• Journal of the Korean Ceramic Society
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• v.47 no.2
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• pp.132-135
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• 2010

Thermal properties of layered metal chalcogenides such as $WT_2$ (T=S,Se) with two-dimensionally disordered structure were evaluated. Thermal conductivity shows a marked decrease after exfoliation and subsequent restacking because of random stacking of two-dimensional crystalline sheet, which circumvents thermal conduction pathways along longitudinal direction in anisotropic materials.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3225-3227
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• 2010

The thermal conductivity of layered metal chalcogenides such as $MT_2$ (M = Mo, W; T = S, Se) shows a marked decrease after exfoliation and subsequent restacking process. Random stacking of two-dimensional crystalline sheets circumvents thermal conduction pathways along a longitudinal direction, which results in a reduction in thermal conductivity. $WS_2$ and $WSe_2$ compounds retain p-type conducting behavior after exfoliation and restacking with decreased electrical conductivity due to the change in carrier concentration. $MoSe_2$ compound exhibits metallic behavior < $130^{\circ}C$ with a small Seebeck coefficient, which results from metastable 1T-$MoSe_2$ structure of the restacked phase.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.3
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• pp.388-393
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• 2010

In recent years the research has been focused on the preparation of special glasses, i.e., chalcogenide and heavy metal oxide ones that can transmit optical radiation above 2 um and also other optical parameters exceed those of silica based glasses. The attention in this paper is focused on chalcogenide glasses, on preparation of high quality base glass, for an application in infrared optical product design and manufacture. The amorphous materials of As-Se and Ge-As-Se chalcogenides were prepared by a standard melt-quenching technique. The compositions were mesaured by ICP-AES and EPMA, and structural and thermal properties were studied through various annealing processes. Several anomalies of glass transition and crystallization were observed in the DSC/DTA/TG results of the chalcogenide glass.

• Bulletin of the Korean Chemical Society
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• v.21 no.10
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• pp.989-994
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• 2000

• New & Renewable Energy
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• v.3 no.4
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• pp.54-62
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• 2007

In this paper, we report the research highlight on the preparation and characterization of Indium-free $Cu_2ZnSnSe_4$ and Indium-reduced $CulnZnSe_2$ thin films in order to seek the viability of these absorber materials to be applied in thin film solar cells. The films of $Cu_2ZnSnSe_4\;and\;CulnZnSe_2$ were prepared using mixed binary chalcogenides powders. It was observed that Cu concentration was a function of substrate temperature as well as CuSe mole ratio in the target. Under an optimized condition, $Cu_2ZnSnSe_4\;and\;CulnZnSe_2$ thin films grew with strong [112]. [220/204] and [312/116] reflections. Both $Cu_2ZnSnSe_4\;and\;CulnZnSe_2$ films were found to exhibit a high absorption coefficient of $104^4cm^{-1}\;Cu_2ZnSnSe_4$ film showed a band gap of 1.5eV which closes to the optimum band gap of an ideal solar absorber for a solar cell. On the other side, an increase of optical band gap from 1.0 to 1.25eV was found to be proportional with an increase of Zn concentration in the $CulnZnSe_2$ film. All films in this study revealed a p-type semiconductor characteristic.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.270-273
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• 2007

In this report, Indium-free and Indium-reduced thin film materials for solar absorber were studied in order to search alternative materials for thin film solar cell. The films of $Cu_2ZnSnSe_4$ and $Cu_2ZnSnSe_2$ were deposited using mixed binary chalcogenides powders. From the film bulk analysis result, it is observed that Cu concentration is a function of substrate temperature as well as CuSe mole ratio in the target. Under optimized conditions, $Cu_2ZnSnSe_4$ and $Cu_2ZnSnSe_2$ thin films grow with strong (112), (220/204) and (312/116) reflections. Films are found to exhibit a high absorption coefficient of $10^4$ $cm^{-1}$. $Cu_2ZnSnSe_4$ film shows a 1.5 eV band gap. On the other side, an increasing of optical band gap from 1.0 eV to 1.25 eV ($CuInSnSe_2$) is found to be proportional with an increasing of Zn concentration. All films have a p-type semiconductor characteristic with a carrier concentration in the order of $10^{14}$ $cm^{-3}$, a mobility about $10^1$ $cm^{2{\cdot}-1.}S^{-1}$ and a resistivity at the range of $10^2-10^6$ ${\Omega}{\cdot}m$.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.02a
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• pp.107.1-107.1
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• 2009

• 한국컴퓨터산업교육학회:학술대회논문집
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• 2003.11a
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• pp.75-78
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• 2003

An ideal semiconductor memory technology would combine or unify the attractive features of these technologies without acquiring any of the unattractive features. Such a memory technology, Phase Change RAM is now being developed using the class of elements known as chalcogenides. It is expected that this technology will eventually allow chips that have SRAM speed, DRAM cost, and Flash power characteristics and non-volatility.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.392-395
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• 2015

Metal Mono Chalcogenides(MMC)는 각각의 III족 metal 원자당한개의 chalchogen 원자를 갖고 있는(MX, M=Ga and In, X=S, Se, and Te)층상구조 화합물이다. MMC가 주목받는 가장 큰 이유는 single tetralayer MMC(SL-MMC)라는 2차원 구조를 갖기 때문이다. 2차원 물질은 다양한 물리적 현상을 증명하기 용이하다는 특징을 갖는다. 이 논문에서 우리는 SL-MMC중 Ga-MMC에서 chalchogen 원자가 변화함에 따라 바뀌는 실험 lattice constant를 조사하여 band gap과 formation energy를 Density Function Theory(DFT)로 계산했다.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.400-404
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• 2015

2차원 물질인 metal mono chalcogenides(MMC) 중 GaS와 GaSe를 대상으로 하여 층과 층 사이의 van der Waals(vdW) 상호작용을 density functional theory(DFT) 계산을 이용해 연구하였다. Local density approximation(LDA)와 generalized gradient approximation (GGA)의 두 가지 다른 exchange correlation functional을 이용하고, 또한 두 개의 층 사이에 작용하는 van der Waals 상호작용을 고려한 LDA-D2, GGA-D2 계산을 수행하였다. 이와 같은 네 가지 방법으로 층간거리를 바꾸어 binding energy curve를 계산하였다. 그 결과 GGA-D2계산이 MMC의 층간 상호 작용을 가장 잘 기술하였다.