Analysis and Design of STI-bounded Single Photon Avalanche Diode with Low Breakdown Voltage

Single photon avalanche diodes (SPADs) which are based on impact ionization effect have been widely applied to detect the ultra-weak optical signals. Conventional SPAD devices have a high breakdown voltage due to the undeveloped manufacturing processes, which causes a high power dissipation. This paper proposes a structure of single photon avalanche diode with shallow trench isolation (STI) based on MXIC 0.18 µm complementary metal oxide semiconductor (CMOS) process. A series of simulations performed by Silvaco-Technology Computer Aided Design (TCAD) were done to verify the fundamental working principle about SPAD. The two-dimensional simulation results include the volt-ampere characteristics, darkcurrent, electric field distribution, current path, impact ionization distribution and spectral response curve of the SPAD device. And the simulation results demonstrate that the proposed structure has a low breakdown voltage (11.5 V). The response peak wavelength is 500 nm, which can be applied to detecting the visible light.