{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T16:31:43Z","timestamp":1774974703164,"version":"3.50.1"},"reference-count":156,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2011,5,9]],"date-time":"2011-05-09T00:00:00Z","timestamp":1304899200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In the last ten to fifteen years there has been much research in using amorphous and polycrystalline semiconductors as x-ray photoconductors in various x-ray image sensor applications, most notably in flat panel x-ray imagers (FPXIs). We first outline the essential requirements for an ideal large area photoconductor for use in a FPXI, and discuss how some of the current amorphous and polycrystalline semiconductors fulfill these requirements. At present, only stabilized amorphous selenium (doped and alloyed a-Se) has been commercialized, and FPXIs based on a-Se are particularly suitable for mammography, operating at the ideal limit of high detective quantum efficiency (DQE). Further, these FPXIs can also be used in real-time, and have already been used in such applications as tomosynthesis. We discuss some of the important attributes of amorphous and polycrystalline x-ray photoconductors such as their large area deposition ability, charge collection efficiency, x-ray sensitivity, DQE, modulation transfer function (MTF) and the importance of the dark current. We show the importance of charge trapping in limiting not only the sensitivity but also the resolution of these detectors. Limitations on the maximum acceptable dark current and the corresponding charge collection efficiency jointly impose a practical constraint that many photoconductors fail to satisfy. We discuss the case of a-Se in which the dark current was brought down by three orders of magnitude by the use of special blocking layers to satisfy the dark current constraint. There are also a number of polycrystalline photoconductors, HgI2 and PbO being good examples, that show potential for commercialization in the same way that multilayer stabilized a-Se x-ray photoconductors were developed for commercial applications. We highlight the unique nature of avalanche multiplication in a-Se and how it has led to the development of the commercial HARP video-tube. An all solid state version of the HARP has been recently demonstrated with excellent avalanche gains; the latter is expected to lead to a number of novel imaging device applications that would be quantum noise limited. While passive pixel sensors use one TFT (thin film transistor) as a switch at the pixel, active pixel sensors (APSs) have two or more transistors and provide gain at the pixel level. The advantages of APS based x-ray imagers are also discussed with examples.<\/jats:p>","DOI":"10.3390\/s110505112","type":"journal-article","created":{"date-parts":[[2011,5,9]],"date-time":"2011-05-09T14:36:58Z","timestamp":1304951818000},"page":"5112-5157","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":486,"title":["Amorphous and Polycrystalline Photoconductors for Direct Conversion Flat Panel X-Ray Image Sensors"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2392-3954","authenticated-orcid":false,"given":"Safa","family":"Kasap","sequence":"first","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK, S7N 5A9, Canada"}]},{"given":"Joel B.","family":"Frey","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK, S7N 5A9, Canada"}]},{"given":"George","family":"Belev","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK, S7N 5A9, Canada"}]},{"given":"Olivier","family":"Tousignant","sequence":"additional","affiliation":[{"name":"Anrad Corporation, 4950 rue L\u00e9vy, Saint-Laurent, QC, H4R 2P1, Canada"}]},{"given":"Habib","family":"Mani","sequence":"additional","affiliation":[{"name":"Anrad Corporation, 4950 rue L\u00e9vy, Saint-Laurent, QC, H4R 2P1, Canada"}]},{"given":"Jonathan","family":"Greenspan","sequence":"additional","affiliation":[{"name":"Anrad Corporation, 4950 rue L\u00e9vy, Saint-Laurent, QC, H4R 2P1, Canada"}]},{"given":"Luc","family":"Laperriere","sequence":"additional","affiliation":[{"name":"Anrad Corporation, 4950 rue L\u00e9vy, Saint-Laurent, QC, H4R 2P1, Canada"}]},{"given":"Oleksandr","family":"Bubon","sequence":"additional","affiliation":[{"name":"Department of Physics, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada"}]},{"given":"Alla","family":"Reznik","sequence":"additional","affiliation":[{"name":"Department of Physics, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada"},{"name":"Thunder Bay Regional Research Institute, 980 Oliver Road, Thunder Bay, ON, P7B 6V4, Canada"}]},{"given":"Giovanni","family":"DeCrescenzo","sequence":"additional","affiliation":[{"name":"Thunder Bay Regional Research Institute, 980 Oliver Road, Thunder Bay, ON, P7B 6V4, Canada"}]},{"given":"Karim S.","family":"Karim","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada"}]},{"given":"John A.","family":"Rowlands","sequence":"additional","affiliation":[{"name":"Thunder Bay Regional Research Institute, 980 Oliver Road, Thunder Bay, ON, P7B 6V4, Canada"},{"name":"Imaging Research, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada"}]}],"member":"1968","published-online":{"date-parts":[[2011,5,9]]},"reference":[{"key":"ref_1","first-page":"223","article-title":"Flat panel detectors for digital radiography","volume":"1","author":"Beutel","year":"2000","journal-title":"Medical Imaging, Physics and Psychophysics"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"63","DOI":"10.3816\/CBC.2003.n.013","article-title":"Digital mammography: A review of technical development and clinical applications","volume":"4","author":"Shah","year":"2003","journal-title":"Clin. Breast Canc"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1990","DOI":"10.1007\/s00330-004-2446-6","article-title":"Digital detectors for mammography: The technical challenges","volume":"14","author":"Noel","year":"2004","journal-title":"Eur. Radiol"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1093\/rpd\/nch532","article-title":"Status