• 한국결정성장학회지
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• 제15권1호
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• pp.1-9
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• 2005

AgGaS₂ 단결정 박막을 수평 전기로에서 합성한 AgGaS₂ 다결정을 증발원으로하여, hot wall epitaxy(HWE) 방법으로 증발원과 기판(반절연성-GaAs(100))의 온도를 각각 590℃, 440℃로 고정하여 성장하였다. 이때 단결정 박막의 결정성은 광발광 스펙트럼과 이중결정 X-선 요동곡선(DCRC)으로 부터 구하였다. AgGaS₂의 광흡수 스펙트럼으로부터 구한 온도에 의존하는 에너지 밴드갭 E/sub g/(T)는 Varshni 공식에 fitting한 결과 E/sub g/(T) = 2.7284 eV - (8.695×10/sup -4/ eV/K)T²/(T + 332 K)를 잘 만족하였다. 성장된 AgGaS₂ 단결정 박막을 Ag, Ga, S 분위기에서 각각 열처리하여 10K에서 photoluminescience(PL) spectrum을 측정하여 점 결함의 기원을 알아보았다. PL 측정으로 부터 얻어진 V/sub Ag/, V/sub s/, Ag/sub int/, 그리고 S/sub int/는 주개와 받개로 분류되어졌다. AgGaS₂ 단결정 박막을 Ag 분위기에서 열처리하면 n형으로 변환됨을 알 수 있었다. 또한, Ga 분위기에서 열처리하면 열처리 이전의 PL 스펙트럼을 보이고 있어서. AgGaS₂ 단결정 박막에서 Ga은 안정된 결합의 형태로 있기 때문에 자연 결함의 형성에는 관련이 없음을 알았다.

• 한국결정성장학회지
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• 제1권1호
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• pp.26-38
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• 1991

광기능소자로 응용성이 넓은 전기광학결정 $r－6Bi_2O_3{\cdot}SiO_2$(이하 BSO로 약칭)을 EFG(Edge-defined Film-fed Growth)법에 의하여 판상단결정으로 육성하는 기초적 조건을 조사하고 육성된 판단결정의 characterization 및 평가와 물성측정을 하였다. 본 연구에서 얻어진 최적성장조건은 온도구배가 $24^{\circ}C/cm$, 인상속도는 2.0mm/h이었다. 결정성장 최적조건에서 육성된 BSO결정은 제 2상의 석출이 없고 grain boundary가 존재하지 않으며 X선 분석으로도 단결정임이 확인되었다. 육성된 판상단결정의 판면은 (100)면이었고 결정성장 방위는 <100>이었다. 육성된 판상단결정은 편광현미경하에서는 pore, void, inclusion, striation 등의 성장결함이 없는 양질의 단결정이었으나 미세결함인 전위(dislocation)의 존재가 확인되었고 전위밀도는 $5.1{\times}10^5/\textrm{cm}^2$이었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.79-80
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• 2007

To obtain the single crystal thin films, $AgGaSe_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $630^{\circ}C\;and\;420^{\circ}C$, respectively. The temperature dependence of the energy band gap of the $AgGaSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g$(T) = 1.9501 eV - ($8.79{\times}10^{-4}$ eV/K)$T^2$/(T + 250 K). After the as-grown $AgGaSe_2$ single crystal thin films was annealed in Ag-, Se-, and Ga-atmospheres, the origin of point defects of $AgGaSe_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{Ag},\;V_{Se},\;Ag_{int},\;and\;Se_{int}$ obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the Ag-atmosphere converted $AgGaSe_2$ single crystal thin films to an optical p-type. Also, we confirmed that Ga in $AgGaSe_2$/GaAs did not form the native defects because Ga in $AgGaSe_2$ single crystal thin films existed in the form of stable bonds.

