• Journal of Sensor Science and Technology
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• v.7 no.1
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• pp.17-22
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• 1998

A HARP (high-gain avalanche rushing amorphous photoconductor) image pickup tube using $4{\mu}m$ thick a-Se photoconductive film was fabricated and its characteristics were investigated. When the target voltage was increased more than 360 V, the signal current increases rapidly but the dark current of the tube was suppressed less than 3.2 nA up to the voltage of 490 V And the quantum efficiency of the target was about 4.3 at the electric field of $1.1{\times}10^{6}V/cm$ and the wavelength of 440 nm. Also the amplitude response of the HARP tube was 7.5% at 800 TV lines, and the decay lag was 3.4%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.108-111
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• 2002

CIGS film has been fabricated on soda-lime glass, which is coated with Mo film. by multi-source evaporation process. The films has been prepared with thickness of 1.0 ${\mu}m$, 1.75${\mu}m$, 2.0${\mu}m$, 2.3${\mu}m$, and 3.0${\mu}m$. X-ray diffraction analysis with film thickness shows that CIGS films exhibit a strong (112) preferred orientation. Furthermore. CIGS films exhibited distinctly decreasing the full width of half-maximum and (112) preferred peak with film thickness. Also, The film's microstructure, such as the preferred orientation, the full width at half-maximum(FWHM), and the interplanar spacing were examined by X-ray diffraction. The preparation condition and the characteristics of the unit layers were as followings ; Mo back contact DC sputter, CIGS absorber layer : three-stage coevaporation, CdS buffer layer : chemical bath deposition, ZnO window layer : RF sputtering, $MgF_2$ antireflectance : E-gun evaporation

• Journal of Oral Medicine and Pain
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• v.31 no.3
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• pp.211-221
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• 2006

Purpose The aims of this study were to evaluate micro-tensile bond strength of composite resin bonded to dentin following high-speed rotary handpiece preparation or Er:YAG laser preparation with two different adhesive systems and to assess the influence of different Er:YAG laser energies on the micro-tensile bond strength. Materials and Methods In this study, 40 third morlars were used. Flat dentin specimans were obtained and randomly assigned to eight groups. Dentin surfaces were prepared with one of four cutting types: carbide bur, Er:YAG laser (2 W, 3 W and 4 W) and conditioned with two bonding systems, Scotchbond Multipurpose Plus (SM), Clearfil SE bond (SE) and composite resin-build ups were created. After storage for 24 hours, each specimen was serially sectioned perpendicular to the bonded surface to produce more than thirty slabs in each group. Micro-tensile bond strength test was performed at a crosshead speed of 1.0 mm/min. Micro-tensile bond strengths (${\mu}TBS$) were expressed as means$\pm$SD. Data were submitted to statistical analysis using two-way ANOVA, one-way ANOVA, Student-Newman-Keuls' multiple comparison test and t-test. Results and Conclusion 1. Regardless of bonding systems, the ${\mu}TBS$ according to cutting types were from highest to lowest : 3 W, 2 W, Bur, and 4 W. In addition, there was no significant difference between Bur and 4 W (p<0.001). 2. Regardless of cutting types, SM showed significantly higher ${\mu}TBS$ than SE (p<0.001). 3. Bonding to dentin conditioned with SM resulted in higher ${\mu}TBS$ for 3 W compared to Bur, 2 W, and 4 W. There was no significant difference between 2 W and Bur (p<0.001). 4. Bonding to dentin conditioned with SE resulted in higher ${\mu}TBS$ for 3 W compared to 2 W, 4 W, and Bur. Bur exhibited significant lower ${\mu}TBS$ than all other cutting types. There were no significant differences between 3 W, 2 W and between 4 W and Bur (p<0.001). 5. The ${\mu}TBS$ of laser cutting groups were shown in order from highest to lowest: 3 W, 2 W and 4 W in two bonding systems. There was no significant difference between 2 W and 3 W in SE (p<0.001). : The ${\mu}TBS$ of composite resin bonded dentin was significantly affected by interaction between the cutting type and bonding system. In the range of 2 W-3 W, cavity preparation of the Er:YAG laser seems to supply good adhesion of composite resin restoration no less than bur preparation. In particular, if you want to use the self-etching system, including Clearfil SE bond for the purpose of a simplification of the bonding procedures and prevention of adverse effects by excessive etching, an Er:YAG laser may offer better adhesion than a bur.

• Journal of the Korean Society of Radiology
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• v.4 no.4
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• pp.37-40
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• 2010

In this paper, transport properties of charge carrier which is produced by x-ray exposure were investigated.. It is the research of charge transport and specific property of trap that is performed in direct digital x-ray image receptor. We measured transit time and drift mobility of charge carriers of a-Se photoconductor using time-of-flight method. We made a testing glass with a-Se of $100{\mu}m$ thickness on corning glass using thermal evaporation method. As a result of this experiment, electron and hole transit time was each $229.17{\mu}s$ and $8.73{\mu}s$ at $10V/{\mu}m$ electric field and drift mobility was each $0.00174cm^2/V{\cdot}s$, $0.04584cm^2/V{\cdot}s$. But the results shows us different measurement value of electron and charge drift mobility and it was investigated about charge transport properties and trap mechanism.

