The dark current suppression of black silicon photodetector by a lateral heterojunction

Abstract

Femtosecond laser hyperdoped silicon, known commonly as black silicon (b-Si), has attracted substantial interest from various fields due to its high absorptance and responsivity ranging from visible to near-infrared wavelengths. However, due to the non-uniformity of b-Si layer and the lattice defects present in it, the processing technique used presently introduces high noise in devices manufactured using b-Si. In this study, a lateral heterojunction is designed and manufactured at the b-Si and silicon interface to restrain the leakage current. Precisely, the lateral structure could support the b-Si photodetector in suppressing the dark current to 783 nA at a bias of -5 V, quite low in terms of orders of magnitude compared to that for the vertical ones. Simultaneously, the photo-to-dark current ratio of 155 is obtained at the same bias voltage with a pertinent external quantum efficiency (EQE) of 371%. Riding on the advantages of low noise, high signal-to-noise ratio, and high sensitivity, this work shows promising prospects for the application of b-Si-based photodetectors toward large-scale integration in optical-electronics or flip-chip interconnection systems. • The dark current of b-Si photodetector is suppressed by a lateral heterojunction. • The detector exhibits a high photo-to-dark current ratio at reverse bias voltage. • The photoconductive gain is achieved for a wide coverage of wavelength.