and prospects of digital detector technology for CR and DR","volume":"114","author":"Neitzel","year":"2005","journal-title":"Radiat. Protect. Dosim"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1007\/s00247-006-0208-0","article-title":"Flat-panel detectors: How much better are they?","volume":"36","author":"Seibert","year":"2006","journal-title":"Pediatr. Radiol"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1016\/j.nima.2006.01.123","article-title":"Review of medical imaging with emphasis on X-ray detectors","volume":"563","author":"Hoheisel","year":"2006","journal-title":"Nucl. Instrum. Meth. Phys. Res. A"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2767","DOI":"10.1007\/s00330-007-0651-9","article-title":"Flat-detector computed tomography (FD-CT)","volume":"17","author":"Kalender","year":"2007","journal-title":"Eur. Radiol"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"675","DOI":"10.1148\/rg.273065075","article-title":"Advances in digital radiography: Physical principles and system overview","volume":"7","author":"Korner","year":"2007","journal-title":"Radiographics"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"974","DOI":"10.1016\/j.nima.2007.06.041","article-title":"Recent developments in digital radiography detectors","volume":"580","author":"Yorkston","year":"2007","journal-title":"Nucl. Instrum. Meth. Phys. Res. A"},{"key":"ref_10","first-page":"86","article-title":"On the development of digital radiography detectors: A review","volume":"9","author":"Kim","year":"2008","journal-title":"Int. J. Prec. Eng. Manuf"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"468","DOI":"10.1109\/JPROC.2007.913506","article-title":"Design, performance, and applications of a hybrid X-Ray\/MR system for interventional guidance","volume":"96","author":"Fahrig","year":"2008","journal-title":"Proc. IEEE"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1934","DOI":"10.1007\/s00330-005-2734-9","article-title":"Flat detectors and their clinical applications","volume":"15","author":"Spahn","year":"2005","journal-title":"Eur. Radiol"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"315","DOI":"10.1118\/1.2403967","article-title":"Performance of a high fill factor, indirect detection prototype flat-panel imager for mammography","volume":"34","author":"Antonuk","year":"2007","journal-title":"Med. Phys"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1800","DOI":"10.1109\/TNS.2009.2025041","article-title":"Status of direct conversion detectors for medical imaging with X-rays","volume":"56","author":"Overdick","year":"2009","journal-title":"IEEE Trans. Nucl. Sci"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1794","DOI":"10.1002\/pssb.200982007","article-title":"Amorphous selenium and its alloys from early xeroradiography to high resolution x-ray image detectors and ultrasensitive imaging tubes","volume":"246","author":"Kasap","year":"2009","journal-title":"Phys Status Solidi B Basic Solid State Phys"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"288","DOI":"10.1016\/j.cap.2005.11.001","article-title":"Recent advances in X-ray photoconductors for direct conversion X-ray image detectors","volume":"6","author":"Kasap","year":"2006","journal-title":"Curr. Appl. Phys"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1049\/ip-cds:20020350","article-title":"Direct-conversion flat-panel x-ray image detectors","volume":"149","author":"Kasap","year":"2002","journal-title":"IEEE Proc. Circ. Dev. Syst"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"591","DOI":"10.1109\/JPROC.2002.1002529","article-title":"Direct conversion flat panel X-ray image sensors for digital radiography","volume":"90","author":"Kasap","year":"2002","journal-title":"Proc. IEEE"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1063\/1.881994","article-title":"Amorphous semiconductors usher-in-digital X-ray imaging","volume":"50","author":"Rowlands","year":"1997","journal-title":"Phys. Today"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1889\/1.1985000","article-title":"The birth and early childhood of active matrix\u2014A personal memoir","volume":"4","author":"Brody","year":"1996","journal-title":"The J Soc Inform Display"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"250","DOI":"10.1117\/12.208343","article-title":"Digital radiology using self-scanned readout of amorphous selenium: Design considerations for mammography","volume":"2432","author":"Zhao","year":"1995","journal-title":"Proc. SPIE"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1595","DOI":"10.1118\/1.597628","article-title":"X-ray imaging using amorphous selenium: Feasibility of a flat panel self-scanned detector for digital radiology","volume":"22","author":"Zhao","year":"1995","journal-title":"Med. Phys"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"753","DOI":"10.1148\/radiographics.17.3.9153709","article-title":"Flat panel digital radiology with amorphous selenium and active matrix readout","volume":"17","author":"Rowlands","year":"1997","journal-title":"RadioGraphics"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1088\/0031-9155\/42\/1\/001","article-title":"X-ray detectors for digital radiology","volume":"42","author":"Yaffe","year":"1997","journal-title":"Phys. Med. Biol"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1834","DOI":"10.1118\/1.598098","article-title":"Digital radiology using active matrix readout of amorphous selenium: Construction and evaluation of a prototype real-time detector","volume":"24","author":"Zhao","year":"1997","journal-title":"Med. Phys"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1117\/12.208342","article-title":"New digital detector for projection radiography","volume":"2432","author":"Lee","year":"1995","journal-title":"Proc. SPIE"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"511","DOI":"10.1117\/12.237813","article-title":"Discussion