Low-dark-count-rate CMOS SPAD photoelectric device

Abstract

The invention provides a low-dark-count-rate CMOS SPAD photoelectric device. A P-well layer is added based on a routine P+ / N-well type SPAD structure. The P-well layer is arranged between the P+ layerand the N-well layer. Furthermore, an N-well clearance is utilized as a virtual protecting ring of the structure; namely N-wells are added at two sides of a PN junction, wherein the structure is shown in the attached figures of an abstract. An incident photon is incident into the device and is attracted at the central N well, and furthermore a photon-generated carrier is generated. The P-well layer and the N-well layer are utilized at two sides of the PN junction. Hereon an avalanche junction is a P-well / N-well junction. Because the avalanche junction is a lightly doped avalanche junction, width of a depletion region increases, and probability of interband tunneling of the carries is reduced, thereby reducing the dark counting rate. Furthermore the virtual protecting ring is used for suppressing edge breakdown of the PN junction. The forming principle of virtual protection is characterized in that transverse diffusion exists between adjacent N-wells and therefore the N- virtual protecting ring is formed at the PN junction. The low-dark-count-rate CMOS SPAD photoelectric device is designed at two aspects of the protecting ring and the depletion region width, dark current of the device is reduced, thereby reducing the dark count rate.

Description

technical field [0001] The invention belongs to the technical field of single photon detection, relates to the structural design of an APD photoelectric device, in particular to the design of a CMOS SPAD photoelectric device with a new structure and low dark count rate. Background technique [0002] Single Photon Avalanche Diode (Single Photon Avalanche Diode), also known as SPAD, is an avalanche photodiode (Avalanche Photodiode) working in Geiger mode (working voltage greater than breakdown voltage). Since SPAD works in Geiger mode and can detect a single photon, the device has great application prospects in quantum communication technology, fluorescence lifetime imaging, three-dimensional imaging technology and other fields. [0003] The device structure of CMOS SPAD can be divided into two categories according to the type of its guard ring. One is a diffused guard ring structure, that is, a lightly doped N-well or P-well is used at the edge of the PN junction. The dark c...

AI Technical Summary

Problems solved by technology

Simple scaling down of the traditional SPAD device structure cannot achieve a low dark count rate while maintaining a high fill factor and high photon detection efficiency

Images