• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.391-394
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• 2002

There has recently been much interest and research in developing digital x-ray systems based on using amorphous selenium(a-Se) photoconductors as the image receptor. The amorphous selenium layer that is currently being studied for use as an x-ray photoconductor is not pure a-Se but rather amorphous selenium alloyed with arsenic. We fabricated samples using the selenium and arsenic alloy with various concentrations of the arsenic. In this work, x-ray photoconductor using amorphous selenium alloyed with arsenic were fabricated with different concentrations of the arsenic (0.1 wt.%, 0.3wt.%, 0.5wt.%, 1wt.%, 1.5wt.%, 3wt.%, 5wt.%). The seven kind of samples was fabricated with a-Se alloyed with arsenic through vacuum thermal evaporation. We also investigate the arsenic concentration dependence on the device performance in radiation detector. The electric characteristics of radiation detector devices with changing additive ratio of the arsenic is performed by measuring the x-ray induced photocurrent and integrating it over time to find the total charge. The thickness of a-Se is $100{\mu}m$. Bias voltages $3V/{\mu}m$, $6V/{\mu}m$， $9V/{\mu}m$ are applied at the samples. As results, the net charge of a-Se 0.3% As sample is $526.0pC/mR/cm^2$ at $9V/{\mu}m$ bias. The net charge is decreased as with the increasing additive ratio of arsenic.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.27-30
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• 2002

Photoconductor for direct detection flat-panel imager present a great materials challenge, since their requirements include high X -ray absorption, ionization and charge collection, low leakage current and large area deposition. Selenium is practical material. But it needs high thickness and high voltage in selenium for high ionization rate. We report comparative studies of detector sensitivity. One is an a-Se with $70{\mu}m$ thickness on glass. The other has hybrid layer of depositting ZnS phosphor with $100{\mu}m$ on a-Se. The leakage current of hybrid is similar to it of a-Se, but photocurrent is lager 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 Graphic Arts Communication Society
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• v.28 no.1
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• pp.65-75
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• 2010

Environmentally friendly, stencil and screen printing for cost-effective for maskless. In this study, UV -LED light source for the dispersion characteristics and high competence photoresist coating was prepared. Wavelength of 365nm UV-LED exposure device using the maskless lithography, 1.7kgf/$cm^2$ $2600mmH_2O$ the injection pressure and the suction pressure by using a dry photoconductor symptoms were dry emulsion on the market as a result, curing properties and adhesion, hardness, solvent resistance and excellent reproduction of fine patterns and ecological stencil technology was available and could be confirmed as a possibility.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.152-152
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• 2003

Hg$\sub$l-x/Cd$\sub$x/Te (MCT) was grown by hot wall epitaxy. Prior to the MCT growth, the CdTe (111) buffer layer was grown on the GaAs substrate at the temperature of 590$^{\circ}C$ for 15 min. When the thickness of the CdTe buffer layer was 5 $\mu\textrm{m}$ or thicker, the full width at half maximum values obtained from the x-ray rocking curves were found to significantly decrease. After a good quality CdTe buffer layer was grown, the MCT epilayers were grown on the CdTe (111) /GaAs substrate at various temperatures in situ. The crystal quality for those epilayers was investigated by means of the x-ray rocking curves and the photocurrent experiment The photoconductor characterization for the epilayers was also measured The energy band gap of MCT was determined from the photocurrent measurement and the x composition rates from the temperature dependence of the energy band gap were turned out

• Journal of the Korean Graphic Arts Communication Society
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• v.12 no.1
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• pp.1.1-11
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• 1994

The photosensitive properties and carrier transport in the organic photoconductor with the carrier transport layers(CTL) of polymer matrix doped with two carrier transport materials above carrier generation layer(CGL) containing oxotitanium phthalocyanine (TiOPc) were investigated. The CGL of TiOPc dispersed in poly(vinylbutyral) was formed as thickness of 0.1${\mu}{\textrm}{m}$and the carrier transport layer was prepared by coating polycarbonate and polyester doped with oxadiazoly(OXD), polyvinylcarbazole (PVK), trinitro fluorenone(TNF) as thickness of 10~15${\mu}{\textrm}{m}$, respectively. We have measured half decay exposure,sensitivity and xerographic gain from the photo-induced discharge curve(PIDC). In this work, it was found that the characteristics of carrier transport were mainly caused by the ionization potential difference of constitutive materials in molecularly doped polymer.

