Defect-enhanced photo-detection at 1550 nm in a silicon waveguide formed via LOCOS

Abstract

We present the integration of a defect-enhanced photodiode with high sensitivity at 1550 nm with a silicon waveguide structure formed by the LOCOS (LOCal Oxidation of Silicon) process. The defects are introduced through a 4 MeV Si+ implantation followed by thermal treatment at 200–500 °C to form a sub-bandgap photo-response. A 100 nm polycrystalline silicon layer forms a self-aligned contact to the top of the ridge waveguide and provides efficient extraction of generated carriers. Processing conditions and device structure design have been varied to determine their influence on responsivity, insertion loss and leakage current. A 6 mm long optical power monitor is presented with responsivity of approximately 47 mA W−1 at −5 V bias for an absorption of 12 dB (∼0.003 A W−1 dB−1).