Current Polarity Changeable Concentric MIS Tunnel Photodiode With Linear Photodetectivity via Inner Gate Biasing and Outer Ring Short-Circuit Operation

The coupling effect between neighbor electrodes in the concentric metal-insulator-semiconductor(p) tunnel diode (MIS(p) TD) was investigated. In the accumulation region, the diffusion current, resulting from the gradient of the electron concentration, is the dominant factor in the coupling effect. However, in the deep depletion region, the fringing field dominates. Based on the coupling mechanism, we propose a novel sensing method that measures the short-circuit current of the outer ring with the inner gate biasing. When the light intensity exceeds 100 lux, the short-circuit current increases linearly and switches from negative to positive at a specific threshold of light intensity, providing a significant advantage in photodetection. Moreover, the threshold is tunable by gate bias, and the linearity of the sensor ensures its accuracy and convenience. Additionally, biasing the outer ring to 0 V reduces power consumption.