• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.164-167
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• 2002

The general dicing process cuts a semiconductor wafer to lengthwise and crosswise direction by using a rotating circular diamond blade. But inferior goods are made under the influence of several parameters in dicing process such as blade, wafer, cutting water and cutting conditions. Moreover we can not applicable this dicing method to GaN wafer, because the GaN wafer is harder than the other wafer such as SiO$_2$, GaAs, CaAsP, and AlCaAs. In order to overcome this problem, development of a new dicing process and determination of dicing parameters are necessary. This paper describes determination of several parameters - scribing depth, scribing force, scriber inclined angle, scribing speed, and factor for scriber replacement - for a new dicing machine using scriber.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.386-391
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• 2003

Sing1e crystal $CuAlSe_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at $410^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuAlSe_2$source at $680^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence(PL) and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $CuAlSe_2$ thin films measured with Hall effect by van der Pauw method are $9.24{\times}10^{16}\;cm^{-3}$ and $295\;cm^2/V{\cdot}\;s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuAlSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;2.8382\;eV\;-\;(8.86\;{\times}\;10^{-4}\;eV/K)T^2/(T\;+\;155K)$. After the as-grown single crystal $CuAlSe_2$ thin films were annealed in Cu-, Se-, and Al-atmospheres, the origin of point defects of single crystal $CuAlSe_2$ 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. And we concluded that the heat-treatment in the Cu-atmosphere converted single crystal $CuAlSe_2$ thin films to an optical n-type. Also, we confirmed that Al in $CuAlSe_2/GaAs$ did not form the native defects because Al in single crystal $CuAlSe_2$ thin films existed in the form of stable bonds.

• 한국전기전자재료학회논문지
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• 제16권10호
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• pp.871-880
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• 2003

Single crystal CuAlSe$_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at 410 C with hot wall epitaxy (HWE) system by evaporating CuAlSe$_2$ source at 680 C. The crystalline structure of the single crystal thin films was investigated by the photoluminescence(PL) and double crystal X -ray diffraction (DCXD). The carrier density and mobility of single crystal CuAlSe$_2$ thin films measured with Hall effect by van der Pauw method are 9.24${\times}$10$\^$16/ cm$\^$-3/ and 295 cm$^2$/V $.$ s at 293 K, respectively. The temperature dependence of the energy band gap of the CuAlSe$_2$ obtained from the absorption spectra was well described by the Varshni's relation, Eg(T) = 2.8382 eV - (8.86 ${\times}$ 10$\^$-4/ eV/K)T$^2$/(T + 155K). After the as-grown single crystal CuAlSe$_2$ thin films were annealed in Cu-, Se-, and Al-atmospheres, the origin of point defects of single crystal CuAlSe$_2$ 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 acceptors. And we concluded that the heat-treatment in the Cu-atmosphere converted single crystal CuAlSe$_2$ thin films to an optical n-type. Also, we confirmed that Al in CuAlSe$_2$/GaAs did not form the native defects because Al in single crystal CuAlSe$_2$ thin films existed in the form of stable bonds.

• Current Photovoltaic Research
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• 제4권3호
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• pp.108-113
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• 2016

III-V compound semiconductor based thin film solar cells promise relatively higher power conversion efficiencies and better device reliability. In general, the thin film III-V solar cells are fabricated by an epitaxial lift-off process, which requires an $Al_xGa_{1-x}As$ ($x{\geq}0.8$) sacrificial layer and an inverted solar cell structure. However, the device performance of the inversely grown solar cell could be degraded due to the different internal diffusion conditions. In this study, InGaP/GaAs double-junction solar cells are inversely grown by MOCVD on GaAs (100) substrates. The thickness of the GaAs base layer is reduced to minimize the thermal budget during the growth. A wide band gap p-AlGaAs/n-InGaP tunnel junction structure is employed to connect the two subcells with minimal electrical loss. The solar cell structures are transferred on to thin metal films formed by Au electroplating. An AlAs layer with a thickness of 20 nm is used as a sacrificial layer, which is removed by a HF:Acetone (1:1) solution during the epitaxial lift-off process. As a result, the flexible InGaP/GaAs solar cell was fabricated successfully with an efficiency of 27.79% under AM1.5G illumination. The efficiency was kept at almost the same value after bending tests of 1,000 cycles with a radius of curvature of 10 mm.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.154.2-154.2
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• 2008

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1333-1334
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• 2007

Al thin film was the most popular electrode in semiconductor and flat panel display world, because of its electrical conductivity, selectivity and easy to apply to thin film. However, Al thin films were not good to use on the bottom electrode about the crystalline growth of inorganic compound materials such as ZnO, AlN and GaN, because of its surface roughness and melting points. In this paper, we investigated Ar plasma surface treatment of Al thin film to enhance the surface roughness and electrical conductivity using the reactive ion etching system. Several process conditions such as RF power, working pressure and process time were controlled. In results, the surface roughness showed $15.53\;{\AA}$ when RF power was 100 W, working pressure was 50 mTorr and process time was 10 min. Also, we tried to deposit ZnO thin films on the each Al thin films, the upper conditions showed the best crystalline characteristics by x-ray diffraction.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.76-77
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• 2005

