Electrical transport properties of the Si-doped cubic boron nitride thin films prepared by <i>in situ</i> cosputtering

Abstract

Si-doped cubic boron nitride (c-BN) films with various Si concentrations were achieved by in situ cosputtering during ion beam assisted deposition. Effects of the Si concentration and rapid thermal annealing (RTA) conditions on the electrical transport properties of Si-doped c-BN thin films were investigated systematically. The results suggest that the optimum RTA condition is at the temperature of 1000 °C for 3 min. The resistance of Si-doped c-BN films gradually decreases as the Si concentration increases, indicating an electrical doping effect of the Si impurity. The temperature dependent electrical conductivity of the Si-doped c-BN films suggests that different conduction mechanisms are dominant over the different temperature ranges. Based on the Davis–Mott model, we propose that the extended-state conduction, band tail-state conduction and short-range hopping conduction are responsible for the respective temperature ranges. In addition, the reduction in activation energy of Si impurities is observed as the Si concentration increases.