• 한국재료학회:학술대회논문집
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• 한국재료학회 1998년도 IUMRS-ICEM ABSTRACT BOOK
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• pp.146.4-146
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• 1998

• 한국세라믹학회지
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• 제55권2호
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• pp.108-115
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• 2018

The increasing demands for three-dimensional (3D) electronic and optoelectronic devices have triggered interest in epitaxial growth of 3D semiconductor materials. However, most of the epitaxially-grown nano- and micro-structures available so far are limited to certain forms of crystal arrays, and the level of control is still very low. In this review, we describe our latest progress in 3D epitaxy of oxide and nitride semiconductor crystals. This paper covers issues ranging from (i) low-temperature solution-phase synthesis of a well-regulated array of ZnO single crystals to (ii) systematic control of the axial and lateral growth rate correlated to the diameter and interspacing of nanocrystals, as well as the concentration of additional ion additives. In addition, the critical aspects in the heteroepitaxial growth of GaN and InGaN multilayers on these ZnO nanocrystal templates are discussed to address its application to a 3D light emitting diode array.

• 한국표면공학회지
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• 제29권5호
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• pp.407-414
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• 1996

We have investigated the effects of H atoms on thin film growth processes and surface reactions. In the oxidation of Si, Si surfaces are passivated against the $O_2$ adsorption by terminating dangling bonds with H atoms. Moreover, the existence of Si-H bonds on Si(100) surfaces enhances the structural relaxation of Si-O-Si bonds due to a charge transfer from Si-Si back bonds. In the heteroepitaxial growth of a Si/Ge/Si(100) system, H atoms suppress the segregation of Ge atoms into Si overlayers since the exchange of Ge atoms with Si atoms bound with H must be accompanied with breaking of Si-H bonds. However, 3-dimensional island growth is also promoted by atomic H irradiation, which is considered to result from the suppression of surface migration of adsorbed reaction species and from the lowering of step energies by the H termination of dangling bonds.

• 한국재료학회지
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• 제4권6호
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• pp.687-694
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• 1994

선택적 LPE방법을 이용하여 (111)B GaAs 기판 상에 InP연속 박막을 성장하고 그 특성을 평가하였다. 적정 LPE성장조건으로 성장온도 $660^{\circ}C$, 과냉도 $5^{\circ}C$, 냉각속도 $0.4^{\circ}C$/min였으며, 연구된 온도 범위에서 성장온도가 증가할수록 표면형상이 개선되었고 ELO의 넓이가 증가하였다. Seed방향이 <112>방향에서 110-160$\mu \textrm{m}$ 정도의 최대 ELO 넓이가 얻어졌으며 60-80$\mu \textrm{m}$정도의 마스크 간격에서 연속박막을 용이하게 성장할 수 있었다. LPE 성장초기에 기판 용해 현상이 발생하였으며 이에 따라 성장박막의 조성이 대략 $In_{0.85}Ga_{0.15}$As$_{0.01}P{0.99}$으로 변화하고 InP/GaAs계면 및 박막 표면형상이 거칠어졌으나 기판의 성장 부위가 제한됨에 따라 통상적인 LPE박막에 비교하여 매우 개선된 표면형상을 얻을 수 있었다. 두개의 성장융액을 이용하여 1차 박막성장 후 다시 InP 박막을 성장하는 2단성장 방법을 사용하여 순수한 InP/GaAs박막을 성장할 수 있었으며 단면 TEM분석 결과 SLPE성장박막으로 전파하는 활주전위는 산화막 마스크에 의해 효과적으로 차단됨을 알 수 있었다.

• The Korean Journal of Ceramics
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• 제2권4호
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• pp.197-202
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• 1996

The highly oriented diamond particles were deposited on the mirror-polished (100) silicon substrates in the bell-jar type microwave plasma deposition system using a three-step process consisting if carburization, bias-enhanced nucleation and growth. By adjusting the geometry of the substrate and substrate holder, very dense disc-shaped plasma was formed over the substrate when the bias voltage was below -200V. Almsot perfectly oriented diamond films were obtained only in this dense disc-shaped plasma. From the results of the optical emission spectra of the dense disc-shaped plasma, it was found that the concentrations of atomic hydrogen and hydrocarbon radical were increased with negative bias voltage. It was also found that the highly oriented diamonds were deposited in the region, where the intensity ratios of carbonaceous species to atomic hydrogen are saturated.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.6-6
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• 2010

