Novel Photosensitive Dielectric-Based Image Sensor with Both High Signal-to-Noise Ratio and High Fill Factor

Abstract

Driven by the pursuit of a higher signal-to-noise ratio (SNR), CMOS imagers have evolved from initial passive pixel sensor (PPS) with one transistor (1T) to 3T, 4T, or 5T active pixel sensors (APS) and then recently to digital pixel sensors (DPS). However, this evolution inevitably causes a lower and lower fill factor. Here, we innovatively designed a photodetector (PD) based on a photosensitive dielectric (PSD) strategy. The unique PSD layer works as an insulator in the dark and as a semiconductor under illumination, making the PD have a built-in 4T function consisting of memory, address, amplification, and reset. Further, we prepared a 16 × 16 one-PD (1D) APS array demo. The memory imaging, continuous imaging, power-off imaging, and trajectory tracing imaging functionalities were successfully demonstrated. This work provides a novel 1D APS structure with a built-in 4T function well handling the SNR-fill factor trade-off, paving a new path for a high-performance image sensor with good versatility and scalability.