• 한국결정학회지
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• 제11권4호
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• pp.212-223
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• 2000

A stochiometric mix of CuInTe₂ polycrystal was prepared in a honizonatal furnace. To obtain the single crystal thin films, CuInTe₂ mixed crystal was deposited on throughly etched GaAs(100) by the HWE system. The source and substrate temperatures were 610℃ and 450℃ respectively, and the thickness of the deposited single crystal thin film was 2.4㎛. CuInTe₂ single crystal thin film was proved to be the optimal growth condition when the excition emission spectrum was the strongest at 1085.3 nm(1.1424 eV) of photoluminescence spectrum at 10 K, and also FWHM of Double Crystal X-ray Rocking Curve (DCRC) was the smallest, 129 arcsec. The Hall effect on this sample was measured by the method of Van der Pauw, and the carrier density and mobility dependent on temperature were 9.57x10/sup 22/ electron/㎥, 1.31x10/sup -2/㎡/V·s at 293 K, respectively. The ΔCr(Crystal field splitting) and the ΔSo (spin orbit coupling splitting( measured at f10K from the photocurrent peaks in the short wavelength of the CuInTe₂ single crystal thin film were about 0.1200 eV, 0.2833 eV respectively. From the PL spectra of CuInTe₂ single crystal thin film at 10 K, the free exciton (E/sub x/) was determined to be 1064.5 nm(1.1647 eV) and the donor-bound exciton(D/sup 0/, X) and acceptor-bound exciton (A/sup 0/, X) were determined to be 1085.3 nm(1.1424 eV) and 1096.8 nm(1.1304 eV0 respectively. And also, the donor-acciptor pair (DAP)P/sub 0/, DAP-replica P₁, DAP-replica P₂ and self-activated (SA) were determined to be 1131 nm (1.0962 eV), 1164 nm(1.0651 eV), 1191.1 nm(1.0340 eV) and 1618.1 nm (0.7662 eV), respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.97-98
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• 2007

A stoichiometric. mixture of evaporating materials for $CuGaSe_2$ single crystal thin films was prepared from horizontal electric furnace. Using extrapolation method of X-ray diffraction patterns for the polycrystal $CuGaSe_2$, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were $5.615\;{\AA}$ and $11.025\;{\AA}$, respectively. To obtain the single crystal thin films, $CuGaSe_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $610^{\circ}C$ and $450^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CuGaSe_2$ single crystal thin films measured with Hall effect by van der Pauw method are $4.87{\times}10^{17}\;cm^{-3}$ and $129\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuGaSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;1.7998\;eV\;-\;(8.7489\;{\times}\;10^{-4}\;eV/K)T^2/(T\;+\;335\;K)$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.223.1-223.1
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• 2013

Since sapphire single crystal is one of the materials that have excellent mechanical and optical properties, the single crystal is widely used in various fields, and the demand for the use of substrate of LED devices is increasing rapidly. However, crystal defects such as dislocations and stacking faults worsen the properties of the single crystal intensely. When sapphire wafer of single crystal is used as LED substrate, especially, crystal defects have a strong influence on the characteristics of a film deposited on the wafer. In such a case quantitative assessment of the defects is essential, and the evaluation technique is now becoming one of the most important factors in commercialization of sapphire wafer. Wet etching is comparatively easy and accurate method to estimate dislocation density of single crystal because etching reaction primarily takes place where dislocations reached crystal surface which are chemically weak points, and produces etch pit. In the present study, the formation behavior of etch pits and etching time dependence were studied systematically. Etch pit density(EPD) analysis using optical microscope was also conducted and measurement uncertainty of EPD was studied to confirm the reliability of the results. EPDs and measurement uncertainties for 4 inch sapphire wafers were analyzed in terms of 5 and 21 points EPD readings. EPDs and measurement uncertainties in terms of 5 points readings for 4 inch wafers were compared by 2 organizations. We found that the average EPD value in terms of 5 points readings for a 4 inch sapphire wafer may represent the EPD value of the wafer.

