Simulation and analysis of P+/N SPAD for 3D imaging

In this paper, a P⁺/N Single photon avalanche diode (SPAD) was selected to compare the performance of P⁺/N-well, P⁺/SEN and P⁺/DNW SPADs by varying the doping concentration of the N region. The performance characteristic, such as avalanche characteristic, Spectral response, AC response and Quantum efficiency were simulated by Silvaco TCAD. Simulations show that, lightly doped N region will improve the responsivity in the longer wavelength making the spectral response turns to the long wavelength, achieve larger bandwidth and the internal quantum efficiency of the SPAD improves significantly when the biased voltage enlarges for very weak light detection. For P⁺/N-well, P⁺/SEN and P⁺/DNW SPADs, the doping concentration level of Deep NWELL (DNW) is the lowest, the P⁺/DNW SPAD is more efficient to detect the photon of 850nm wavelength for 3D imaging.