Optical And Electrical Performance Of Schottky Diodes On Low Loss Soi Waveguides

Thin layers of nickel (Ni) and palladium (Pd) are used to form Schottky barrier photodiodes on silicon-on-insulator optical rib waveguides defined by the local oxidation of silicon technique. Optical loss and attenuation due to the metallic layers on the waveguides are estimated by simulations followed by experimental verification. Loss increases with increasing metal thickness until a plateau is reached at a thickness of approximately 50 nm. Higher optical loss is observed for the transverse magnetic mode compared to that for the transverse electric mode. The dark current density of all the devices is less than 10(-6) Acm(-2) at 1 V reverse bias. The TM mode responsivity is 4.7 mA/W and 0.33 mA/W for 0.5 mm long Ni/nSi and Pd/nSi at 1310 nm wavelength, respectively. This work demonstrates great potential for simple sub-bandgap photodetectors for silicon photonics. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement