Avalanche Photodiode Array Device Design And Analysis

Unmodified CMOS processes have been successfully employed to produceexcellent image sensors, rivaling the performance of the best CCDs. However, significantimprovements in sensitivity have not been achieved. To overcome the transistor-inducednoise limitations of solid state image sensors at low light levels, the avalanchemultiplication can be employed to improve the sensitivity of CMOS image sensors.APDs have found applications in single photon counting and low light leveldetection. APD structures in a standard 1.2μm BiCMOS process have been realized byAlice Biber and Peter Seitz in Swiss Federal Institute of Technology, Switzerland.This paper studies the avalanche photodiodes image sensor in standard siliconBiCMOS technology. CCD and CMOS image sensors are described. The differencebetween CCD and CMOS image sensors are compared and noise is the main drawbacksin low light level of the solid image sensor. The characterization and working mode ofAPDs are studied, especially the characterization of the GM-APDs and the avalanchebreakdown of the PN junction. Noise characterization of APDs is studied. The noisemodels of photon-diode and avalanche photon-diode are realized and the detection ofAPD is studied. The internal distribution of voltage and carriers are analyzed bynumerical analysis, and the distribution curves are got by C computer program in steadyconditions, which is a foundation of further research and analysis of the more complexdevice.