• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.501-504
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• 2004

High quality GaN layer was obtained on 0001 sapphire substrate using ammonia($NH_3$) as a nitrogen source by gas source molecular beam epitaxy. As a result, RHEED is used to investigate the relaxation processes which take place during the growth of GaN. In-situ RHEED(reflection high electron energy diffraction) appeared streaky-like pattern. The full Width at half maximum of the x-ray diffraction(FWHM) rocking curve measured from plane of GaN has exhibited as narrow as 8arcmin and surface roughness was 7.83nm. Photoluminescence measurement of GaN was investigated at room temperature, where the intensity of the band edge emission is much stronger than that of deep level emission. The GaN epitaxy layer according to various growth condition was investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.823-827
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• 2001

The AgInS$_2$epilayers with chalcopyrite structure grown by using a hot-wall epitaxy (HWE) method have been confirmed to be a high quality crystal. From the optical absorption measurement, the temperature dependence of the energy band gap on the AgInS$_2$/GaAs was derived as the Varshni's relation of Eg(T)=2.1365 eV-(9.89${\times}$10$\^$-3/ eV)T$^2$/(2930+T). After the as-grown AgInS$_2$/GaAs was annealed in Ag-,S-, and In-atmosphere, the origin of point defects of the AgInS$_2$/GaAs has been investigated by using the photoluminescence (PL) at 10 K. The native defects of V$\_$Ag/, V$\_$s/, Ag$\_$int/, and S$\_$int/ obtained from PL measurement were classified to donors or acceptors type. And, we concluded that the heat-treatment in the S-atmosphere converted the AgInS$_2$/GaAs to optical p-type. Also, we confirmed that the In in the AgInS$_2$/GaAs did net from the native defects because the In in AgInS$_2$did exist as the form of stable bonds.

• Applied Science and Convergence Technology
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• v.24 no.3
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• pp.67-71
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• 2015

InP/InGaP quantum structures (QSs) were grown on GaAs (001) substrates by a migration-enhanced molecular beam epitaxy method. Temperature-dependent photoluminescence (PL) and emission wavelength-dependent time-resolved PL (TRPL) were performed to investigate the optical properties of InP/InGaP QSs as a function of migration enhanced epitaxy (MEE) growth cycles from 2 to 8. One cycle for the growth of InP QS consists of 2-s In and 2-s P supply with an interruption time of 10 s after each source supply. As the MEE growth cycle increases from 2 to 8, the PL peak is redshifted and exhibited different (larger, comparable, or smaller) bandgap shrinkages with increasing temperature compared to that of bulk InP. The PL decay becomes faster with increasing MEE cycles while the PL decay time increases with increasing emission wavelength. These PL and TRPL results are attributed to the different QS density and size/shape caused by the MEE repetition cycles. Therefore, the size and density of InP QSs can be controlled by changing the MEE growth cycles.

• Korean Journal of Materials Research
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• v.7 no.8
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• pp.707-713
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• 1997

HVPE(hydride vapor phase epitaxy)법으로 (111)MgAI$_{2}$ $O_{4}$기판위에 GaN 후막을 성장하였다. GaN를 성장하기 전에 기판에 표면을 GaCI로 처리한 수 성장하였을 때 이중 X선 회절 피크의 반치폭이 710 arcsec로서 N $H_{3}$로 처리한 후 성장한 GaN에 비하여 작았으며, 무색 투명의 경면상태가 얻어\ulcorner다. 113$0^{\circ}C$의 온도에서 성장한 GaN 의 광루미네센스(PL)특성과 동일하게 나타났다. 10K의 온도에서 측정된 PL 스펙트럼은 자유여기자와 속박여기자의 재결합천이에 의한 피크들과 Mg과 관련된 도너-억셉터 쌍 사이의 재결합 및 이의 1LO, 2LO, 3LO 및 4 LO 포논복제에 의한 피크들이 나타났다. 성장된 GaN는 n형의 전도성을나타내었으며, 캐리어 이동도와 농도는 각각 21.3$\textrm{cm}^2$/V ㆍsec와 4.2 x $10^{18}$$cm^{-3}$이었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.3
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• pp.105-110
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• 2003

The ZnSe epilayers were grown on the GaAs substrate by hot wall epitaxy. After the ZnSe epilayers treated in the vacuum-, Zn-, and Se-atmosphere, respectively, the defects of the epilayer were investigated by means of the low-temperature photoluminescence measurement. The dominant peaks at 2.7988 eV and 2.7937 eV obtained from the PL spectrum of the as-grown ZnSe epilayer were found to be consistent with the upper and the lower polariton peak of the exciton, $I_{2}$ ($D^{\circ}$, X), bounded to the neutral donor associated with the Se-vacancy. This donor-impurity binding energy was calculated to be 25.3 meV, The exciton peak, $I_{1}^{d}$ at 2.7812 eV was confirmed to be bound to the neutral acceptor corresponded with the Zn-vacancy. The $I_{1}^{d}$ peak was dominantly observed in the ZnSe/GaAs : Se epilayer treated in the Se-atmosphere. This Se-atmosphere treatment may convert the ZnSe/GaAs : Se epilayer into the p-type. The SA peak was found to be related to a complex donor like a $(V_{se}-V_{zn})-V_{zn}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.671-674
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• 2004