on resolution and dynamic range of Se-TFT direct digital radiographic detector","volume":"2708","author":"Lee","year":"1996","journal-title":"Proc. SPIE"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1819","DOI":"10.1118\/1.598097","article-title":"Digital radiology using active matrix readout of amorphous selenium: Theoretical evaluation of detective quantum efficiency","volume":"24","author":"Zhao","year":"1997","journal-title":"Med. Phys"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"539","DOI":"10.1118\/1.598229","article-title":"Digital radiology using active matrix readout of amorphous selenium: Detectors with self-protection against high voltage damage","volume":"25","author":"Zhao","year":"1998","journal-title":"Med. Phys"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"2039","DOI":"10.1118\/1.1405845","article-title":"Effects of characteristic x-rays on the noise power spectra and detective quantum efficiency of photoconductive x-ray detectors","volume":"28","author":"Zhao","year":"2001","journal-title":"Med. Phys"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"735","DOI":"10.1016\/S0026-2714(02)00024-0","article-title":"Amorphous silicon technology for large area digital X-ray and optical imaging","volume":"42","author":"Nathan","year":"2002","journal-title":"Microelectron. Reliab"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"3322","DOI":"10.1118\/1.3049602","article-title":"An investigation of signal performance enhancements achieved through innovative pixel design across several generations of indirect detection, active matrix, flat-panel arrays","volume":"36","author":"Antonuk","year":"2009","journal-title":"Med. Phys"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"250","DOI":"10.1049\/ip-cds:20030555","article-title":"New materials and processes for flat panel X-ray detectors","volume":"150","author":"Street","year":"2003","journal-title":"IEEE Proc. Circ. Dev. Syst"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"3340","DOI":"10.1118\/1.3116364","article-title":"Active pixel imagers incorporating pixel-level amplifiers based on polycrystalline-silicon thin-film transistors","volume":"36","author":"Antonuk","year":"2009","journal-title":"Med. Phys"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"200","DOI":"10.1109\/TED.2002.806968","article-title":"Amorphous silicon active pixel sensor readout circuit for digital imaging","volume":"50","author":"Karim","year":"2003","journal-title":"IEEE Trans. Electron Dev"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"850","DOI":"10.1116\/1.2192526","article-title":"High dynamic range active pixel sensor arrays for digital x-ray imaging using a-Si:H","volume":"24","author":"Lai","year":"2006","journal-title":"J. Vac. Sci. Tech. A Vac. Surf. Films"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1010","DOI":"10.1116\/1.1722219","article-title":"Noise performance of a current-mediated amplified pixel for large-area medical imaging","volume":"22","author":"Karim","year":"2009","journal-title":"J. Vac. Sci. Tech. A Vac. Surf. Films"},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Michell, MJ (2010). Breast Cancer, Cambridge University Press. Chapter 4, Table 4.1.","DOI":"10.1017\/CBO9780511676314"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1636","DOI":"10.1118\/1.598344","article-title":"Digital radiology using active matrix readout of amorphous selenium: Geometrical and effective fill factors","volume":"25","author":"Pang","year":"1998","journal-title":"Med. Phys"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"672","DOI":"10.1118\/1.598572","article-title":"Digital radiology using active matrix readout: amplified pixels for fluoroscopy","volume":"26","author":"Matsuura","year":"1999","journal-title":"Med. Phys"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"2121","DOI":"10.1118\/1.1405844","article-title":"Investigation of a direct conversion flat panel imager for portal imaging","volume":"28","author":"Pang","year":"2001","journal-title":"Med. Phys"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"2274","DOI":"10.1118\/1.1507779","article-title":"Development of high quantum efficiency flat panel detectors for portal imaging: intrinsic spatial resolution","volume":"29","author":"Pang","year":"2002","journal-title":"Med. Phys"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"254","DOI":"10.1118\/1.1538233","article-title":"Imaging performance of amorphous selenium based flat panel detectors for mammography: Characterization of small area prototype detector","volume":"30","author":"Zhao","year":"2003","journal-title":"Med. Phys"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1166","DOI":"10.1118\/1.1707755","article-title":"Evaluation of the imaging properties of an amorphous selenium-based flat panel detector for digital fluoroscopy","volume":"31","author":"Hunt","year":"2004","journal-title":"Med. Phys"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1016\/j.nima.2005.04.053","article-title":"Amorphous selenium flat panel detectors for medical applications","volume":"549","author":"Zhao","year":"2005","journal-title":"Nucl. Instrum. Meth. Phys. Res. A"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"114","DOI":"10.1016\/j.nima.2010.09.006","article-title":"Influence of multi-depositions on the final properties of thermally evaporated TlBr films","volume":"624","author":"Destefano","year":"2010","journal-title":"Nucl. Instrum. Meth. Phys. Res. A"},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Bennett, PR, Shah, KS, Cirignano, LJ, Klugerman, MB, Moy, LP, and Squillante, MR (1999). Characterization of polycrystalline TlBr films for radiographic detectors. IEEE Trans Nucl Sci, 46:689\u2013693.","DOI":"10.1109\/23.775525"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"041801","DOI":"10.1143\/JJAP.49.041801","article-title":"Investigation of PbI2 film fabricated by a new sedimentation method as an x-ray conversion