• 한국재료학회지
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• 제7권10호
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• pp.856-862
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• 1997

박막형 CdTe/CdS 태양전지의 배면전극(back contacts)물질로서 Cu도핑된 ZnTe 박막(ZnTe:Cu)을 전착법(electroplating)으로 제조하는 연구를 수행하였다. Sulfate계의 전해질 수용액에서 CdTe 기판과 투명전극으로 코팅된 유리(In$_{2}$O$_{3}$: Sn, ITO)기판 위에 ZnTe 박막을 코팅하는 방법으로써 potentiostat와 기판(cathode), Pt counter electrode, Ag/AgCI 표준전극으로 구성된 장치를 사용하여 pH=2.5-4, T=70-8$0^{\circ}C$, 0.02M $Zn^{2+}$ 1x$10^{-4}$M TeO$_{2}$, 0.2M $K_{2}$SO$_{4}$조건에서 -0.800 Vs~-0.975 V 범위의 전압(V$_{a}$ )에 걸쳐 실험하였다. ITO박막을 기판으로 사용하여 cyclic voltammogram을 작성한 결과 약 -0.50 V 에서 Te환원 peak이 나타났다. Auger electron spectroscopy (AES)로 조성분석한 결과 표면에서 Zn signal이 강하게 나왔고 시편의 두께에 따라 Zn의 signal감소하는 반면 Cd signal은 증가하는 것이 확인되었다. SEM 사진으로부터 ZnTe의 표면이 작은 입자 (0.2$\mu\textrm{m}$ 이하)로 구성되어 있으며 낮은 V$_{a}$ 에서는 입자가 작아지면서 조직이 치밀해짐이 관찰되었다. Optical transmission방법에 의하여 ITO기판위에 입혀진 박막의 밴드갭은 2.5 eV으로 측정되었다. 수용액중의 Cu$_{2+}$와 triethanolamine(TEA)은 산성용액에서 착물형성이 이루어지지 않았으며 1,10-phenanthroline과는 pH=2에서도 착물이 형성되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2006년도 제31회 학술논문발표회 초록집
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• pp.90-90
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• 2006

• 한국결정성장학회지
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• 제10권6호
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• pp.425-433
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• 2000

수평 전기로에서 $CuGaTe_2$다결정을 합성하여 HWE 방법으로 $CuGaTe_2$단결정 박막을 반절연성 GaAs (100) 위에 성장하였다. $CuGaTe_2$단결정 박막은 증발원과 기판의 온도를 각각 $670^{\circ}C$, $410^{\circ}C$로 성장하였다. 이때 단결정 박막의 결정성이 10K에서 측정한 광발광 스펙트럼은 954.5 nm(1.2989 eV) 근처에서 exciton emission 스펙트럼이 가장 강하게 나타났으며, 또한 이중결정 X-선 요동곡선(DCRC)의 반폭치(FWHM)도 139arcsec로 가장 작게 측정되어 최적 성장 조건임을 알 수 있었다. Hall효과는 van der Pauw 방법에 의해 측정되었으며, 온도에 의존하는 운반자 농도와 이동도는 293 K에서 각각 $8.72{\times}10{23}$개 $\textrm m^3$, $3.42{\times}10^{-2}$ $\textrm m^2$/V.s였다. 상온에서 $CuGaTe_2$단결정 박막의 광흡수 특성으로부터 에너지 띠간격이 1.22 eV였다. Bandedge에 해당하는 광전도도 peak의 온도 의존성은 varshni 관계식으로 설명되었으며, varshni 관계식의 상수값은 $E_g$(0) = 1.3982 eV, $\alpha$ = $4.27{\times}10^{-4}$eV/K, $\beta$ = 265.5K로 주어졌다. $CuGaTe_2$단결정 박막의 광전류 단파장대 봉우리들로부터 10K에서 측정된$\Delta$cr(crystal field splitting)은 0.0791 eV, $\Delta$s.o(spin orbit coupling)는 0.2463 eV였다. 10K에서 광발광 봉우리의 919.8nm(1.3479 eV) free exciton($E_x$), 954.5nm(1.2989 eV)는 donor-bound exciton 인 $I_2(D^0,X)$와 959.5nm(1.2921 eV)는 acceptor-bound exciton 인 $I_1(A_0, X)$이고, 964.6nm(1.2853 eV)는 donor-acceptor pair(DAP) 발광, 1341.9nm(0.9239 eV)는 self activated(SA)에 기인하는 광발광 봉우리로 고찰되었다.