• Journal of the Korean Society of Radiology
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• v.6 no.1
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• pp.73-77
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• 2012

Recently, Interest to the photoconductor, which is used to flat form X-ray detector such as a-Se, $HgI_2$, PbO, CdTe, $PbI_2$ etc. is increasing. In this study, the film layer by using the photoconductive material with particle sedimentation was fabricated and evaluated. The quantization efficiency of the continuous X-ray with the 70 kVp energy bandwidth was analyzed by using the Monte Carlo simulation. With the results, the thickness of film with 64 % quantization efficiency was 180 ${\mu}m$ which is similar to the efficiency of 500 ${\mu}m$ a-Se film. And $HIg_2$ film has the high quantization efficiency of 74 % on 240 ${\mu}m$ thickness. The electrical characteristics of the 239 ${\mu}m$ $Hgl_2$ films produced by particle sedimentation were shown as very low dark current(under 10 $pA/mm^2$), and high sensitivity(19.8 mC/mR-sec) with 1 $V/{\mu}m$ input voltage. The SNR, which is influence to the contrast of X-ray image, was shown highly as 3,125 in low driving voltage on 0.8 $V/{\mu}m$. With the results of this study, the development of the low-cost, high-performance image detector with film could be possible by replacing the film produced by particle sedimentation instead to a-Se detector.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.276-276
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• 2011

진공증착법으로 ITO (indium-tin-oxide) 기판 위에 $AgGaSe_2$ 박막을 성장시켜 그 구조와 광학적 특성을 조사하였다. X-선 회절 분석에 의하여 살창상수는 a=5.97 ${\AA}$와 c=10.88 ${\AA}$이고, 황동광(chalcopyrite) 구조를 하고 있었으며, 그 성장 방향은 (112)방향으로 선택 성장됨을 알 수 있었다. 증착된 박막과 200~400$^{\circ}C$로 열처리한 박막의 실온에서 측정한 광학적인 에너지 띠 간격은 2.02 eV에서 2.28 eV까지 변하였다. 또한 열린회로로 구성되어 있는 시료의 표면에 광 펄스를 주입하여 표면에서 형성된 전하들의 거동을 광유기 방전 특성(PIDC) 방법을 이용하여 조사하였다. 초기전위 V0로 형성된 시료의 양단을 주행하는 운반자 농도, 전류밀도 및 전기장 효과를 관찰하여 운반자의 주행시간, 이동도 그리고 전하운반자 농도를 계산한 결과는 각각 42 ${\mu}s$~81 ${\mu}s$, $1.9{\times}10^{-1}\;cm^2/Vs$~$5.7{\times}10^{-2}\;cm^2/Vs$ 그리고 약 $6.0{\times}10^{17}/cm^3$~$2.0{\times}10^{18}/cm^3$이었으며, p-형 전도를 나타내었다. 원자 힘 현미경 실험으로 제곱평균제곱근 거칠기와 입계크기를 조사하였으며, X-선 광전자 분광실험으로 원소들의 결합상태를 관찰하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.71-74
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• 2003

Photoconductor for direct detection fiat-panel imager present a great materials challenge, since their requirement include high X-ray absorption, ionization and charge collection, low leakage current and large area deposition, CdTe is practical material. We report studies of detector sensitivity, That is an CdTe with $5{\mu}m$ thickness on glass. That is hybrid layer of depositting ZnS:AgCl phosphor with $100{\mu}m$ on CdTe. The leakage current of hybrid is similar to it of a-Se, but photocurrent is larger than a-Se. Both of them have high spatial resolution, but hybrid has higher sensitivity than a-Se at comparable bias voltage.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.2
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• pp.95-102
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• 2004

• Proceedings of the KSEEG Conference
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• 2007.04a
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• pp.105-107
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• 2007

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.817-820
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• 2002

Amorphous selenium based flat panel detectors convert incident x-ray to electric signal directly. Flat panel detectors gain more interest real time medical x-ray imaging. TFT array and electric readout circuits are used in this paper offered by LG.Philips.LCD. Detector is based on a $1536{\times}1280$ array of a-Si TFT pixels. X-ray conversion layer(a-Se) is deposited upper TFT array with a $400{\mu}m$ by thermal deposition technology. Thickness uniformity of this layer is made of thickness control system technology$({\leq}5%)$. Each $139{\mu}m{\times}139{\mu}m$ pixel is made of thin film transistor technology, a storage capacitor and collecting electrode having geometrical fill factor of 86%. This system show dynamic performance. Imaging performance is suited for digital radiography imaging substitute by conventional radiography film system.