• 한국전기전자재료학회논문지
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• 제14권8호
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• pp.629-633
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• 2001

Electrical properties of the $\alpha$-In$_2$Se$_3$ single crystals grown by use of the Bridgman technique were examined in the transition temperature range between $\alpha$-phase and $\beta$-phase. $\alpha$-In$_2$Se$_3$ single crystal has ' the rhombohedral structure and lattice constants are a=4.025 $\AA$, c=28.771 $\AA$ in c-axis. The transition temperatures of the stoichiometric $\alpha$-In$_2$Se$_3$ single crystal is 198.8$^{\circ}C$ according to the specimens. The temperature of $\alpha$longrightarrow$\beta$ phase transition decreased but the temperature of $\beta$longrightarrow$\alpha$ phase transition increased as the number of heating-cooling cycle increased.

• 한국정보통신학회논문지
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• 제16권10호
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• pp.2273-2279
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• 2012

동시진공증발법(co-evaporation)으로 Cu(In,Ga)$Se_2$ 박막을 제작하는 논문으로서 1단계($1^{st}$-stage)에서 기판온도(substrate temperature)가 $400^{\circ}C$에서 $In_2Se_3$상($In_2Se_3$ phase)이 존재하였으며 2,3단계($2^{nd}$-stage, $3^{rd}$-stage)에서 기판온도 변화에 따른 흡수 스펙트럼(absorbency spectrum)은 차이가 크지 않다. 이것은 박막의 두께가 전부 $1{\mu}m$ 이상이므로 흡수 스펙트럼(absorbency spectrum)은 거의 차이가 없다. 2,3단계에서 기판온도 변화에 따른 SEM과 XRD를 분석한 결과, 기판온도가 증가할수록 결정구조(crystal structure)의 밀도(density)가 증가하고 기공(vacancy)이 감소하며 $480^{\circ}C$, $500^{\circ}C$에서 Cu(In0.7Ga0.3)$Se_2$상(${\mu}m$)이 형성되었다.

• 한국전기전자재료학회논문지
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• 제26권12호
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• pp.888-893
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• 2013

In this paper, we prepared $Cu(In,Ga)Se_2$ thin films by using co-evaporation method, and analyzed the properties of the thin films. During the thin film preparation process, we confirmed $InGaSe_2$ phase was formed at $400^{\circ}C$ in first stage, and also confirmed the thin films showed the vacancy decrease. In second and third stage, we confirmed the density increase of crystalline structure at over $480^{\circ}C$ and the formation of $Cu(In_{0.7}Ga_{0.3})Se_2$ phase. As the result of SEM and XRD analysis of the films which were before and after heat-treated, we confirmed the disappearance of $Cu_2Se_2$ and the formation of $Cu(In_{0.7}Ga_{0.3})Se_2$ single phase after the heat-treatment, We, therefore, confirmed the heat-treatment did not affect the absorbency spectra of the thin films.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1496-1499
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• 2001

Optical and electrical properties of the $In_2Se_3$ single crystals grown by use of the Bridgman technique were examined in the transition temperature range between $\alpha$-phase and $\beta$-phase. $In_2Se_3$ single crystal has the rhombohedral structure and lattice constants are a=4.025 $\AA$, c=28.771 $\AA$ in C-axis. The transition temperatures of the stoichiometric $In_2Se_3$ single crystal is $10^{-2}{\Omega}cm^{-1}$ according to the specimens. However it varies rapidly in the transition region.

• E2M - 전기 전자와 첨단 소재
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• 제8권3호
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• pp.298-305
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• 1995

Copper-indium diselenide, $CuInSe_2$, thin films have been fabricated by selenizing Cu/In stacked layers with different sputtered Cu/(Cu+ln) mole ratios at 450.deg. C for 1hr on alumina substrates. The selenium source was selenium vapor. Microstructure, crystallization, and composition of the selenized $CuInSe_2$ films were examined by using scanning electron microscope, X-ray diffraction, Auger electron spectroscopy, and secondary ion mass spectrometry. Electrical resistivity and hall effects were also measured to investigate the electrical properties. As the sputtered Cu/(Cu+In) mole ratio of In/Cu layer increased, the amounts of void and CuSe phase in the selenized films increased but the composition of $CuInSe_2$ phase was the same regardless of the sputtered mole ratio. Comparing the electrical properties of $CuInSe_2$ thin film before and after the chemical etching, it was seen that the electrical resistivity, carrier concentration, and carrier mobility of the selenized films were affected by the amount of CuSe phase which seemed to increase primarily the hole concentration of the selenized films.

• 한국진공학회지
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• 제21권3호
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• pp.136-141
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• 2012

열처리 공정으로 제조한 $In_2Se_3$ 박막의 구조 및 광학적 물성을 조사하여 보고한다. 기판위에 스퍼터링 방법으로 인듐(In: indium)을 증착하고 셀레늄 분위기에서 열처리 온도를 변화시키며 In-Se 박막을 제조하였다. 열처리 온도가 증가함에 따라 $In_2Se_3$ 박막의 형성과 상의 변화를 관찰 할 수 있었다. 낮은 열처리 온도(${\leq}150^{\circ}C$)에서는 In의 뭉침 현상을 관찰할 수 있었고 열처리 온도가 $250^{\circ}C$ 부터 $In_2Se_3$ 박막이 형성되며 $350^{\circ}C$ 에서 ${\gamma}-In_2Se_3$ 상이 형성됨을 알 수 있었다. 열처리 온도가 $400^{\circ}C$로 증가면 wurtzite 구조의 고품질 ${\gamma}-In_2Se_3$ 박막을 얻을 수 있었다. 열처리 온도가 증가함에 따라 $In_2Se_3$ 박막의 밴드갭이 증가함을 알 수 있었고, 열처리 온도 $400^{\circ}C$에서 제조된 ${\gamma}-In_2Se_3$ 결정질 박막의 밴드갭이 1.796eV임을 알았다.

• 대한전기학회논문지
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• 제43권2호
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• pp.296-302
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• 1994

Polycrystalline CuInSeS12T thin were prepared by depositing Cu/In layer, which was sequentially sputtered varying the Cu/(Cu+In) mole ratio, on glass substrate and selenizing with selenium metal vapor in a nitrogen atmosphere. Compositional and structural, characterization was carried out by X-ray diffraction (XRD), wavelength-dispersive spectroscopy(WDS), and scanning electron microscope(SEM). Electrical characterization was carried out by the measurements of Hall effect, electrical resistivity. Large indium loss occurs in early stage of the selenization process. The selenized films which had mole ratios larger than 0.28 have chalcopyrite CuInSeS12T phase and these that had less mole ratios have sphalerite phase. The selenized films containing CuS1xTSe phase have Cu-rich CuInSeS12T phase and these that did not contain CuS1xTSe have In-rich CuInSeS12T phase. By optimizing the sputtering conditions,it is possible to fabricate CuInSeS12T thin films which have little secondary phases and an appropriate hole concentration (10S015T ~ 10S016TcmS0-3T) for solar cells.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1991년도 추계학술대회 논문집
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• pp.3-6
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• 1991

CuInSe$_2$ films have been prepared by selenium vapor annealing of sputtered Cu/In layer. The properties of selenized CuInSe$_2$films have been studied as a function of selenization temperature for two sputtered thicknesses. A large indium loss occurs in the sputtered Cu/In layer during the selenization. The indium loss with the selenization temperature is confirmed by the increase in the amount of CuxSe phase at lower temperature and the decrease in the crystallinity of chalocpyrite CuInSe$_2$phase at higher temperature. The variations of the electrical properties in the selenized films with the selenization conditions are due primarily to the variation of hole concentration. The variation of the hole concentration can be explanined by the indium loss away the sputtered Cu/In layer.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권6호
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• pp.297-301
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• 2006

In the present work, we investigate the characteristics of new composition material, chalcogenide $Ge_1Se_1Te_2$ material in order to overcome the problems of conventional PRAM devices. The Tc of $Ge_1Se_1Te_2$ bulk was measured $231.503^{\circ}C$ with DSC analysis. For static DC test mode, at low voltage, two different resistances are observed. depending on the crystalline state of the phase-change resistor. In the first sweep, the as-deposited amorphous $Ge_1Se_1Te_2$ showed very high resistance. However when it reached the threshold voltage(about 11.8 V), the electrical resistance of device was drastically reduced through the formation of an electrically conducting path. The phase transition between the low conductive amorphous state and the high conductive crystal]me state was caused by the set and reset pulses respectively which fed through electrical signal. Set pulse has 4.3 V. 200 ns. then sample resistance is $80\sim100{\Omega}$. Reset pulse has 8.6 V 80 ns, then the sample resistance is $50{\sim}100K{\Omega}$. For such high resistance ratio of $R_{reset}/R_{set}$, we can expect high sensing margin reading the recorded data. We have confirmed that phase change properties of $Ge_1Se_1Te_2$ materials are closely related with the structure through the experiment of self-heating layers.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.59-59
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• 2011

We will report atomically sharp epitaxial growth of $Bi_2Se_3$ three-dimensional topological insulator films on Si(111) substrate with molecular beam epitaxy (MBE). It was achieved by employing two step growth temperatures to prevent any formation of second phase, like as $SiSe_2$ clusters, between $Bi_2Se_3$ and Si substrate at the early stage of growth. The growth rate was determined completely by Bi flux and the Bi:Se flux ratio was kept ~1:15. The second-phase-free atomically sharp interface was verified by RHEED, TEM and XRD. Based on the RHEED analysis, the lattice constant of $Bi_2Se_3$ relaxed to its bulk value during the first quintuple layer implying the absence of strain from the substrate. Single-crystalline XRD peaks of $Bi_2Se_3$ were observed in films as thin as 4 QL. TEM shows full epitaxial structure of $Bi_2Se_3$ film down to the first quintuple layer without any second phases. This growth method was used to grow high quality epitaxial $Bi_2Se_3$ films from 3 QL to 3600 QL. The magneto-transport properties of these thin films show a robust 2D surface state which is thickness independent.