Transport mechanism of nanocrystalline-silicon film tunnelling diodes

Based on the research into the conduction mechanism of the hydrogenated nanocrystalline silicon (nc-Si:H) films, we have fabricated nanocrystalline-silicon film tunnelling diodes. The structure of the diode is Al/c-Si/nc-Si:H/Al, in which the nc-Si:H thin film is the active layer. A characteristic of local ordered structures was detected in the nc-Si:H film, which indicated that both ordered micro-zones and disordered regions existed in the film. In some diodes quantum staircases and quantum oscillation phenomena were observed in the I-V, -V and C-V curves at liquid nitrogen temperatures or below (<100 K). On the basis of energy level calculation, we consider that the current through the diode comes from two parts: in the ordered micro-zones of the active layer electrons transport via resonant tunnelling, while in the disordered regions resonant tunnelling will be smeared and the tunnelling current increases continually with increasing bias.