DocumentCode
1755264
Title
Direct-Conversion CMOS X-Ray Imager With 
Pixels
Author
Parsafar, Alireza ; Scott, Christopher C. ; El-Falou, Abdallah ; Levine, Peter M. ; Karim, Karim S.
Author_Institution
Dept. of Electr. & Comput. Eng., Univ. of Waterloo, Waterloo, ON, Canada
Volume
36
Issue
5
fYear
2015
fDate
42125
Firstpage
481
Lastpage
483
Abstract
We report a monolithic direct-conversion X-ray imager capable of detecting diagnostic level X-rays. The imager is constructed by combining a custom 32×32 CMOS four-transistor active pixel sensor (4T APS) array with an amorphous selenium photoconductive layer deposited on top of the array via a post processing step. A 4T APS with an explicit per-pixel integration capacitor is employed to increase the pixel dynamic range. Under dark conditions, an input-referred electronic noise of <;90 electrons (rms) is estimated based on measured noise data for a 40-ms integration time. The very first X-ray images of copper and stainless-steel objects are included to demonstrate the performance of what is, to the best of our knowledge, a direct-conversion X-ray imager with the smallest pixel pitch reported to date.
Keywords
CMOS image sensors; X-ray apparatus; X-ray detection; X-ray imaging; capacitors; noise; selenium; semiconductor counters; CMOS four-transistor active pixel sensor array; Se; amorphous selenium photoconductive layer; copper objects; dark conditions; diagnostic level X-rays; explicit per-pixel integration capacitor; input-referred electronic noise data; integration time; monolithic direct-conversion CMOS X-ray imager; pixel dynamic range; pixel pitch; post-processing step; stainless-steel objects; Arrays; CMOS integrated circuits; Capacitors; Noise; Photonics; Spatial resolution; X-ray imaging; Amorphous semiconductors; CMOS image sensors; X-ray detectors; active pixel sensors;
fLanguage
English
Journal_Title
Electron Device Letters, IEEE
Publisher
ieee
ISSN
0741-3106
Type
jour
DOI
10.1109/LED.2015.2410304
Filename
7055286
Link To Document