Flow of space-charge-limited currents in cubic boron nitride

Current-voltage characteristics of polycrystal cubic nitride samples are studied at various temperatures. The samples were undoped crystals obtained by the method of direct phase transformation of pyrolytic graphite-like boron nitride and crystals doped with sulfur to obtain n-type conductivity. The current-voltage characteristics consist of three different parts: linear and quadratic segments and the region of dramatic increase in the current, which indicates the existence of space-charge-limited currents. The activation energy, E_t, and concentration of the trapping centers, N_t, are determined. The experimental data obtained allowed us to calculate, for the first time, the mobility and concentration of free carrier in the conduction band. Possible mechanisms giving rise to a dramatic increase in are made the current on the current-voltage characteristics are discussed.