Vapor transport deposition of large-area polycrystalline CdTe for radiation image sensor application

Vapor transport deposition (VTD) process delivers saturated vapor to substrate, resulting in high-throughput and scalable process. In addition, VTD can maintain lower substrate temperature than close-spaced sublimation (CSS). The motivation of this work is to adopt several advantages of VTD for radiation image sensor application. Polycrystalline CdTe films were obtained on 300 mmx300 mm indium tin oxide (ITO) coated glass. The polycrystalline CdTe film has columnar structure with average grain size of 3 mu m similar to 9 mu m, which can be controlled by changing the substrate temperature. In order to analyze electrical and X-ray characteristics, ITO-CdTe-Al sandwich structured device was fabricated. Effective resistivity of the polycrystalline CdTe film was similar to 1.4x109Ocm. The device was operated under hole-collection mode. The responsivity and the mu t product estimated to be 6.8 mu C/cm2R and 5.5x107 cm2/V. The VTD can be a process of choice for monolithic integration of CdTe thick film for radiation image sensor and CMOS/TFT circuitry. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)