a function of the electron concentration, μ(n), has been measured at fixed temperatures. The temperature dependence of the photogenerated electron concentration in the PPC state, {up triangle, open}n, has also been investigated. Experimental results indicate that the defect centers respobsible for the PPC effect are bistable in nature, which is analogous to the DX centers in AlGaAs.