Optoelectronic Characterization of Infrared Photodetector Fabricated on Ge-on-Si Substrate

Abstract

We report on the optoelectronic characterization of Ge p–i–n infrared photodetector fabricated on Ge-on-Si substrate using rapid thermal chemical vapor deposition (RTCVD). The phosphorous doping concentration and the root mean square (RMS) surface roughness of epitaxial layer was estimated to be 2 × 1018 cm–3 and 1.2 nm, respectively. The photodetector were characterized with respect to their dark, photocurrent and responsivities in the wavelength range of 1530–1630 nm. At 1550 nm wavelength, responsivity of 0.32 A/W was measured for a reverse bias of 1 V, corresponding to 25% external quantum efficiency, without an optimal antireflection coating. Responsivity drastically reduced from 1560 nm wavelength which could be attributed to decreased absorption of Ge at room temperature.