1T Pixel Sensor Based on FDSOI Transistor Optical Back Biasing

This paper presents the study of a monolithically integrated FDSOI-based pixel sensor, called FDPix. The FDPix consists in cointegrating a photodiode in the substrate of an fully depleted silicon on insulator (FDSOI) transistor. Its principle of operation is based on optical back biasing of FDSOI transistor characteristics under photodiode illumination. A reset mechanism is demonstrated using the back gate of the transistor and can be applied commonly to all pixels, allowing a very small footprint. The investigation is carried out by means of TCAD simulation, analytical modeling, and optoelectrical characterization to evaluate the sensor's characteristics and to optimize the device technological parameters. The pixel exhibits two responses, linear response at low intensities and logarithmic response at high intensities, achieving a high dynamic range (DR) of 120-130 dB.