Photosensitive hole transport in Schottky-contacted Si nanomembranes

摘要

When Schottky-contacted Si nanomembranes (SiNMs; 27 nm in thickness) are exposed to light it is mainly the hole transport responding sensitively to the illumination. The electron transport on the contrary remains rather unaffected by the exposure, which cannot be explained by a simple creation of electron-hole pairs. We attribute this effect to the holes activated from SiNM surfaces, which strongly supports the existence of surface doping in SiNMs [P. P. Zhang, E. Tevaarwerk, B. N. Park, D. E. Savage, G. K. Celler, I. Knezevic, P. G. Evans, M. A. Eriksson, and M. G. Lagally, Nature 439, 703-706 (2006)]. Our work suggests that the surfaces play a decisive role when creating and designing optoelectronic devices based on SiNMs.