• 한국진공학회지
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• 제8권3B호
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• pp.297-301
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• 1999

High quality CdTe single crystal for the solar cell fabrication was grown by vertical Bridgman method. The etch pits patterns of {111} surfaces of CdTe etched by Nakagawa solution was observed the {11} A composed of Cd atoms with typical triangle etch pits of pyramid mode. From the photoluminescence measurement of {111} A, we observed free exciton $(E_x)$ existing only high quality crystal and neutral acceptor bound exciton ($A^{\circ}$, X) having very strong peak intensity. Then, the full width at half maximum and binding energy of neutral acceptor bound exciton were 7 meV and 5.9 meV, respectively. By Haynes rule, and activation energy of impurity was 59meV. Therefore, the origins on impurity level acting as a neutral acceptor were associated Ag or Cu elements.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.273-280
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• 2002

The stochiometric mix of evaporating materials for the CuGaTe$_2$ single crystal thin films was prepared from horizontal furnance. For extrapolation method of X-ray diffraction patterns for the CuGaTe$_2$ polycrystal, it was found tetragonal structure whose lattice constant a$\_$0/ and c$\_$0/ were 6.025 ${\AA}$ and 11.931 ${\AA}$, respectively. To obtain the single crystal thin films, CuGaTe$_2$ mixed crystal was deposited on throughly etched semi-insulator GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were 670 $^{\circ}C$ and 410 $^{\circ}C$ respective1y, and the thickness of the single crystal thin films is 2.1 $\mu\textrm{m}$. The crystalline structure of single crystalthin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). Hall effect on this sample was measured by the method of van der Pauw and studied on carrier density and mobility dependence on temperature. The carrier density and mobility of CuGaTe$_2$ single crystal thin films deduced from Hall data are 8.72${\times}$10$\^$23/㎥, 3.42${\times}$10$\^$-2/㎡/V$.$s at 293K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the CuGaTe$_2$ single crystal thin film, we have found that the values of spin orbit coupling Δs.o and the crystal field splitting Δcr were 0.0791 eV and 0/2463eV at 10K, respectively. From the PL spectra at 10K, the peaks corresponding to free bound excitons and D-A pair and a broad emission band due to SA is identified. The binding energy of the free excitons are determined to be 0.0470eV and the dissipation energy of the donor -bound exciton and acceptor-bound exciton to be 0.0490eV, 0.00558eV, respectively.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.247-256
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• 2024

The glass series modified by tungsten oxide was created using the compounds (75-x) B₂O₃- 10SrCO₃- 8TeO₂- 7ZnO - xWO₃, where x = 0, 1, 5, 10, 22, 27, 34, and 40% mole percentage. A UV-visible spectrophotometer and thermogravimetric-differential thermal analysis (TG-DTA) methods were employed to characterize the specimen's optical and phase transition attributes, respectively. The mass-attenuation coefficient (AC) of all created glasses from BSTZW0 to BSTZ7 was estimated using Geant4 code from 0.05 to 3 MeV and compared to the XCOM software results, with a relative difference of less than 2% between the two results. The increase of WO₃ percentage lead to an increase in the Linear-AC at each studied energy, and this is mainly due to the fact that the higher the percentage of WO₃ in the glass increases its density which causes an increase in the Linear-AC, so an energy of 0.06 MeV, as an example, the values of the Linear-AC was 4.009, 4.509, 5.442, 6812, 8.564, 9.856, 10.999 and 11.628 cm^-1 form BSTZW0 too BSTZW7, respectively. The Half-VL (value layer), Mean-FP (free path), Tenth-VL, and Radiation attenuation performance (RAP) were also calculated for the current BSTZW-glass samples and revealed that BSTZW7 had the best gamma ray attenuation performance at all discussed energies when compared to other studied glass samples.

