Electrical characterization of nanocrystalline carbon-silicon heterojunctions

Nanocrystalline carbon (nc-C) films were grown by magnetron sputtering on n-type Si substrates at room temperature and at substrate bias voltage -200 V. The electrical transport properties of nc-C/n-Si heterojunctions are investigated by current-voltage measurements at various temperatures and capacitance-voltage measurements at room temperature. The results indicate that the forward conduction is determined by thermionic emission over a potential barrier of height 0.3 eV at temperatures above 180 K. At lower temperatures and low currents, multistep tunneling current dominates. At low reverse voltages, the reverse conduction is dominated by current generated within the depletion region, while at higher voltages the current is due to Poole-Frenkel emission. (C) 2001 American Institute of Physics.