Silicon-based long wavelength photodetectors

Three types of Si-based photodetectors (PD) operating at long wavelength were introduced: the strained SiGe/Si multi-quantum-wells PD and Ge/Si islands PD with resonant cavity enhanced (RCE) structure, Ge p-i-n PD on silicon and SOI, Ge/Si avalanche photodetectors (APDs) with separate absorption, charge and multiplication (SACM) structure. The strained SiGe/Si MQW RCE PD and Ge/Si islands RCE PD has a threefold enhanced responsivity compared with the conventional PD without a resonant cavity. The Ge p-i-n PD on SOI has a responsivity of 0.65 A/W at 1.31µm and 0.32 A/W at 1.55µm. The 3dB bandwidth is 13.3GHz at reverse bias of 3 V. The Ge/Si SACM APD operating at 1310 nm have a responsivity of 4.4A/W (with a gain of 8.8) biased at 90% of break voltage.