Simulation of SiGe/Si single photon avalanche photodiode

The design of a CMOS-technology compatible SiGe/Si single photon avalanche photodiode was presented. The influence of doping condition on electric field distribution, the bandwidth characteristic and the quantum efficiency of detector were discussed in detail. A shallow-junction, Geiger-mode avalanche photodiode to provide single-photon-counting capability at 1.06 m with a low-breakdown voltage(30 V) was designed. A separate absorption and multiplication(SACM) structure was used to fabricate the SiGe/Si avalanche photodiodes, where Si material was taken as the multiplication region. Taking advantage of the higher silicon carrier ionization coefficient, noise was reduced, the quantum efficiency of SiGe detector is 4.2% at 1.06 m, which has a 4 times enhancement compared with the Si detector. Simulation results indicate the optimum doping conditions can realize a suitable e-field distribution, thus obtaining good bandwidth characteristic at the required breakdown voltage of the APD.