• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.139-140
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• 2005

The photocurrent characteristics of CdTe/HgTe/CdTe structured nanoparticles are studied. CdTe/HgTe/CdTe multilayer structured nanoparticles were synthesized by colloidal method. CdTe/HgTe/CdTe multilayer structured nanoparticles were characterized by x-ray diffraction, high-resolution transmission electron microscopy(HRTEM), absorbance and photoluminescence(PL). PL spectrum of CdTe/HgTe/CdTe multilayer structured nanoparticles exhibits a strong exciton bond in the near infrared range. The I-V curves and photoresponses revealed that CdTe/HgTe/CdTe multilayer structured nanoparticles are very prospective materials for the photodetectors.

• Korean Journal of Crystallography
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• v.12 no.3
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• pp.171-176
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• 2001

HgCdTe films were grown on the (100). (111), (211) CdZnTe, and (100) GaAs substrates by metal organic chemical vapor epitaxy. We have investigated the surface morphology, electrical properties, crystalline qualities, and composition of HgCdTe with substrates orientation. Three dimensional facet growth was occurred on (111) CdZnTe substrate. The crystalline quality of HgCdTe on (100) CdZnTe was superior to that of HgCdTe on (100) GaAs. FWHM values of double crystal x-ray diffraction of HgCdTe on (100) CdZnTe and (100) GaAs were 55 and 125arcsec, respectively. HgCdTe on GaAs substrate showed n-type conductivity with high mobility, however, HgCdTe on CdZnTe showed p-type conductivity with carrier concentration of higher than 10/sup 16/㎤.

• Journal of Sensor Science and Technology
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• v.12 no.6
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• pp.282-288
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• 2003

We report the growth of HgCdTe by metal organic vapor phase epitaxy (MOVPE), using (211)B CdTe/Si substrates grown by molecular beam epitaxy (MBE). The surface morphology of these films is very smooth with hillock free. The etch pit densities (EPD) and full widths at half maximum (FWHM) of x-ray rocking curves exhibited that the crystalline quality of HgCdTe epilayer on MBE grown CdTe/Si was improved compare to HgCdTe on GaAs substrate. The Hall parameters of undoped HgCdTe layers on CdTe/Si showed n-type behavior with carrier concentration of $8{\times}10^{14}/cm^3$ at 77K. But HgCdTe on GaAs showed p-type conductivity due to in corporation of p-type impurities during GaAs substrate preparation. It is thought that these results are applicable for large area HgCdTe forcal plane arrays of $1024{\times}1024$ format and beyound.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.122-122
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• 2011

HgCdTe는 고성능 적외선 센서 재료로 널리 사용되고 있다. 현재 상용화된 HgCdTe 소재는 통상적으로 액상 에피 성장법으로 제조 되고 있다. 액상 에피 성장법에 의해 제조된 HgCdTe는 갓 성장 상태에서 많은 양의 Hg-공공(vacancy)을 함유하게 되며 적외선 소자의 응용을 위해서는 이러한 Hg-공공을 채우기 위한 Hg-분위기 열처리 공정을 거치게 된다. 열처리 혹은 성장 공정 시 HgCdTe 소재 내에 발생하는 마이크로 혹은 나노스케일의 조성의 변화는 응력의 집중을 가져오며 이는 전자, 혹은 정공의 응집을 가져와 소자 동작의 불균일성을 야기한다. 본 연구에서는 액상 에피 성장법으로 성장 된 HgCdTe 박막내에 존재하는 응력의 분포와 Hg-공공을 채우기 위한 열처리 과정에서 생성 또는 소멸되는 응력의 변화를 Geometric phase strain 분석법으로 관찰하였다. 분석결과, 응력의 집중된 부분은 주로 성장 시 석출된 Te 및 Hg-공공으로 부터 기인함을 확인하였다. Hg-분위기 열처리를 통하여 석출된 Te 제거 및 Hg-공공의 감소를 확인하였고 이에 따른 응력의 집중 부분도 해소됨을 알 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.56-59
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• 2004

HgTe and HgTe/CdTe core-shell structured nanocrystals(NCs) were synthesized in aqueous solution by colloidal method. HgTe and HgTe/CdTe NCs structure showed very similar XRD patterns because of the same lattice constant and crystal structure of both samples. The absorption and photoluminescence(PL) spectrum of the synthesized HgTe NCs revealed the strong exitonic peak in the IR region. The PL spectrum of HgTe/CdTe NCs have the intense peak in about 700nm shorter than that of HgTe by 400nm. The photocurrent measurement of colloidal NCs are performed using He-Ne laser for light source. The photocurrent of HgTe NCs shows the instant increased current response to light, but HgTe/CdTe NCs revealed a decreased current when lighted to the sample. In the vacuum condition, it shows reverse result that current increased under the illumination of light and it is thought that the molecules like the hydro-oxygen gas in the air give an important effect on the current mechanism.

