Title :
The effect of hot carriers on the operation of CMOS active pixel sensors
Author :
Ching-Chun Wang ; Sodini, C.G.
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., MIT, Cambridge, MA, USA
Abstract :
Excess minority carriers induced by hot carriers in source follower transistors in active pixel sensors are experimentally observed using sensor arrays fabricated with a standard 0.35-/spl mu/m CMOS process. The number of carriers absorbed by photodiodes depends on bias conditions of the transistors and consequently becomes optical-signal dependent. A cascoded 4-T active pixel sensor is more sensitive to this effect due to its small sensing capacitance. Temperature varying experiments are performed to confirm this mechanism. The spatial distribution of the excess carriers is quantified to be within /spl sim/30 /spl mu/m around the source follower transistors. Suggestions on pixel design are provided.
Keywords :
CMOS image sensors; array signal processing; capacitance; hot carriers; minority carriers; photodiodes; 0.35 micron; CMOS active pixel sensors; bias conditions; excess minority carriers; hot carriers; optical-signal dependent; photodiodes; pixel design; sensing capacitance; sensor arrays; source follower transistors; spatial distribution; CMOS logic circuits; CMOS process; Capacitance; Capacitive sensors; Hot carriers; Optical sensors; Photodiodes; Sensor arrays; Sensor phenomena and characterization; Voltage;
Conference_Titel :
Electron Devices Meeting, 2001. IEDM '01. Technical Digest. International
Conference_Location :
Washington, DC, USA
Print_ISBN :
0-7803-7050-3
DOI :
10.1109/IEDM.2001.979569