material","volume":"49","author":"Yun","year":"2010","journal-title":"Jpn. J. Appl. Phys"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"140","DOI":"10.1016\/S0168-9002(00)00857-3","article-title":"X-ray imaging with PbI2-based a-Si:H flat panel detectors","volume":"458","author":"Shah","year":"2001","journal-title":"Nucl. Instrum. Meth. Phys. Res. A"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"2738","DOI":"10.1118\/1.3416924","article-title":"Performance evaluation of polycrystalline HgI2 photoconductors for radiation therapy imaging","volume":"37","author":"Zhao","year":"2010","journal-title":"Med. Phys"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"1325","DOI":"10.1088\/0031-9155\/53\/5\/011","article-title":"Investigation of the signal behavior at diagnostic energies of prototype, direct detection, active matrix, flat-panel imagers incorporating polycrystalline HgI2","volume":"53","author":"Du","year":"2010","journal-title":"Phys. Med. Biol"},{"key":"ref_52","doi-asserted-by":"crossref","unstructured":"Zentai, G, Partain, L, and Pavlyuchkova, R (2007). Dark current and DQE improvements of mercuric iodide medical imagers. Proc SPIE, 6510.","DOI":"10.1117\/12.713848"},{"key":"ref_53","doi-asserted-by":"crossref","unstructured":"Kim, K, Kang, S, Park, J, Cho, S, Cha, B, Shin, J, Nam, S, and Kim, J (2007). Quantitative evaluation of mercuric iodide thick film for x-ray imaging device. Proc SPIE, 6142.","DOI":"10.1117\/12.653002"},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"991","DOI":"10.1109\/TNS.2003.814544","article-title":"Near single-crystal electrical properties of polycrystalline HgI2 produced by physical vapor deposition","volume":"50","author":"Zuck","year":"2003","journal-title":"IEEE Trans. Nucl. Sci"},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"160","DOI":"10.1109\/TNS.2002.998745","article-title":"HgI2 polycrystalline films for digital X-ray imagers","volume":"49","author":"Iwanczyk","year":"2002","journal-title":"IEEE Trans. Nucl. Sci"},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"3345","DOI":"10.1063\/1.1436298","article-title":"Comparison of PbI2 and HgI2 for direct detection active matrix x-ray image sensors","volume":"91","author":"Street","year":"2002","journal-title":"J. Appl. Phys"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"861","DOI":"10.1117\/12.479938","article-title":"Improvement of temporal response and output uniformity of polycrystalline CdZnTe films for high-sensitivity x-ray imaging","volume":"5030","author":"Tokuda","year":"2003","journal-title":"Proc. SPIE"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1023\/A:1026297416093","article-title":"Preparation and characterization of polycrystalline CdZnTe films for large-area, high-sensitivity X-ray detectors","volume":"5","author":"Tokuda","year":"2004","journal-title":"J. Mater. Sci. Mater. Electron"},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"188","DOI":"10.1117\/12.533010","article-title":"PbO as direct conversion x-ray detector material","volume":"5368","author":"Simon","year":"2004","journal-title":"Proc. SPIE"},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"2035","DOI":"10.1109\/TNS.2005.856790","article-title":"Analysis of lead oxide (PbO) layers for direct conversion X-ray detection","volume":"52","author":"Simon","year":"2005","journal-title":"IEEE Trans. Nucl. Sci"},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"1978","DOI":"10.1118\/1.2903425","article-title":"Imaging performance of an amorphous selenium digital mammography detector in a breast tomosynthesis system","volume":"35","author":"Zhao","year":"2008","journal-title":"Med. Phys"},{"key":"ref_62","unstructured":"Bogdanovich, S, Cheung, L, Jing, Z, and Parikh, S (2006). Amorphous Selenium Flat Panel x-Ray Imager for Tomosynthesis and Static Imaging, U.S. Patent 7,304,308,."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"207","DOI":"10.1117\/12.602183","article-title":"Spatial and temporal image characteristics of a real-time large area a-Se x-ray detector","volume":"5745","author":"Tousignant","year":"2005","journal-title":"Proc. SPIE"},{"key":"ref_64","unstructured":"Polischuk, BT, and Jean, A (1999). Multilayer Plate for x-Ray Imaging and Method of Producing Same. U.S. Patent 5880472."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"332","DOI":"10.1016\/j.nima.2003.08.058","article-title":"Recent advances in compound semiconductor radiation detectors","volume":"513","author":"Sellin","year":"2003","journal-title":"Nucl. Instrum. Meth. Phys. Res. A"},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"3491","DOI":"10.3390\/s90503491","article-title":"Progress in the development of CdTe and CdZnTe semiconductor radiation detectors for astrophysical and medical applications","volume":"9","author":"Abbene","year":"2009","journal-title":"Sensors"},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.nima.2006.01.110","article-title":"Thick film compound semiconductors for X-ray imaging applications","volume":"563","author":"Sellin","year":"2006","journal-title":"Nucl. Instrum. Meth. Phys. Res. A"},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"118","DOI":"10.1016\/S0022-0248(01)00832-6","article-title":"Thick films of X-ray polycrystalline mercuric iodide detectors","volume":"225","author":"Schieber","year":"2001","journal-title":"J. Cryst. Growth"},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"2571","DOI":"10.1109\/23.650865","article-title":"Novel mercuric iodide polycrystalline nuclear particles counters","volume":"44","author":"Schieber","year":"1997","journal-title":"IEEE Trans. Nucl. Sci"},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"296","DOI":"10.1117\/12.366594","article-title":"High-flux x-ray response of composite mercuric iodide detectors","volume":"3768","author":"Schieber","year":"1999","journal-title":"Proc. SPIE"},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"2660","DOI":"10.1063\/1.371107","article-title":"Electronic