Hybrid structure for efficiency enhancement of photodetectors

A nanoporous tapered silicon (Si) photonic crystal (PC) is realized. The PCs with this structure, which may be called hybrid PC-porous can significantly reduce the surface reflection over the broad wavelength range of 400-2000 nm. Moreover, the absorption enhances in this structure significantly. The PCs are fabricated by interference lithography and then nanoporous structure is applied on it using metal assisted chemical etching. The measured reflectance and absorption across a spectral range of 400-2000 nm are, approximately 3% and 96%, respectively. The improvement on the reflectance and absorption are about 90% and 70% compared to bare Si respectively; which is promising in the utilization of this structure for various applications. (C) 2012 Elsevier B.V. All rights reserved.