Random Telegraph Signal in n+/p-Well CMOS Single-Photon Avalanche Diodes

In this article, in addition to two commonly known noise parameters-dark count rate (DCR) and afterpulsing (AP)-we explore another interesting phenomenon-random telegraph signal (RTS) noise-during the transitional phase of the avalanching process. We present the properties of the RTS noise and their dependence on the biasing voltage and temperature. An analytical model is used to extract the dimension of the defects in the depletion region from the variation of the RTS noise current amplitude with biasing voltage. By comparing the DCR and AP of single-photon avalanche diode (SPAD) samples with different defect dimensions derived from the RTS noise properties, a trend that the SPAD with a larger defect dimension shows a higher DCR and AP is found.