transport in polycrystalline Pbl2 films","volume":"86","author":"Street","year":"1999","journal-title":"J. Appl. Phys"},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"2029","DOI":"10.1063\/1.1656484","article-title":"Bandgap dependence and related features of radiation ionization energies in semiconductors","volume":"39","author":"Klein","year":"1968","journal-title":"J. Appl. Phys"},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"1522","DOI":"10.1103\/PhysRevLett.35.1522","article-title":"Electron-hole pair creation energies in semiconductors","volume":"35","author":"Alig","year":"1975","journal-title":"Phys. Rev. Lett"},{"key":"ref_74","doi-asserted-by":"crossref","first-page":"200","DOI":"10.1088\/0022-3727\/32\/3\/004","article-title":"Charge transport and electron-hole creation energy in stabilized a-Se x-ray photoconductors","volume":"32","author":"Haugen","year":"1999","journal-title":"J. Phys. D Appl. Phys"},{"key":"ref_75","doi-asserted-by":"crossref","first-page":"484","DOI":"10.1016\/j.jnoncrysol.2004.08.070","article-title":"Amorphous selenium as an x-ray photoconductor","volume":"345","author":"Belev","year":"2004","journal-title":"J. Non-Cryst. Solids"},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/S0921-5093(01)01668-9","article-title":"Effect of aging on glass transformation measurements by temperature modulated DSC","volume":"328","author":"Tonchev","year":"2002","journal-title":"Mater. Sci. Eng. A"},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"1145","DOI":"10.1116\/1.3472623","article-title":"Relaxation of the electrical properties of vacuum-deposited a-Se1-xAsx photoconductive films: Charge-carrier lifetimes and drift mobilities","volume":"28","author":"Allen","year":"2010","journal-title":"J. Vac. Sci. Technol. A"},{"key":"ref_78","first-page":"1299","article-title":"Advances in physical vapor deposited polycrystalline-HgI2 x-ray imaging detectors","volume":"5","author":"Schieber","year":"2003","journal-title":"J. Optoelectron. Adv. Mater"},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"993","DOI":"10.1016\/S0022-3093(01)01065-1","article-title":"X-ray induced effects in stabilized a-Se x-ray photoconductors","volume":"299","author":"Fogal","year":"2002","journal-title":"J. Non-Cryst. Solids"},{"key":"ref_80","first-page":"239","article-title":"Charge transport in selenium based amorphous xerographic photoreceptors","volume":"26","author":"Kasap","year":"1982","journal-title":"Photograph. Sci. Eng. SPSE"},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"488","DOI":"10.1118\/1.1843353","article-title":"Ghosting caused by bulk charge trapping in direct conversion flat-panel detectors using amorphous selenium","volume":"32","author":"Zhao","year":"2005","journal-title":"Med. Phy"},{"key":"ref_82","doi-asserted-by":"crossref","first-page":"393","DOI":"10.1016\/j.cap.2005.11.026","article-title":"Sensitivity of stabilized a-Se based X-ray photoconductors","volume":"6","author":"Kabir","year":"2006","journal-title":"Curr. Appl. Phys"},{"key":"ref_83","doi-asserted-by":"crossref","first-page":"015102","DOI":"10.1088\/0022-3727\/44\/1\/015102","article-title":"Electrical properties of grain boundaries in polycrystalline materials under intrinsic or low doping","volume":"44","author":"Chowdhury","year":"2011","journal-title":"J. Phys. D Appl. Phys"},{"key":"ref_84","doi-asserted-by":"crossref","first-page":"156","DOI":"10.1103\/PhysRevLett.75.156","article-title":"Charge transport in arrays of semiconductor gamma-ray detectors","volume":"75","author":"Barrett","year":"1995","journal-title":"Phys. Rev. Lett"},{"key":"ref_85","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1063\/1.369425","article-title":"Statistical modeling of charge collection in semiconductor gamma-ray spectrometers","volume":"85","author":"Nemirovsky","year":"2000","journal-title":"J. Appl. Phys"},{"key":"ref_86","doi-asserted-by":"crossref","first-page":"2853","DOI":"10.1088\/0022-3727\/33\/21\/326","article-title":"X-ray sensitivity of photoconductors: Application to stabilized a-Se","volume":"33","author":"Kasap","year":"2000","journal-title":"J. Phys. D Appl. Phys"},{"key":"ref_87","doi-asserted-by":"crossref","first-page":"1664","DOI":"10.1063\/1.1454213","article-title":"Charge collection and absorption-limited sensitivity of x-ray photconductors: Applications to a-Se and HgI2","volume":"80","author":"Kabir","year":"2002","journal-title":"Appl. Phys. Lett"},{"key":"ref_88","first-page":"1","article-title":"Analytical model for incomplete signal generation in semiconductor detectors","volume":"88","author":"Kim","year":"2006","journal-title":"J. Appl. Phys"},{"key":"ref_89","doi-asserted-by":"crossref","first-page":"250","DOI":"10.1016\/S0168-9002(01)00223-6","article-title":"Review of the Shockley-Ramo theorem and its application in semiconductor gamma-ray detectors","volume":"463","author":"He","year":"2001","journal-title":"Nucl. Instrum. Meth. Phys. Res. A"},{"key":"ref_90","doi-asserted-by":"crossref","first-page":"976","DOI":"10.1118\/1.1477235","article-title":"Direct conversion detectors: The effect of incomplete charge collection on detective quantum efficiency","volume":"29","author":"Mainprize","year":"2002","journal-title":"Med. Phys"},{"key":"ref_91","doi-asserted-by":"crossref","first-page":"2735","DOI":"10.1088\/0022-3727\/35\/21\/308","article-title":"DQE of photoconductive x-ray image detectors: Application to a-Se","volume":"35","author":"Kabir","year":"2002","journal-title":"J. Phys. D Appl. Phys"},{"key":"ref_92","doi-asserted-by":"crossref","first-page":"1339","DOI":"10.1118\/1.3326947","article-title":"Effect of repeated x-ray exposure on the resolution of amorphous selenium based x-ray imagers","volume":"37","author":"Kabir","year":"2010","journal-title":"Med. Phys"},{"key":"ref_93","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1063\/1.1852071","article-title":"Analytic