• 한국결정성장학회지
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• 제32권5호
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• pp.169-174
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• 2022

본 연구는 재생된 SiC 분말을 이용하여 단결정 성장 가능성을 검증하는 것을 목적으로 한다. 재활용 분말의 입도, 형상, 조성, 불순물 등의 기초적인 물성을 분석하고, 이를 활용하여 반응기 내부에서 일어날 수 있는 승화 거동을 예측하였다. 종합적인 판단 결과, 재생 분말의 물성은 단결정 성장에 적합 하였고, 이를 이용하여 단결정 성장 실험을 진행하였다. 높이 25 mm, 직경 100 mm 4H-SiC 단결정 잉곳을 다른 다형혼입 없이 성장 시켰다. 동공 결함 밀도는 0.02 ea/cm², 비저항은 0.015~0.020 ohm·cm² 측정되어 상용 수준의 품질을 얻었으나, 실제 소자 적용을 위해서는 전위 결함, 적층 결함과 관련된 추가 분석이 필요하다고 판단된다.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1997년도 Proceedings of the 12th KACG Technical Meeting and the 4th Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.179-181
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• 1997

When grown the oxide single crystal including Li-ion, optimum oxygen condition is needed. Color and crack are caused in single crystal according too the change in the condition of the oxygen. LiTaO₃ crystals grown from off-composition of congruent melt composition under oxygen deficieny condition didn't generate any crack. LiNbO₃. LiTaO₃ crystals grown from congruent melt composition under optimum oxygen condition caused pale yellow color or colorless with no crack. Color gradually became colorless and generated cracks according to Oxygen excess.

• 한국결정성장학회지
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• 제8권2호
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• pp.211-220
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• 1998

수평 전기로에서 $AgGaS_2$ 다결정을 합성하여 HWE 방법으로 $AgGaS_2$ 단결정 박막을 성장하였다. $AgGaS_2$ 단결정 박막을 성잘할 때 증발원과 기판의 온도를 각각 $590^{\circ}C$, $440^{\circ}C$로 성장하였을 때 이중결정 X-선 요동곡선(double crystal X-ray diffraction rocking curve, DCRC)의 반폭치(FWHM)값이 124 arcsec로 가장 작아 최적 성장조건이었다. 상온에서 $AgGaS_2$ 단결정 박막의 광흡수 특성으로부터 에너지 띠간격이 2.61cV였다. Band edge에 해당하는 광전도도 peak의 온도 의존성은 Varshni 관계식으로 설명되었으며, Vaeshni 관계식의 상수값은 Eg(0) = 2.7284eV, $\alpha$= 8.695$\times$10-4 eV/K, $\beta$= 332K 로 주어졌다. 광발광 봉우리는 20K에서 414.3nm(2.9926eV)와 414.1nm(2.7249eV)는 free exciton(Ex)의 upper polariton과 lower polariton인 {{{{{E}`_{x} ^{u} }}}}와 {{{{{E}`_{x} ^{L} }}}}, 423.6nm(2.9269eV)는 bound exciton emission에 의한 I로 관측되었다. 또한 455nm(2.7249eV)의 peak는 donor-acceptor pair(DAP)에 기인하는 광발광 봉우리로 관측되었다.

• 한국전기전자재료학회논문지
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• 제20권10호
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• pp.829-838
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• 2007

The stochiometric mix of evaporating materials for the $CdGa_2Se_4$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, $CdGa_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $630^{\circ}C$ and $420^{\circ}C$, respectively. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD).The carrier density and mobility of $CdGa_2Se_4$ single crystal thin films measured from Hall effect by van der Pauw method are $8.27{\times}10^{17}\;cm^{-3},\;345\;cm^2/V{\cdot}s$ at 293 K. respectively. The temperature dependence of the energy band gap of the $CdGa_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation, $Eg(T)\;=\;2.6400\;eV\;-\;(7.721{\times}10^{-4}\;eV/K)T^2/(T+399\;K)$. After the as-grown single crystal $CdGa_2Se_4$ thin films were annealed in Cd-, Se-, and Ga -atmospheres, the origin of point defects of single crystal $CdGa_2Se_4$ thin films has been investigated by PL at 10 K. The native defects of $V_{Cd}$, $V_{Se}$, $Cd_{int}$, and $Se_{int}$ obtained by PL measurements were classified as donors or accepters. We concluded that the heat-treatment in the Cd-atmosphere converted single crystal $CdGa_2Se_4$ thin films to an optical p-type. Also, we confirmed that Ga in $CdGa_2Se_4/GaAs$ did not form the native defects because Ga in single crystal $CdGa_2Se_4$ thin films existed in the form of stable bonds.