High-bias current-voltage-temperature characteristics of undoped rf magnetron sputter deposited boron carbide (B5C)/p-type crystalline silicon heterojunctions

The high-bias behaviour of the dark forward and reverse current-voltage (I-V) characteristics of an undoped radio frequency (rf) magnetron sputter deposited boron carbide (p-B5C)/p-type crystalline silicon heterojunction has been investigated at different ambient temperatures (130-300 K). The experimental forward current-voltage-temperature (I-V-T) characteristics indicate that the non-ohmic bulk conduction mechanisms operable in the highly resistive polycrystalline B5C counterpart material of this heterojunction largely determine the behaviour of its forward current at high-bias voltages (>0.3 V). The hopping conduction model of Apsley and Hughes for a flat density of localized energy states (Apsley N and Hughes H P 1975 Phil. Mag. 31 1327) can be utilized to elucidate the bias dependence of the measured heterojunction forward current over an extended bias-voltage range (0.4-2.7 V) at temperatures below 260 K. On the other hand, the junction-like conduction processes occurring in the depletion region should limit the high-bias behaviour of the measured heterojunction reverse current. Bardeen's model for a modified Schottky-like barrier at the p-B5C/p(+)-Si interface can be satisfactorily applied to describe the reverse current-voltage characteristics at bias voltages larger than 0.4 V.