Abnormal humidity-dependent electrical properties of amorphous carbon/silicon heterojunctions

Amorphous carbon (a-C) film/n-Si heterojunctions have been fabricated by pulse laser deposition, and their current-voltage characteristics have been investigated. The results show that the atmosphere relative humidity (RH) has a significant effect on the reverse bias I-V characteristics of the heterojunctions. For the low bias voltages, the resistance of the a-C/Si heterojunction decreases with the increase of the RH. However, when the applied voltage is greater than a threshold, the resistance of the a-C/Si heterojunctions increases with the increase of the RH. This humidity-dependent phenomenon is attributed to the charge transfer from the absorbed H2O molecular to a-C film. (C) 2010 American Institute of Physics. [doi:10.1063/1.3520493]