BSCCO thin films have been fabricated by epitaxy growth at an ultra-low growth rate. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. MgO(100) was used as a substrate. In order to appreciate stable existing region of Bi 2212 phase with temperature and ozone pressure, the substrate temperature was varied between 655 and 820 $^{\circ}C$ and the highly condensed ozone gas pressure(PO3) in vacuum chamber was varied between $2.0{\times}10^{-6}$ and $2.3{\times}10^{-5}$ Torr. Bi 2212 phase appeared in the temperature range of 750 and 795 $^{\circ}C$ and single phase of Bi 2201 existed in the lower region than $785\;^{\circ}C$. Whereas, $PO_3$ dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with $T_c$(onset) of about 90 K and $T_c$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as $CaCuO_2$ was observed in all of the obtained films.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.480.1-480.1
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• 2014

In this study, we suggest the new emitter formation applied solid phase epitaxy (SPE) growth process using rapid thermal process (RTP). Preferentially, we describe the SPE growth of intrinsic a-Si thin film through RTP heat treatment by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD). Phase transition of intrinsic a-Si thin films were taken place under $600^{\circ}C$ for 5 min annealing condition measured by spectroscopic ellipsometer (SE) applied to effective medium approximation (EMA). We confirmed the SPE growth using high resolution transmission electron microscope (HR-TEM) analysis. Similarly, phase transition of P doped a-Si thin films were arisen $700^{\circ}C$ for 1 min, however, crystallinity is lower than intrinsic a-Si thin films. It is referable to the interference of the dopant. Based on this, we fabricated 16.7% solar cell to apply emitter layer formed SPE growth of P doped a-Si thin films using RTP. We considered that is a relative short process time compare to make the phosphorus emitter such as diffusion using furnace. Also, it is causing process simplification that can be omitted phosphorus silicate glass (PSG) removal and edge isolation process.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.310-310
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• 2012

ZnO thin films were grown on porous silicon (PS) by plasma-assisted molecular beam epitaxy (PA-MBE). The optical properties of the ZnO thin films grown on PS were studied using room-temperature, low-temperature, and temperature-dependent photoluminescence (PL). The full width at half maximum (FWHM) of the near-band-edge emission (NBE) from the ZnO thin films was 98 meV, which was much smaller than that of ZnO thin films grown on a Si substrate. This value was even smaller than that of ZnO thin films grown on a sapphire substrate. The Huang-Rhys factor S associated with the free exciton (FX) emission from the ZnO thin films was found to be 0.124. The Eg(0) value obtained from the fitting was 3.37 eV, with ${\alpha}=3.3{\times}10^{-2}eV/K$ and ${\beta}=8.6{\times}10^3K$. The low- and high-temperature activation energies were 9 and 28 meV, respectively. The exciton radiative lifetime of the ZnO thin films showed a non-linear behavior, which was established using a quadratic equation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.11
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• pp.1005-1009
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• 2006

High quality three-dimensional (3D) heterostructures were constructed by selective area (SA) molecular beam epitaxy (MBE) using a specially patterned GaAs (001) substrate to improve the efficiency of tarrier transport. MBE growth parameters such as substrate temperature, V/III ratio, growth ratio, group V sources (As2, As4) were varied to calibrate the selective area growth conditions and the 3D GaAs-AlGaAs heterostructures were fabricated into the ridge type and the V-groove type. Scanning micro-photoluminescence $({\mu}-PL)$ measurements and the following analysis revealed that the gradually (adiabatically) coupled 1D-2DEG (electron gas) field effect transistor (FET) system was successfully realized. These 3D-heterostructures are expected to be useful for the realization of high-performance mesoscopic electronic devices and circuits since it makes it possible to form direct ohmic contact onto the (quasi) 1D electron channel.

• Transactions on Electrical and Electronic Materials
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• v.5 no.2
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• pp.50-54
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• 2004

The AgInS$_2$epilayers with chalcopyrite structure grown by using a hot-wall epitaxy (HWE) method have been confirmed to be a high quality crystal. From the optical absorption measurement, the temperature dependence of the energy band gap on the AgInS$_2$/GaAs was derived as the Varshni's relation of E$\_$g/(T) = 2.1365 eV - (9.89${\times}$10$\^$－3/ eV/K) T$^2$/(2930＋T eV). After the as-grown AgInS$_2$/GaAs was annealed in Ag－, S－. and In-atmosphere, the origin of point defects of the AgInS$_2$/GaAs has been investigated by using the photoluminescence (PL) at 10 K. The native defects of $V_{Ag}$, $V_s$, $Ag_{int}$, and $S_{int}$ obtained from PL measurement were classified to donors or accepters type. And, we concluded that the heat-treatment in the S- atmosphere converted the AgInS$_2$/GaAs to optical p-type. Also, we confirmed that the In in the AgInS$_2$/GaAs did not form the native defects because the In in AgInS$_2$did exist as the form of stable bonds.