• 전자공학회논문지D
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• 제34D권10호
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• pp.77-84
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• 1997

The refractive index changes due to the electroptic effect are discussed when external electric fields $E_x, E_y, E_2$ are applied on $LiNbO_3$, a typical anisotropic material. Derived are approximate equations for principal axis' rotations and index changes, results of which are compared with exact results by te computer simulations. In each useful application of $LiNbO_3$substrate, the results of the approximate equations are confirmed to agree with exact solutions.

• Journal of Advanced Marine Engineering and Technology
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• 제29권6호
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• pp.707-712
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• 2005

PRAM (Phase change random access memory) is one of the most promising candidates for next generation Non-volatile Memories. The Phase change materials have been researched in the field of optical data storage media. Among the phase change materials. $Ge_2Sb_2Te_5$ is very well known for its high optical contrast in the state of amorphous and crystalline. However the characteristics required in solid state memory are quite different from optical ones. In this study. the structural Properties of GeSbTe thin films with composition were investigated for PRAM. The 100-nm thick $Ge_2Sb_2Te_5$ and $Sb_2Te_3$ films were deposited on $SiO_2/Si$ substrates by RF sputtering system. In order to characterize the crystal structure and morphology of these films. x-ray diffraction (XRD). atomic force microscopy (AFM), differential scanning calorimetry (DSC) and 4-point measurement analysis were performed. XRD and DSC analysis result of GST thin films indicated that the crystallization of $Se_2Sb_2Te_5$ films start at about $180^{\circ}C$ and $Sb_2Te_3$ films Start at about $125^{\circ}C$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.203-204
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• 2005

PRAM (Phase change Random Access Memory) is one of the most promising candidates for next generation Non-volatile Memories. The Phase change material has been researched in the field of optical data storage media. Among the phase change materials $Ge_2Sb_2Te_5$(GST) is very well known for its high optical contrast in the state of amorphous and crystalline. However, the characteristics required in solid state memory are quite different from optical ones. In this study, the structural properties of GST thin films with composition were investigated for PRAM. The 100-nm thick GeTe and $Sb_2Te_3$ films were deposited on $SiO_2$/Si substrates by RF sputtering system. In order to characterize the crystal structure and morphology of these films, we performed x-ray diffraction (XRD) and atomic force microscopy (AFM).

• 한국광학회지
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• 제17권5호
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• pp.430-436
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• 2006

1550nm 파장대역에서 편광에 관계없이 동작하는 $Ti:LiNbO_3\;2{\times}2$ 삽입/분기 광 멀티플렉서를 구현하였다. 소자는 두 개의 입 출력 광도파로, 두 개의 편광모드분리기, 두 개의 편광모드 변환기 그리고 전기광학효과로 파장을 가변시킬 수 있는 전극으로 구성되었다. TE, TM 편광에 대해서 단일모드 특성을 갖는 채널 광도파로는 x-cut $LiNbO_3$에 Ti 확산 방법으로 제작하였으며, 채널 광도파로 위에 배열된 $SiO_2$ 패드의 전단 스트레인을 이용하여 위상정합 편광모드변환기를 구현하였다. 한편 전기광학효과를 이용하여 파장을 가변시키기 위해서 전압을 인가하여 광도파로의 복 굴절률을 변화시켰다. 0.094nm/V 파장가변률과 최대 17nm 파장을 가변시켰으며, 8.2dB 부 모드레벨과 3.72nm FWHM을 측정하였다.