• 한국진공학회지
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• 제9권4호
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• pp.353-359
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• 2000

마그네트론 스퍼터링법으로 p형 ($Bi_{0.15}Sb_{0.85})_2Te_3$과 ($Bi_{1-x}Sb_x)_2Te_3$ 열전박막을 제조하여 스퍼터 증착 조건 및 $Sb_2Te_3$ 함량에 따른 열전특성을 분석하였다. Corning glass 기판을 10rpm으로 회전시키며 DC 스퍼터링법으로 $300^{\circ}C$에서 증착한($Bi_{0.15}Sb_{0.85})_2Te_3$ 박막은 $(Bi, Sb)_2Te_3$ 단일상으로 결정화가 완료되고 c축 우선배향성을 나타내었으며, 다른 조건으로 증착한 ($Bi_{0.15}Sb_{0.85})_2Te_3$ 박막보다 높은 185 $\mu$V/K의 Seebeck 계수를 나타내었다. p형(Bi$_{1-x}$ Sb$_{x}$)$_2$Te$_3$ (0.77$\leq$x$\leq$ 1.0) 박막에서는 Sb$_2$Te$_3$ 함량이 증가함에 따라 Seebeck 계수와 전기비저항이 감소하였으며($Bi_{1-x}Sb_x)_2Te_3$조성에서 $0.79\times10^{-3}W/K^2$-m의 최대 출력인자를 나타내었다.

• 한국재료학회지
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• 제21권4호
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• pp.192-195
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• 2011

The electro-deposition of compound semiconductors has been attracting more attention because of its ability to rapidly deposit nanostructured materials and thin films with controlled morphology, dimensions, and crystallinity in a costeffective manner (1). In particular, low band-gap $A_2B_3$-type chalcogenides, such as $Sb_2Te_3$ and $Bi_2Te_3$, have been extensively studied because of their potential applications in thermoelectric power generator and cooler and phase change memory. Thermoelectric $Sb_xTe_y$ films were potentiostatically electrodeposited in aqueous nitric acid electrolyte solutions containing different ratios of $TeO_2$ to $Sb_2O_3$. The stoichiometric $Sb_xTe_y$ films were obtained at an applied voltage of -0.15V vs. SCE using a solution consisting of 2.4 mM $TeO_2$, 0.8 mM $Sb_2O_3$, 33 mM tartaric acid, and 1M $HNO_3$. The stoichiometric $Sb_xTe_y$ films had the rhombohedral structure with a preferred orientation along the [015] direction. The films featured hole concentration and mobility of $5.8{\times}10^{18}/cm^3$ and $54.8\;cm^2/V{\cdot}s$, respectively. More negative applied potential yielded more Sb content in the deposited $Sb_xTe_y$ films. In addition, the hole concentration and mobility decreased with more negative deposition potential and finally showed insulating property, possibly due to more defect formation. The Seebeck coefficient of as-deposited $Sb_2Te_3$ thin film deposited at -0.15V vs. SCE at room temperature was approximately 118 ${\mu}V/K$ at room temperature, which is similar to bulk counterparts.

• 한국진공학회지
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• 제11권1호
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• pp.28-34
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• 2002

진공 증착한 $Sb_{2-x}Bi_xTe_3$ 박막은 Bi 농도에 관계없이 비정질 형태로 성장되었고, XPS 분석 결과 증착 물질과 거의 유사한 조성을 가짐을 알 수 있었다. 또한 박막의 광학적, 전기적 특성을 설명하기 위해 여러 미세구조 파라미터들을 계산하였다. 한편, 박막 내 Bi 농도가 증가함에 따라 전기 비저항은 급격히 감소하였고, 특히 높은 Bi 농도(x=1.0)에서는 전도 특성이 p-type에서 n-type으로 변화되었다. 또한 $Sb_{2-x}Bi_xTe_3$ 박막의 굴절 지수 및 광학적 밴드 갭은 Bi 농도에 따라 증가하였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1997년도 한국재료학회 춘계학술발표회
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• pp.66-66
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• 1997

• 한국전기전자재료학회논문지
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• 제15권3호
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• pp.220-226
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• 2002

Amorphous $Sb_{2-x}Bi_xTe_3$ (x = 0.0, 0.5 and 1.0) thin films were prepared by vacuum evaporation. The resistivity of 7he films decreases from 1.4{\times}10^{-2}$ to $8.84{\times}10^{-5}\Omega cm$ and the type of conductivity changes from p to n with the increase of the x value of the films. D.C. conduction studies on these films ate performed at various electric fields in the temperature range of 303-403 K. At low electric fields, two types of conduction mechanisms, i.e. the variable range hopping and the phonon assisted hopping are found to be responsible for the conduction, depending upon the temperature. The activation energy decreases from 0.082 to 0.076 eV in the temperature range of 303-363 K and from 0.47-0.456 eV in the second range of 363-403 K, indicating the shift of the Fermi level towards the conduction band edge and hence the change of the conduction from P to n type with the increase of the Bi concentration. Poole-Frankel emission dominates at high fields. The shape of the potential well of the localized centre is deduced and the mean free path of the charge carriers is also calculated.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.77-80
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• 1995

