A Wide Depletion Region Single Photon Avalanche Diode

Single photon avalanche diode (SPAD) has achieved a wide range of applications in the field of single-photon detection by virtue of their single-photon level sensitivity, ultra-high speed, and other characteristics. Front-illuminated SPAD has gained widespread attention in recent years due to their advantages of low fabrication cost, simple process, and compatibility with mature CMOS. However, the photon detection performance of conventional front-illuminated SPAD is often limited by the issues such as narrow depletion region of planar avalanche junction. In this paper, a wide depletion region silicon-based SPAD with a pixel radius of 2.55 μm is designed and simulated using TCAD software and several electrical parameters and optoelectronic characteristics has been obtained. The SPAD creates several high values of electric field through several semicircular N-type regions. With a reverse bias above the breakdown voltage, several semicircular areas with high electron breakdown probability appear near the top surface of the device. These areas help improve the photon detection probability. Finally, according to the simulation results, the device has a peak photon detection probability of 45% and a DCR value of 1180cps while Vex=5V, wavelength = 450nm.