Deposition of n-type nanocrystalline SiC films and current transport mechanisms in nanocrystalline SiC/crystalline Si heterojunctions

Phosphorus doped n-type nanocrystalline silicon carbide (nc-SiC) films were deposited on crystalline Si (c-Si) substrates at a low substrate temperature using helicon wave plasma chemical vapor deposition techniques. The current transport behaviors of nc-SiC/c-Si heterojunctions were measured in the temperature range of 100–290 K. It has been shown that the deposited SiC films reveal a high crystalline degree in 6H polytype and the fabricated nc-SiC/c-Si diode shows a typical abrupt heterojunction with good rectifying performance. The transport current satisfies a recombination-tunneling mechanism at forward bias, in which the recombination process determines the current in a small bias voltage value range, while the tunneling process becomes dominant when the voltage is higher than 2.5 V. Meanwhile an inversion behavior exists at low temperature regions in the current–voltage plot due to series resistance. At reverse bias, the current behavior is mainly controlled by the thermal emission of minority carries and their subsequent multi-step tunneling through defect states at the interface.