• Title/Summary/Keyword: amorphous-Selenium

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Transport phenomena of a-Se:As thin film for digital X-ray Conversion Material (디지털 X-선 변환물질을 위한 비소(As) 첨가 비정질 셀레늄(a-Se) 박막의 수송현상)

  • Park, Chang-Hee;Kim, Jae-Hyung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.11a
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    • pp.282-283
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    • 2006
  • The transport phenomena of arsenic (As) doped amorphous selenium(a-Se:As) thin film for digital X-ray conversion material has been reported. The effect of As addition on the carrier mobility and recombination lifetime in a-Se:As sample has been measured using the moving photo-carrier grating (MPG) technique. An Increase in hole mobility and recombination was observed when 0.3% arsenic, was added into a-Se sample, whereas electron mobility decrease with arsenic addition due to the defect density. The fabricated a-Se:03% As device exhibited the highest X-ray sensitivity.

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The effects of As addition on the transport property of a-Se:As films using the moving photo-carrier grating technique

  • Park, Chang-Hee;Lee, Kwang-Sei;Kim, Jeong-Bae;Kim, Jae-Hyung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.11a
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    • pp.252-253
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    • 2005
  • The effects of As addition in amorphous selenium (a-Se) films on the carrier mobilities and the recombination lifetime have been studied using the moving photo-carrier grating (MPG) measurements. The electron and hole mobility, and recombination lifetime of a-Se films with arsenic (As) additions up to 1% have been obtained. We have found an increase in hole drift mobility and recombination lifetime, especially when 0.3% As is added into a-Se film, whereas electron mobility decreases with As addition due to the defect density from shallow traps.

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The electrical and optical properties of Se-As-Te photoconductor and its application (Se-As-Te 광도전막의 특성 및 응용)

  • Park, Sang-Jun;Oh, Sang-Kwang;Choi, Ku-Man;Kim, Ki-Wan
    • Proceedings of the KIEE Conference
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    • 1987.07a
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    • pp.501-504
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    • 1987
  • The photoconductor is made of evaporated amorphous selenium as the base material, doped with arsenic and tellurium to prevent crystallization and to increase the red sensitivity of the amorphous selenium. The four-layered photoconductor of Se-As-Te has good photosensitivity(r=0.9) and high dark resistivity($P_d=10^{12}{\Omega}{\cdot}cm$). therefore, this four-layered photoconductor can be used for the target of color image pick-up tube.

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Transport property of a Se:As films for digital x ray imaging

  • Kim, Jae-Hyung;Nam, Sang-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.04a
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    • pp.85-88
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    • 2006
  • The transport properties of amorphous selenium typical of the material used in direct conversion x-ray imaging devices are reported. The effects of As addition on the carrier mobility and recombination lifetime in amorphous selenium (a-Se) films have been studied using the moving photocarrier grating (MPG) technique. We have found an increase in hole drift mobility and recombination lifetime, especially when 0.3% As is added into a-Se film, whereas electron mobility decreases with As addition due to the defect density. The transport properties for As doped a-Se films obtained by using MPG technique have been compared with the drift mobilities of holes and electrons obtained by time of flight (TOF) measurement.

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Image Quality Evaluation of Digital X-ray Image and Film Image using Contrast Method (Contrast Method를 이용한 디지털 X선 영상과 필름 영상의 영상 질(Quality) 평가)

  • Park, Ji-Koon;Jung, Bong-Jae;Choi, Jang-Yong;Kang, Sang-Sik
    • Journal of radiological science and technology
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    • v.34 no.1
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    • pp.9-15
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    • 2011
  • In this paper, an image quality evaluation of amorphous selenium based x-ray system was performed using modulation transfer function (MTF) measurement. MTF as a main factor of imaging quality evaluation was investigated by contrast method from acquired test pattern image. The MTF value was measured to 36.1% at 3.0 lp/mm which is twice as high as that in the film image. Compared with other studies, the results demonstrate that amorphous selenium based x-ray detector is clinically meaningful.

Development of flat panel digital x-ray detectorusing a-Se (비정질 셀레늄을 이용한 평판 Digital X선 검출기 개발)

  • Park, J.K.;Choi, J.Y.;Kang, S.S.;Cha, B.Y.;Jang, G.W.;Choi, J.Y.;Nam, S.H.
    • Korean Journal of Digital Imaging in Medicine
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    • v.6 no.1
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    • pp.24-30
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    • 2003
  • Flat-panel detector(FPD) is the driving force for realizing the next gene ration of x-ray system. In this study, we developed amorphous selenium(a-Se) based flat-panel digital X-ray detector(DXD) for radiography. The prototype detector consists of an amorphous selenium layer and a thin-film transistor(TFT) array. Comparing to other papers1)-4), optimization of amorphous selenium and progress of evaporation were similar. The pixel pitch of fabricated detector was $139{\mu}m$, fill factor was 86%, and the size was 14"${\times}$8.5". Hand and test bar pattern images were acquired. A high modulation transfer function(MTF) factor was obtained: 58% at 3.0 lp/mm.

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Performance Evaluation of a Selenium(a-Se) Based Prototype Digital Radiation Detector (비정질 셀레늄 기반 디지털 방사선 검출기의 성능 평가)

  • Park, Ji-Koon;Kang, Sang-Sik;Cho, Sung-Ho;Shin, Jung-Wook;Kim, So-Yeong;Son, Dae-Woong;Nam, Sang-Hee
    • Journal of Biomedical Engineering Research
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    • v.28 no.2
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    • pp.300-305
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    • 2007
  • In this study, we have studied the fabrication and the performance evaluation of digital radiation detector of the based on selenium (a-Se) prototype which is widely researched about recently. The detector was fabricated using amorphous selenium in the specification of active area size $7{\times}8.5"$, pixel pitch $139{\mu}m$, and 12 bit ADC. In order for the performance evaluation of the fabricated detector, we used radiation quality RQA 5 that is suggested by the International Electrotechnical Commission (IEC), and evaluated modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). Concerning MTF measurement, we used slit camera (Nuclear Associates, Model : 07-624-2222), and evaluated in the slit method. Also so as to compare the performance evaluation on the detector fabricated in this study, we used Hologic Direct-Ray (DR-1000) and GE Revolution XQ/I system, and evaluated and compared in the same method MTF, NPS, and DQE which are image quality factors. And as a result, the MTF of each detector In Nyquist frequency were evaluated to be 58% (at 3.5 lp/mm) in the case of DR-1000 and 65% (at 2.5 lp/mm) in the case of XQ/I, and that for the detector fabricated in this study was evaluated to be 36% (at 3.51 lp/mm). Also in the case of DQE(0), the detector fabricated in this study, DR-1000 of Hologic company, and XQ/I system of GE company respectively were evaluated as 36%, 32%, and 50%.