model for the spatial and spectral resolution of pixellated semiconducting detectors of high-energy photons","volume":"97","author":"Kozorezov","year":"2005","journal-title":"J. Appl. Phys"},{"key":"ref_94","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1016\/j.nima.2005.03.026","article-title":"Resolution degradation of semiconductor detectors due to carrier trapping","volume":"546","author":"Kozorezov","year":"2005","journal-title":"Nucl. Instrum. Meth. Phys. Res. A"},{"key":"ref_95","doi-asserted-by":"crossref","first-page":"124501","DOI":"10.1063\/1.2206096","article-title":"The effects of large signals on charge collection in radiation detectors: Application to amorphous selenium detectors","volume":"99","author":"Kabir","year":"2006","journal-title":"J. Appl. Phys"},{"key":"ref_96","doi-asserted-by":"crossref","first-page":"975","DOI":"10.1116\/1.1647588","article-title":"Charge collection and absorption-limited x-ray sensitivity of pixellated x-ray detectors","volume":"22","author":"Kabir","year":"2004","journal-title":"J. Vac. Sci. Tech. A"},{"key":"ref_97","doi-asserted-by":"crossref","first-page":"258","DOI":"10.1049\/ip-cds:20030663","article-title":"Direct conversion x-ray sensors: Sensitivity, DQE and MTF","volume":"150","author":"Kabir","year":"2003","journal-title":"IEEE Proc. G Circ. Device. Syst"},{"key":"ref_98","doi-asserted-by":"crossref","first-page":"235106","DOI":"10.1088\/0022-3727\/41\/23\/235106","article-title":"Time and exposure dependent x-ray sensitivity in multilayer amorphous selenium detectors","volume":"41","author":"Manouchehri","year":"2008","journal-title":"J. Phys. D Appl. Phys"},{"key":"ref_99","doi-asserted-by":"crossref","first-page":"895","DOI":"10.1364\/JOSAA.4.000895","article-title":"Detective quantum efficiency of imaging systems with amplifying and scattering mechanisms","volume":"4","author":"Rabbani","year":"1987","journal-title":"J. Opt. Soc. Amer. A"},{"key":"ref_100","unstructured":"Beutel, J, Kundel, HL, and van Metter, RL (2000). Handbook of Medical Imaging, SPIE."},{"key":"ref_101","doi-asserted-by":"crossref","first-page":"074507","DOI":"10.1063\/1.2990765","article-title":"Effects of charge carrier trapping on polycrystalline PbO x-ray imaging detectors","volume":"104","author":"Kabir","year":"2008","journal-title":"J. Appl. Phys"},{"key":"ref_102","doi-asserted-by":"crossref","first-page":"199","DOI":"10.1080\/00223638.1963.11736919","article-title":"The equivalent quantum efficiency of the photographic process","volume":"11","author":"Shaw","year":"1963","journal-title":"J. Photogr. Sci"},{"key":"ref_103","doi-asserted-by":"crossref","first-page":"2352","DOI":"10.1088\/0022-3727\/36\/19\/006","article-title":"Modulation transfer function of photoconductive x-ray image detectors: effects of charge carrier trapping","volume":"36","author":"Kabir","year":"2003","journal-title":"J. Phys. D Appl. Phys"},{"key":"ref_104","doi-asserted-by":"crossref","first-page":"30","DOI":"10.1117\/12.465579","article-title":"Large-area deposition of a polycrystalline CdZnTe film and its applicability to x-ray panel detectors with superior sensitivity","volume":"4682","author":"Tokuda","year":"2002","journal-title":"Proc. SPIE"},{"key":"ref_105","doi-asserted-by":"crossref","first-page":"2767","DOI":"10.1118\/1.1523932","article-title":"A CdZnTe slot-scanned detector for digital mammography","volume":"29","author":"Mainprize","year":"2002","journal-title":"Med. Phys"},{"key":"ref_106","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1557\/PROC-487-129","article-title":"CdTe and CdZnTe room-temperature X-ray and gamma ray detectors and imaging systems","volume":"487","author":"Eisen","year":"1997","journal-title":"Mater. Res. Soc. Symp. P"},{"key":"ref_107","doi-asserted-by":"crossref","first-page":"1118","DOI":"10.1109\/TNS.2006.874953","article-title":"Modulation transfer function of a selenium-based digital mammography system","volume":"53","author":"Hoheisel","year":"2006","journal-title":"IEEE Trans. Nucl. Sci"},{"key":"ref_108","doi-asserted-by":"crossref","first-page":"2080","DOI":"10.1063\/1.1141421","article-title":"An interrupted field time-of-flight technique in transient photoconductivity measurements","volume":"61","author":"Kasap","year":"1990","journal-title":"Rev. Sci. Instrum"},{"key":"ref_109","doi-asserted-by":"crossref","first-page":"3358","DOI":"10.1118\/1.2757002","article-title":"The dependence of the modulation transfer function on the blocking layer thickness in amorphous selenium x-ray detectors","volume":"34","author":"Hunter","year":"2007","journal-title":"Med. Phys"},{"key":"ref_110","doi-asserted-by":"crossref","first-page":"365","DOI":"10.1118\/1.597471","article-title":"X-Ray imaging using amorphous selenium: Inherent spatial resolution","volume":"22","author":"Que","year":"1995","journal-title":"Med. Phys"},{"key":"ref_111","first-page":"2967","article-title":"Spectral response of pixellated semiconductor x-ray detectors","volume":"5","author":"Nilsson","year":"2005","journal-title":"IEEE Nucl. Sci. Symp. Confer. Rec"},{"key":"ref_112","doi-asserted-by":"crossref","first-page":"3601","DOI":"10.1118\/1.2336507","article-title":"Signal and noise transfer properties of photoelectric interactions in diagnostic x-ray imaging detectors","volume":"33","author":"Hajdok","year":"2006","journal-title":"Med. Phys"},{"key":"ref_113","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1016\/S0168-9002(01)00847-6","article-title":"Calculation of the modulation transfer function for the X-ray imaging detector DIXI using Monte Carlo simulation data","volume":"466","author":"Fransson","year":"2001","journal-title":"Nucl. Instrum. Meth. Phys. Res. A"},{"key":"ref_114","doi-asserted-by":"crossref","first-page":"52","DOI":"10.1016\/j.nima.2004.05.073","article-title":"The effect of carrier diffusion on the characteristics of semiconductor imaging