Design and Numerical Verification of a Gate-Controlled Lateral Thyristor for Low-Light Level Detection

Thyristors operated at switching point are highly sensitive to external physical signals such as light or temperature. However, due to the instability of sensitive switching point, conventional thyristors are commonly used as optical switches and hardly applied for low-light level detection. In this work, a silicon-based gate-controlled lateral thyristor (GC-LT), which takes advantage of high sensitivity at low-light, is studied by numerical simulation. A thyristor photodetector circuit and a novel super-off Reset operation method are also proposed to bias the GC-LT over the switching point quickly and allow the photodetector to be operated in a monotonic dynamic multi-sampling mode to achieve high sensitivity to low-light. Simulation results show that the Reset time can be shortened to $ < 10~\mu \text{s}$ without trigging the GC-LT. The trigger time of the photodetector is sensitive to the optical power density ranging from $1\times 10^{-9}$ to $2.5\times 10^{-6}$ W/cm2. Furthermore, the average optical gain is about 8.0-6.3, approximately one order of magnitude higher than that of the Si pinned photodiode.