• Journal of Surface Science and Engineering
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• v.29 no.5
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• pp.325-329
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• 1996

We report on p-type arsenic doping of metalorganic vapor phase epitaxially (MOVPE) grown HgCdTe on (100) GaAs. HgCdTe was grown at $370^{\circ}C$ in a horizontal reactor with using dimethy-cadmium, diisoprophyltelluride, and elemental Hg. We used tris-dimethylaminoarsenic (DMAAs) as the metalorganic for p-doping. 4micron thick CdTe and subsequently 10micron thick HgCdTe were grown on (100) GaAs substrate. Interdiffused multilayer process in which thin CdTe and HgTe layers are grown alternately and interdiffused to obtain homogeneous HgCdTe alloys was used. Arsenic was doped during CdTe growth cycle. After growth HgCdTe was annealed at $415^{\circ}C$ for 15 min and then annealed again at $220^{\circ}C$ for 3 hr, both with Hg-saturate condition. We could obtain p-doping from 2.5$\times$$10^{16}$ to 6.6$\times$$10^{17}$$cm^{-3}$, depending on the DMAAs partial pressure. With the dual Hg-annealing, activation of arsenic was aboutt 90%, which was confirmed by SIMS measurement. With only low temperature annealing at $220^{\circ}C$ for 3hr, activation efficiency was about 50%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.973-976
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• 2004

The results of numerous studies in III-V semiconductors show that sulfur treatment improves the electrical parameters of III-V compound devices. In this article, we examine the effects of sulfidation of HgCdTe surface on the interfacial characteristics of metal-ZnS-HgCdTe structures. Different from sulfidation in III-V material, S can not be act as an impurity because II-S compounds (ZnS, CdS) generally used as passivant for HgCdTe. Our studies of sulfur-treatment on HgCdTe surface show that sulfur agent forms the S- S, II-S bonds at the surface layer. These bonds are very effective to improve the electrical properties of ZnS layer on HgCdTe by reducing the possibility of native oxides formation. After the sulfidation process, MIS capacitors of HgCdTe show great improvement in electrical properties, such as low density of fixed charge and reduced hystereisis width.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1341-1342
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• 2006

Electrical characteristics of field-effect thin film transistors (TFTs) with p-channels of CdTe/CdHgTe core-shell nanocrystals are investigated in this paper. For the fabrication of bottom- and top-gate TFTs, CdTe/CrHgTe nanocrystals synthesized by colloidal method are first dispersed on oxidized p+ Si substrates by spin-coating, the dispersed nanoparticles are sintered at $150^{\circ}C$ to form the channels for the TFTs, and $Al_{2}O_{3}$ layers are deposited on the channels. A representative bottom-gate field-effect TFT with a bottom-gate $SiO_2$ layer exhibits a mobility of $0.21cm^2$/ Vs and an Ion/Ioff ratio of $1.5{\times}10^2$ and a representative top-gate field-effect TFT with a top-gate $Al_{2}O_{3}$ layer provides a field-effect mobility of $0.026cm^2$/ Vs and an Ion/Ioff ratio of $2.5{\times}10^2$. $Al_{2}O_{3}$ was deposited for passivation of CdTe/CdHgTe core-shell nanocrystal layer, resulting in enhanced hole mobility, Ior/Ioff ratio by 0.25, $3{\times}10^3$, respectively. The CdTe/CdHgTe nanocrystal-based TFTs with bottom- and top gate geometries are compared in this paper.

• Journal of Sensor Science and Technology
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• v.13 no.4
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• pp.277-281
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• 2004

$Hg_{1-x}Cd_{x}Te$ (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 $5{\mu}m$ 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 Sensor Science and Technology
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• v.19 no.5
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• pp.398-402
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• 2010

The liquid phase epitaxy(LPE) method was widely used to growth of mercury cadmium telluride(MCT) thin films. However, this method lead to Hg-vacancies in MCT thin film, because Hg has high vapor pressure at this temperature range. This is a well known defect in HgCdTe grown by LPE method. In this study, we report the development of techniques for improving the crystalline quality and controlling the composite uniformity of HgCdTe thin films using high- pressure Hg-ambient annealing method. As a result, we achieved the improvement of the composite uniformity of HgCdTe thin films. It was observed by the high angle annular dark field scanning TEM(HAADF-STEM) analysis. Moreover, new HgTe phase and a shrinking of lattice fringe were observed.