• Journal of the Korean Graphic Arts Communication Society
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• v.15 no.1
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• pp.71-83
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• 1997

In recent years, various kinds of organic photoreceptors have been used for copy machines based on electrophotography. Most of them are constructed into layered devices in which a photogeneration layer is separated from a charge transport layer. They are usually used with application of negative charges. Organic pigment have received considerable attention with phthalocyanine, squaraine, and azo compounds being used to construct zerograpgic photoreceptors with enhanced long wavelength sensitivity, residual potential and zerograpgic gain of squaraine photoconductor were measured from the photoinduced discharge curve. Most of synthesized squaraine derivative couldn`t use for CGM(charge generation material), but it knew that a part of one was able to use it within the possibility. A few appliance is used it know about dependence on CTM(charge transport material) of squaraine derivative. It could know that experiment`s result is 2.5-bis(4-N-N`-diethylaminophenyl)-1,3,4-oxadiazole(OXD) is the bestproduct.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.845-848
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• 2002

The study of photoconductor materials is demanded for development for flat-panel digital x-ray Imager. In this paper, We investigated the feasibility of application as x-ray image sensor using Cd(Zn)Te compound with high stopping power on high radiation. These Cd(Zn)Te samples were fabricated by vacuum thermal evaporation method to large area deposition and investigated I-V measurement as applied voltage. The experimental results show that the additional injection Zn in CdTe film reduced the leakage current, for the $Cd_{0.85}Zn_{0.15}Te$ detector, the net charge had the highest value as $144.58pC/cm^2$ at 30 V.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.4
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• pp.86-100
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• 2008

This article reviews the development of flat-panel detectors for digital radiography based on amorphous materials, Important design parameters and developments are described for the two main components of flat-panel detectors: the X-ray converter and the readout pixel array. This article also introduces the advanced development concepts of new detectors. In addition, the cascaded linear systems method is reviewed because it is a very powerful tool for improving the design and assessment of X-ray imaging detector systems.

• Journal of the Korean Society of Radiology
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• v.3 no.4
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• pp.29-33
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• 2009

Recently, the compound materials(a-Se, $HgI_2$, PbO, CdTe, $PbI_2$, etc.) that are used in flat panel x-ray imager have been studied for digital x-ray imaging. In this paper, the signal detection properties of $HgI_2$ and a-Se conversion layer, are compared. The thick $HgI_2$ film is fabricated by special particle-in-binder method and the conventional vacuum thermal evaporation is used for a deposition of a-Se film. And an electrical characteristic measurements were investigated about leakage current, signal response property and x-ray sensitivity. From the experimental results show that the $HgI_2$ film has a low operation voltage and high signal generation than that of a-Se.

• Journal of the Korean Society of Radiology
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• v.3 no.2
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• pp.11-16
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• 2009

Mercury Iodide as good sensitivity at radiation and has an easy peculiarity that operates at low voltage for other photoconductors(a-Se, a-Si, Ge, etc) Based on this characteristic, we studied about an efficiency of the digital x-ray detector in acccordance with the thickness of photoconductor. To solve the problem that is difficult to make a large area film using PVD(Physical Vapor Deposition)method, we used a PIB(Particle In Binder)method. To make a binder paste, we used a PVB(Polyvinylbutyral) as a binder and a DGME(Diethylene Glycol Monobutyl Ether), DGMEA(Diethylene Glycol Monobutyl Ether Acetate) as a solvent. Using this binder paste, we made a polycrystal mercury iodide film that has an each thickness. To evaluate the electrical properties of this films, we measured a darkcurrent, sensitivity and SNR(Signal to Noise Ratio). Mercury iodide film of the 200um thickness has good electrical properties as a result of the measurement. From this result there is a good chance that replace the existing a-Se(Amnorphous seleinum; a-se) with the mercury iodide.