Single crystal $CuAlSe_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at 410$^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuAlSe_2$ source at $680^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence(PL) and double crystal X-ray diffraction (DCXO). The temperature dependence of the energy band gap of the $CuAlSe_2$ obtained from the absorpt ion spectra was wel1 described by the Varshni's relation, $E_g$(T) = 2.8382 eV - ($8.86\times10^{-4}$ eV/H)$T_2$/(T + 155K). After the as-grown single crystal $CuAlSe_2$ thin films were annealed in Cu-, Se-, and Al-atmospheres, the origin of point defects of single crystal $CuAlSe_2$ 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 acceptors. And we concluded that the heat-treatment in the Cu-atmosphere converted single crystal $CuAlSe_2$ thin films to an optical n-type. Also. we confirmed that hi in $CuAlSe_2$/GaAs did not form the native defects because Al in single crystal $CuAlSe_2$ thin films existed in the form of stable bonds.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.467-468
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• 2006

To perform the comparative study, we experimented on two differential epitaxial structures, the conventional Metamorphic High Electron Mobility Transistor (MHEMT) using the InAlAs/InGaAs structure and the InP-composite channel MHEMT adopting the InAlAs/InGaAs/InP/n-InP structure. Compared to the conventional MHEMT, the InP-composite channel MHEMT shows improved breakdown performance; over about 3.5 V. This increased breakdown voltage can be explained by the lower impact ionization coefficient of the InP-composite channel MHEMT than that of the conventional MHEMT.

• 암석학회지
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• 제13권3호
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• pp.142-151
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• 2004

경기육괴의 남서부지역인 용인-안성지역에는 선캠브리아기 초기의 기반암으로 사료되는 고변성도의 편마암과 편암 그리고 이를 관입한 중생대 쥬라기 화강암류가 광범위하게 분포하고 있다. 이 논문에서는 용인-안성지역에 분포하는 선캠브리아기의 변성암류와 이를 관입한 쥬라기 화강암의 지구화학적 특징을 토대로 서로의 상관성을 토의하고자 하였다. 연구결과에 의하면, 변성암류의 Nd모델연대( $T_{DM}$ $^{Nd}$ )는 경기육괴의 가장 활발한 지각형성시기였던 약 2.6Ca～2.9Ga(Lee or of., 2003) 동안에 생성된 기원물질로부터 유래되었음을 지시 해준다. 그리고 Nd 모델 연대( $T_{DM}$ $^{Nd}$ )에 의하면, 흑운모 호상편마암과 석영장석질 편마암의 Nd 모델 연대는 각각 2.59Ga～2.73Ga, 2.70Ga～2.88Ga로서 석영장석질 편마암의 기원물질이 약간 더 오래된 것으로 나타났다. 따라서 이들 변성암류는 경기육괴의 가장 활발한 지각형성시기의 기원물질로부터 유래되었음을 알 수 있다. 희토류원소의 분포에 있어서, 흑운모 호상편마암은 (La/Yb)$_{N}$ 값이 37～136으로 매우 급격한 기울기를 보여주는 반면에, 앰피볼라이트의 경우 (La/Yb)$_{N}$ 값이 4.65～6.64로 거의 편평한 분포양상을 보여준다 이는 흑운모호상편마암은 분화가 상당히 일어난 기원물질로부터 유래되었음을 지시해준다. 특히 연구지역내 흑운모 호상편마암, 석영장석질 편마암과 같은 고변성도의 변성암류에서 관찰되는 희토류원소의 분포도는 초기기원물질의 특성을 그대로 보유하고 있는 것으로 볼 수 있다 그리고 인접한 중생대 화강암의 (La/Yb)$_{N}$ 과 Nd 모델연대는 각각 32～40, 1.69Ga～2.08Ga로서 기반암인 흑운모 편마암과 석영장석질 편마암과는 지구화학적 특성이 서로 다른 젊은 기원물질로부터 유래되었음을 지시해준다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.287.1-287.1
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• 2016

Three-dimensional (3-D) semiconductor nanoarchitectures, including nano- and micro- rods, pyramids, and disks, are emerging as one of the most promising elements for future optoelectronic devices. Since these 3-D semiconductor nanoarchitectures have many interesting unconventional properties, including the use of large light-emitting surface area and semipolar/nonpolar nano- or micro-facets, numerous studies reported on novel device applications of these 3-D nanoarchitectures. In particular, 3-D nanoarchitecture devices can have noticeably different current spreading characteristics compared with conventional thin film devices, due to their elaborate 3-D geometry. Utilizing this feature in a highly controlled manner, color-tunable light-emitting diodes (LEDs) were demonstrated by controlling the spatial distribution of current density over the multifaceted GaN LEDs. Meanwhile, for the fabrication of high brightness, single color emitting LEDs or laser diodes, uniform and high density of electrical current must be injected into the entire active layers of the nanoarchitecture devices. Here, we report on a new device structure to inject uniform and high density of electrical current through the 3-D semiconductor nanoarchitecture LEDs using metal core inside microtube LEDs. In this work, we report the fabrications and characteristics of metal-cored coaxial $GaN/In_xGa_{1-x}N$ microtube LEDs. For the fabrication of metal-cored microtube LEDs, $GaN/In_xGa_{1-x}N/ZnO$ coaxial microtube LED arrays grown on an n-GaN/c-Al2O3 substrate were lifted-off from the substrate by wet chemical etching of sacrificial ZnO microtubes and $SiO_2$ layer. The chemically lifted-off layer of LEDs were then stamped upside down on another supporting substrates. Subsequently, Ti/Au and indium tin oxide were deposited on the inner shells of microtubes, forming n-type electrodes of the metal-cored LEDs. The device characteristics were investigated measuring electroluminescence and current-voltage characteristic curves and analyzed by computational modeling of current spreading characteristics.