PMOSFET-Type Photodetector with High Responsivity for CMOS Image Sensor

In this paper, a new photodetector using a PMOSFET-type photodetector with a transfer gate has been designed and fabricated using a 0.35 mum standard CMOS technology. The photodetector is composed of a floating gate that is tied to an n-well and a transfer gate. The transfer gate controls the photocurrent flow by controlling the barrier for holes in the PMOSFET-type photodetector. The designed photodetector has similar Ids-Vds characteristics as those of a general PMOSFET when the incident light power, instead of the gate voltage, is varied. The area of the proposed photodetector is 3.8 mum times 5.7 mum and the responsivity is larger than 2.7 times 10² AAV at a wavelength of 632.8 nm.