arrays","volume":"531","author":"Kozorezov","year":"2004","journal-title":"Nucl. Instrum. Meth. Phys. Res. A"},{"key":"ref_115","doi-asserted-by":"crossref","unstructured":"Meyer, T, Johanson, R, and Kasap, S (2011). The effect of 1\/f noise in integrating sensors and detectors. IET Proc, in press.","DOI":"10.1049\/iet-cds.2010.0220"},{"key":"ref_116","doi-asserted-by":"crossref","first-page":"033706","DOI":"10.1063\/1.1835560","article-title":"Density of localized electronic sates in a-Se from electron time-of-flight photocurrent measurements","volume":"97","author":"Koughia","year":"2005","journal-title":"J. Appl. Phys"},{"key":"ref_117","first-page":"S98","article-title":"Electronic and thermal properties of Magnesium-doped a-Se films","volume":"6","author":"Dash","year":"2009","journal-title":"Phys. Status Solidi C Curr. Top. Solid State Phys"},{"key":"ref_118","doi-asserted-by":"crossref","first-page":"1616","DOI":"10.1016\/j.jnoncrysol.2005.11.086","article-title":"Reduction of the dark current in stabilized a-Se based X-ray detectors","volume":"352","author":"Belev","year":"2006","journal-title":"J. Non-Cryst. Solid"},{"key":"ref_119","first-page":"1053","article-title":"The influence of the substrate temperature on charge transport in vacuum deposited amorphous selenium films","volume":"11","author":"Belev","year":"2009","journal-title":"J. Optoelectron. Adv. Mater"},{"key":"ref_120","first-page":"66","article-title":"Dark decay of electrostatic surface potential on dielectrics via bulk space charge buildup","volume":"22","author":"Kasap","year":"1988","journal-title":"J. Electrostat"},{"key":"ref_121","doi-asserted-by":"crossref","first-page":"223506","DOI":"10.1063\/1.2938888","article-title":"Dark current in multilayer amorphous selenium x-ray imaging detectors","volume":"92","author":"Mahmood","year":"2008","journal-title":"Appl. Phys. Lett"},{"key":"ref_122","doi-asserted-by":"crossref","first-page":"3107","DOI":"10.1109\/TNS.2005.862922","article-title":"Low dark current (0 0 l) mercuric iodide thick films for X-ray direct and digital imagers","volume":"52","author":"Fornaro","year":"2006","journal-title":"IEEE Trans. Nucl. Sci"},{"key":"ref_123","doi-asserted-by":"crossref","first-page":"7393","DOI":"10.1143\/JJAP.47.7393","article-title":"Effect of anealing on the X-ray detection properties of nano-sized polycrystalline lead oxide films","volume":"47","author":"Cho","year":"2008","journal-title":"Jpn. J. Appl. Phys"},{"key":"ref_124","doi-asserted-by":"crossref","unstructured":"Fornaro, L, Sasen, N, P\u00e9rez, M, Noguera, A, and Aguiar, I (2006). Comparison of mercuric bromide and lead bromide layers as photoconductors for direct X-ray imaging applications. IEEE Nucl Sci Symp Confer Rec, 3750\u20133754.","DOI":"10.1109\/NSSMIC.2006.353809"},{"key":"ref_125","doi-asserted-by":"crossref","first-page":"332","DOI":"10.1016\/j.nima.2009.05.184","article-title":"Bismuth tri-iodide polycrystalline films for X-ray direct and digital imagers","volume":"610","author":"Aguiar","year":"2009","journal-title":"Nucl. Instrum. Meth. Phys. Res. A"},{"key":"ref_126","doi-asserted-by":"crossref","first-page":"347","DOI":"10.1109\/JSEN.2009.2034386","article-title":"Digital X-ray imaging using avalanche a-Se photoconductor","volume":"10","author":"Sultana","year":"2010","journal-title":"IEEE Sensors J"},{"key":"ref_127","doi-asserted-by":"crossref","first-page":"2037","DOI":"10.1063\/1.1763986","article-title":"Lucky drift impact ionization in amorphous semiconductors","volume":"96","author":"Kasap","year":"2004","journal-title":"J. Appl. Phys"},{"key":"ref_128","doi-asserted-by":"crossref","first-page":"053711","DOI":"10.1063\/1.2776223","article-title":"Avalanche multiplication phenomenon in amorphous semiconductors: Amorphous selenium versus hydrogenated amorphous silicon","volume":"102","author":"Reznik","year":"2007","journal-title":"J. Appl. Phys"},{"key":"ref_129","doi-asserted-by":"crossref","first-page":"S221","DOI":"10.1007\/s10854-007-9549-1","article-title":"Lucky-drift model for impact ionization in amorphous Semiconductors","volume":"20","author":"Jandieri","year":"2009","journal-title":"J. Mater. Sci. Mater. Electron"},{"key":"ref_130","doi-asserted-by":"crossref","first-page":"387","DOI":"10.1002\/pssa.2210770145","article-title":"Phys. Features of hot carriers in amorphous selenium","volume":"77","author":"Juska","year":"1983","journal-title":"Phys Status Solidi A Appl Mat Sci"},{"key":"ref_131","doi-asserted-by":"crossref","first-page":"790","DOI":"10.1002\/pssc.200777582","article-title":"Photoconductivity in amorphous selenium blocking structures","volume":"5","author":"Reznik","year":"2008","journal-title":"Phys. Status Solidi C Curr. Top. Solid State Phys"},{"key":"ref_132","doi-asserted-by":"crossref","first-page":"2464","DOI":"10.1118\/1.1513157","article-title":"X-ray imaging with amorphous selenium: X-ray to charge conversion gain and avalanche multiplication gain","volume":"29","author":"Hunt","year":"2002","journal-title":"Med. Phys"},{"key":"ref_133","doi-asserted-by":"crossref","first-page":"3183","DOI":"10.1118\/1.2335491","article-title":"X-ray imaging with amorphous selenium: pulse height measurements of avalanche gain fluctuations","volume":"33","author":"Lui","year":"2006","journal-title":"Med. Phys"},{"key":"ref_134","doi-asserted-by":"crossref","first-page":"4654","DOI":"10.1118\/1.2799494","article-title":"X-ray imaging using avalanche multiplication in amorphous selenium: Investigation of intrinsic avalanche noise","volume":"34","author":"Hunt","year":"2007","journal-title":"Med. Phys"},{"key":"ref_135","doi-asserted-by":"crossref","first-page":"976","DOI":"10.1118\/1.2437097","article-title":"X-ray imaging using avalanche multiplication in amorphous selenium: investigation of depth dependent avalanche noise","volume":"34","author":"Hunt","year":"2007","journal-title":"Med. Phys"},{"key":"ref_136","doi-asserted-by":"crossref","first-page":"1039","DOI":"10.1118\/1.2839279","article-title":"Digital radiography