Direct Thermal Growth of Large Scale Cl-doped CdTe Film for Low Voltage High Resolution X-ray Image Sensor.

ABSTRACT: Polycrystalline cadmium telluride (CdTe) X-ray photodetector with advanced performance was fabricated in a Schottky diode form by direct thermal deposition (evaporation) on pixelized complementary metal oxide semiconductor (CMOS) readout panel. Our CdTe X-ray detector shows such a variety of benefits as relatively low process temperature, low cost, low operation voltage less than 40?V, and higher sensitivity and spatial resolution than those of commercial a-Se detectors. CdTe has cubic Zinc Blende structure and maintains p-type conduction after growth in general. For low voltage operation, we succeeded in Cl doping at all stage of CdTe film deposition, and as a result, hole concentration of p-type CdTe was reduced to ~10¹²?cm^-3 from ~10¹⁵?cm^-3, and such concentration reduction could enable our Schottky diode with Ti electrode to operate at a reverse bias of less than 40?V. Our CdTe Schottky diode/CMOS pixel array as a direct conversion type imager demonstrates much higher resolution X-ray imaging in 7?×?9?cm² large scale than that of CsI/CMOS array, an indirect conversion imager. To our limited knowledge, our results on polycrystalline CdTe Schottky diode/CMOS array would be very novel as a first demonstration of active pixel sensor system equipped with directly deposited large scale X-ray detector.

SUBMITTER: Lee S 

PROVIDER: S-EPMC6172199 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature