Active Pixel Sensor Using a 1×16 Nano-Wire Photodetector Array for Complementary Metal Oxide Semiconductor Imagers

Abstract

In this paper, a novel photodetector using an N-channel metal oxide semiconductor field effect transistor (NMOSFET) with a 30 nm-wide silicon nano-wire is described. The photodetector was fabricated on silicon-on-insulator (SOI) substrate and its wire was patterned by optical lithography, electron beam lithography and thermal oxidation. At room temperature, the device has similar IDS-VDS characteristics to a general NMOSFET when incident light is supplied instead of the gate voltage. A maximum responsivity of higher than 1×102 A/W and optical transient time of 80 µs have been obtained. Additionally, for the purpose of demonstrating the feasibility of the new device application, a 1×16 complementary metal oxide semiconductor (CMOS) active pixel sensor (APS) connected with the novel photodetector array was also designed and fabricated using 1-poly and 2-metal 1.5 µm CMOS technology. It is confirmed that this photodetector with high sensitivity as well as nano-scaled area could be applied to an image acquisition system for low illumination level.