using amorphous selenium: Photoconductively activated switch (PAS) readout system","volume":"35","author":"Reznik","year":"2008","journal-title":"Med. Phys"},{"key":"ref_137","first-page":"4982","article-title":"A solid-state amorphous selenium avalanche technology for large area photon counting and photon starved imaging applications","volume":"37","author":"Wronski","year":"2010","journal-title":"Med. Phys. Lett"},{"key":"ref_138","doi-asserted-by":"crossref","first-page":"4324","DOI":"10.1118\/1.2975227","article-title":"Design and feasibility of active matrix flat panel detector using avalanche amorphous selenium for protein crystallography","volume":"35","author":"Sultana","year":"2008","journal-title":"Med. Phys"},{"key":"ref_139","first-page":"S231","article-title":"The effect of K-fluorescence reabsorption of Selenium on the performance of an imaging detector for protein crystallography","volume":"6","author":"Sultana","year":"2009","journal-title":"Phys. Status Solidi C Curr. Top. Solid State Phys"},{"key":"ref_140","doi-asserted-by":"crossref","first-page":"5207","DOI":"10.1118\/1.3002314","article-title":"Direct-conversion flat-panel imager with avalanche gain: Feasibility investigation for HARP-AMFPI","volume":"35","author":"Wronski","year":"2008","journal-title":"Med. Phys"},{"key":"ref_141","doi-asserted-by":"crossref","first-page":"392","DOI":"10.1109\/EDL.1987.26671","article-title":"An avalanche-mode amorphous Selenium photoconductive layer for use as a camera tube target","volume":"8","author":"Tanioka","year":"1987","journal-title":"IEEE Electron Dev. Lett"},{"key":"ref_142","first-page":"S224","article-title":"Temperature dependence of carrier traps in high sensitivity HARP photoconductive film","volume":"6","author":"Ohkawa","year":"2009","journal-title":"Phys. Status Solidi C Curr. Top. Solid State Phys"},{"key":"ref_143","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1109\/11.536588","article-title":"Ultrahigh-sensitivity new Super-HARP camera","volume":"42","author":"Kubota","year":"1996","journal-title":"IEEE Trans Broadcast"},{"key":"ref_144","unstructured":"This work is in preparation and to be published."},{"key":"ref_145","doi-asserted-by":"crossref","first-page":"S6","DOI":"10.1007\/s10854-007-9440-0","article-title":"Applications of avalanche multiplication to flat panel detectors for medical applications","volume":"20","author":"Reznik","year":"2009","journal-title":"J. Mater. Sci. Mater. Electron"},{"key":"ref_146","unstructured":"Cahn, RW, Davis, EA, and Ward, IM (1991). Hydrogenated Amorphous Silicon, Cambridge University Press. Chapter 3,."},{"key":"ref_147","doi-asserted-by":"crossref","first-page":"389","DOI":"10.1002\/pssa.2210590151","article-title":"Impact ionization and mobilities of charge carriers at high electric fields in amorphous selenium","volume":"59","author":"Juska","year":"1980","journal-title":"Phys. Status Solidi A Appl. Mater. Sci"},{"key":"ref_148","doi-asserted-by":"crossref","first-page":"055802","DOI":"10.1088\/0953-8984\/23\/5\/055802","article-title":"Generalized lucky-drift model for impact ionization in semiconductors with disorder","volume":"23","author":"Rubel","year":"2011","journal-title":"J. Phys. Cond. Matt"},{"key":"ref_149","doi-asserted-by":"crossref","first-page":"757","DOI":"10.1557\/PROC-377-757","article-title":"Two dimensional amorphous silicon image sensor arrays","volume":"377","author":"Street","year":"1995","journal-title":"Mater. Res. Soc. Symp. P"},{"key":"ref_150","doi-asserted-by":"crossref","first-page":"469","DOI":"10.1109\/55.954914","article-title":"Readout circuit in active pixel sensors in amorphous silicon technology","volume":"22","author":"Karim","year":"2001","journal-title":"IEEE Electr. Dev. Lett"},{"key":"ref_151","doi-asserted-by":"crossref","first-page":"1891","DOI":"10.1016\/S0026-2714(00)00060-3","article-title":"Low-frequency noise in low temperature unhydrogenated polysilicon thin film transistors","volume":"40","author":"Mercha","year":"2000","journal-title":"Microelectron. Rel"},{"key":"ref_152","doi-asserted-by":"crossref","first-page":"452","DOI":"10.1109\/16.275235","article-title":"CMOS active pixel image sensor","volume":"41","author":"Mendis","year":"1994","journal-title":"IEEE Tran. Electron Dev"},{"key":"ref_153","doi-asserted-by":"crossref","first-page":"846","DOI":"10.1116\/1.2183298","article-title":"High dynamic range pixel architecture for advanced diagnostic medical X-ray imaging applications","volume":"24","author":"Izadi","year":"2006","journal-title":"J. Vac. Sci. Technol. A"},{"key":"ref_154","doi-asserted-by":"crossref","unstructured":"Izadi, MH, Karim, KS, Nathan, A, and Rowlands, JA (2006). Low-noise pixel architecture for advanced diagnostic medical X-ray imaging applications. Proc SPIE, 6142.","DOI":"10.1117\/12.654900"},{"key":"ref_155","doi-asserted-by":"crossref","first-page":"2121","DOI":"10.1109\/TED.2008.926744","article-title":"Two-transistor active pixel sensor readout circuits in amorphous silicon technology for high resolution digital imaging applications","volume":"55","author":"Taghibakhsh","year":"2008","journal-title":"IEEE Trans. Electron Dev"},{"key":"ref_156","doi-asserted-by":"crossref","first-page":"3020","DOI":"10.1109\/TED.2010.2069010","article-title":"An a-Si active pixel sensor (APS) array for medical X-ray imaging","volume":"57","author":"Izadi","year":"2010","journal-title":"IEEE Trans. Electron Dev"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/11\/5\/5112\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T21:56:02Z","timestamp":1760219762000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/11\/5\/5112"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2011,5,9]]},"references-count":156,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2011,5]]}},"alternative-id":["s110505112"],"URL":"https:\/\/doi.org\/10.3390\/s110505112","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2011,5,9]]}}}