GaSb crystals were grown by the vertical Bridgman method. P-type GaSb crystals were grown with Ga:Sb=1:1 at % ratio without dopants and with Te, respectively. Also, GaSb:Te crystals were investigated. Lattice constants were 6.117${\AA}$ for p-type. The carrier concentration, the resistivity, and the carrier mobility measured by the van der Pauw method were p≡8 x $10^{16}$$cm^{-3}$, p≡0.20$\Omega$-cm, ${\mu}$$_{n}$≡$400\textrm{cm}^2$$V^{-1}$$sec^{-1}$ for p-type, n≡1 x $10^{17}$$cm^{-3}$, p≡0.15 $\Omega$-cm, ${\mu}$$_{n}$≡$500\textrm{cm}^2$$V^{-1}$$sec^{-1}$ for n-type at 300K. In case of treating with metal ion of $Ru^{+3}$, $Pt^{+1}$, p≡2 x $10^{17}$$cm^{-3}$, p≡0.08$\Omega$-cm, ${\mu}$$_{n}$≡420$\textrm{cm}^2$$V^{-1}$$sec^{-1}$ for p-type, n≡2.5 x $10^{17}$$cm^{-13}$, p≡0.07 $\Omega$-cm, ${\mu}$$_{n}$≡520$\textrm{cm}^2$$V^{-1}$$sec^{-1}$ for n-type were obtained.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.138-139
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• 2006

Metal organic chemical vapor deposition has been investigated for growth of $Sb_{2-x}Bi_xTe_3$ films on (001) GaAs substrates using diisopropyltelluride, triethylantimony and trimethylbismuth as metal organic sources. The thermoelectric properties were measured at room temperature and include Seebeck coefficient, electrical conductivity and Hall effect. In-plane carrier concentration and electrical Hall mobility were highly dependent on precursor's composition ratio and deposition temperature. The thermoelectric Power factor($={\alpha}^2{\sigma}$) was calculated from theses properties. The best Power factor was $2.6\;{\times}\;10^{-3}W/mK^2$, given by grown $Sb_{1.6}Bi_{0.4}Te_3$ at $450^{\circ}C$. These materials could potentially be incorporated into advanced thermoelectric unicouples for a variety of power generation applications.

• 한국분말재료학회지
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• 제23권2호
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• pp.120-125
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• 2016

P-type ternary $Bi_{0.5}Sb_{1.5}Te_3$ alloys are fabricated via mechanical alloying (MA) and spark plasma sintering (SPS). Different ball sizes are used in the MA process, and their effect on the microstructure; hardness, and thermoelectric properties of the p-type BiSbTe alloys are investigated. The phases of milled powders and bulks are identified using an X-ray diffraction technique. The morphology of milled powders and fracture surface of compacted samples are examined using scanning electron microscopy. The morphology, phase, and grain structures of the samples are not altered by the use of different ball sizes in the MA process. Measurements of the thermoelectric (TE) transport properties including the electrical conductivity, Seebeck coefficient, and power factor are measured at temperatures of 300-400 K for samples treated by SPS. The TE properties do not depend on the ball size used in the MA process.

• 한국전기전자재료학회논문지
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• 제30권3호
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• pp.133-138
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• 2017

We evaluated the structural, electrical and optical properties of tungsten (W)-doped $Ge_8Sb_2Te_{11}$ thin films. In a previous work, GeSbTe alloys were doped with different materials in an attempt to improve thermal stability. 200 mm thick $Ge_8Sb_2Te_{11}$ and W-doped $Ge_8Sb_2Te_{11}$ films were deposited on p-type Si (100) and glass substrates using a magnetron co-sputtering system at room temperature. The fabricated films were annealed in a furnace in the $0{\sim}400^{\circ}C$ temperature range. The structural properties were analyzed using X-ray diffraction (X'pert PRO, Phillips). The results showed increased crystallization temperature ($T_c$) leading to thermal stability in the amorphous state. The optical properties were analyzed using an UV-Vis-IR spectrophotometer (Shimadzu, U-3501, range : 300~3,000 nm). The results showed an increase in the crystalline material optical energy band gap ($E_{op}$) and an increase in the $E_{op}$ difference (${\Delta}E_{op}$). This is a good effect to reduce memory device noise. The electrical properties were analyzed using a 4-point probe (CNT-series). This showed increased sheet resistance ($R_s$), which reduces programming current in the memory device.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.134-134
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• 2009

In this work, we report that crystallization speed as well as the electrical and optical properties about the N-doped $Ge_2Sb_2Te_5$ thin films. The 200-nm-thick N-doped $Ge_2Sb_2Te_5$ thin film was deposited on p-type (100) Si and glass substrate by RF reactive sputtering at room temperature. The amorphous-to-crystalline phase transformation of N-doped $Ge_2Sb_2Te_5$ thin films investigated by X-ray diffraction (XRD). Changes in the optical transmittance of as-deposited and annealed films were measured using a UV-VIS-IR spectrophotometer and four-point probe was used to measure the sheet resistance of N-doped $Ge_2Sb_2Te_5$ thin films annealed at different temperature. In addition, the surface morphology and roughness of the films were observed by Atomic Force Microscope (AFM). The crystalline speed of amorphous N-doped $Ge_2Sb_2Te_5$ films were measured by using nano-pulse scanner with 658 nm laser diode (power : 1~17 mW, pulse duration: 10~460 ns). It was found that the crystalline speed of thin films are decreased by adding N and the crystalline temperature is higher. This means that N-dopant in $Ge_2Sb_2Te_5$ thin film plays a role to suppress amorphous-to-crystalline phase transformation.