摘要
Active pixel sensor (APS) circuits are an alternate to passive pixel sensor (PPS) circuits, which, while common in CMOS technology, have yet to be incorporated into commercial amorphous silicon (a-Si) large-area imagers. A proof-of-concept 64 x 64 APS array for low-exposure medical X-ray imaging is fabricated in a-Si technology and mated with an amorphous selenium photoconductor. Modulation transfer MTF) response and transient response for the APS imager indicate significant charge trapping at the top insulator/a-Se interface. MTF response indicates an effective fill factor of 94.5% for a geometric fill factor of 57% at an electric field strength of 10 V/mu m. Signal-to-noise ratio (SNR) performance from the prototype imager is comparable to a state-of-the-art commercially available a-Si PPS X-ray imager for X-ray exposures down to 1.5 mu R using an RQA5 standard fluoroscopic characterization beam. Pixel design and fabrication process improvements are suggested to improve the SNR performance of the APS imager below 1.5 mu R.
- 出版日期2010-11