AVS 50th International Symposium
    Electronic Materials and Devices Tuesday Sessions
       Session EM+SC-TuP

Paper EM+SC-TuP12
The Analysis on the Origin of High Resistivity in Polycrystalline CdZnTe Thick Films

Tuesday, November 4, 2003, 5:30 pm, Room Hall A-C

Session: Poster Session
Presenter: K.H. Kim, Korea University
Authors: K.H. Kim, Korea University
S.Y. Ahn, Korea University
M.H. Kim, Korea University
Y.J. Park, Korea University
K.N. Oh, Korea University
S.U. Kim, Korea University
Correspondent: Click to Email
The CdZnTe have an inherently high stoping power, an excellent carrier transport property, and relatively wide band gap energy. Therefore detectors using this materials have the potential for sufficient X-ray sensitivity and DQE at a sufficiently low leakage current.@footnote 1@ Although research results have been presented on single crystal CdTe and CdZnTe detectors with small sized silicon readout devices, it would be difficult to apply these results to large area flat-panel detectors. Alternatives of single crystal, we have grown large area ( 10 x 10 cm @super 2@ ) polycrystalline CdZnTe films by thermal evaporation method. The thickness, average grain size and Zn composition was 150 µm , 3 µm and 4%. Resisitivity of CdZnTe films is in the order of 2 x 10@super 9@ @Omega@cm which is comparable that of CdZnTe single crystal samples. In X-ray detectors, high leakage current limits the maximum integration time of the a-Si array for X-ray imaging applications so that high resistivity receptor material is required. Recent reports have identified deep level defects which are likely to be associated with semi-insulating property.@footnote 2@ Based on multiple trapping model, the localized state distributions of high resistivity polycrystalline CdZnTe from TOF (time of flight) transient current are examined using Laplace transform and Tikhonov reularization methods.@footnote 3@ We found 3 different deep localized states above valence band related to the resistivity. In TOF measurements, indium was used as top electrode to form Schottky type cotact to prevent carrier injection. @FootnoteText@@footnote 1@ S. Tokuda, H. Kishihara, S. Adachi, T. Sato, Y. Izumi, O. Teranuma, Y. Yamane, and S. Yamada, Proceedings of SPIE Vol. 4682 , 30 (2002)@footnote 2@ A. Zumbiehl, S. Mergui, M. Ayoub, M. Hage-Ali, A. Zerrai, K. Cherkaoui, G. Marrakchi, Y. Daricim, Material Science and Engineering B 71, 297 (2000)@footnote 3@ J. Weese , Comput. Phys. Commun. 69, 99 (1992).