This paper describes that single crystal cubic silicon (3C-SiC) films have been deposited on carbonized Si(100) substrate using hexamethyldisilane(HMDS, $Si_2(CH_3)_6$) as a safe organosilane single-source precursor and a nonflammable mixture of Ar and $H_2$ gas as the carrier gas by APCVD at $1280^{\circ}C$. The 3C-SiC film had a very good crystal quality without defects due to viods, a very low residual stress.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.302.1-302.1
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• 2014

We report the growth of high quality zinc oxide (ZnO) thin films on amorphous glass substrates and their structural and optical characteristics. For the growth of ZnO films, mechanically exfoliated ultrathin graphite or graphene layers were used as an intermediate layer because ZnO does not have any heteroepitaxial relationship with the amorphous substrates, which significantly improved the crystallinity of the ZnO films. Structural and optical characteristics of the films were investigated using scanning and transmission electron microscopy, x-ray diffraction, and variable temperature photoluminescence spectroscopy. High crystallinity and excellent optical characteristics such as stimulated emission were exhibited from the high quality ZnO films grown on glass substrates.

• 한국전기전자재료학회논문지
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• 제36권5호
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• pp.500-504
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• 2023

In this study, the heteroepitaxial thin film growth of β-Ga₂O₃ was studied according to the position of the susceptor in mist-CVD. The position of the susceptor and substrate was moved step by step from the center of the hot zone to the inlet of mist in the range of 0~50 mm. It was confirmed that the average thickness increased to 292 nm (D1), 521 nm (D2), and 580 nm (D3) as the position of the susceptor moved away from the center of the hot zone region. The thickness of the lower region of the substrate is increased compared to the upper region. The surface roughness of the lower region of the substrate also increased because the nucleation density increased due to the increase in the lifetime of the mist droplets and the increased mist density. Therefore, thin film growth of β-Ga₂O₃ in mist-CVD is performed by appropriately adjusting the position of the susceptor (or substrate) in consideration of the mist velocity, evaporation amount, and temperature difference with the substrate, thereby determining the crystallinity of the thin film, the thickness distribution, and the thickness of the thin film. Therefore, these results can provide insights for optimizing the mist-CVD process and producing high-quality β-Ga₂O₃ thin films for various optical and electronic applications.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.284-284
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• 2016

Topological insulator (TI) is a bulk-insulating material with topologically protected Dirac surface states in the band gap. In particular, $Bi_2Se_3$ attracted great attention as a model three-dimensional TI due to its simple electronic structure of the surface states in a relatively large band gap (~0.3 eV). However, experimental efforts using $Bi_2Se_3$ have been difficult due to the abundance of structural defects, which frequently results in the bulk conduction being dominant over the surface conduction in transport due to the bulk doping effects of the defect sites. One promising approach in avoiding this problem is to reduce the structural defects by heteroepitaxially grow $Bi_2Se_3$ on a substrate with a compatible lattice structure, while also preventing surface degradation by encapsulating the pristine interface between $Bi_2Se_3$ and the substrate in a clean growth environment. A particularly promising choice of substrate for the heteroepitaxial growth is hexagonal boron nitride (h-BN), which has the same two-dimensional (2D) van der Waals (vdW) layered structure and hexagonal lattice symmetry as $Bi_2Se_3$. Moreover, since h-BN is a dielectric insulator with a large bandgap energy of 5.97 eV and chemically inert surfaces, it is well suited as a substrate for high mobility electronic transport studies of vdW material systems. Here we report the heteroepitaxial growth and characterization of high quality topological insulator $Bi_2Se_3$ thin films prepared on h-BN layers. Especially, we used molecular beam epitaxy to achieve high quality TI thin films with extremely low defect concentrations and an ideal interface between the films and substrates. To optimize the morphology and microstructural quality of the films, a two-step growth was performed on h-BN layers transferred on transmission electron microscopy (TEM) compatible substrates. The resulting $Bi_2Se_3$ thin films were highly crystalline with atomically smooth terraces over a large area, and the $Bi_2Se_3$ and h-BN exhibited a clear heteroepitaxial relationship with an atomically abrupt and clean interface, as examined by high-resolution TEM. Magnetotransport characterizations revealed that this interface supports a high quality topological surface state devoid of bulk contribution, as evidenced by Hall, Shubnikov-de Haas, and weak anti-localization measurements. We believe that the experimental scheme demonstrated in this talk can serve as a promising method for the preparation of high quality TI thin films as well as many other heterostructures based on 2D vdW layered materials.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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• pp.113-113
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• 2003

ZnO 박막은 p형 도핑방법이 점차 알려 지면서 최근 차세대 발광소자 재료로서 주목을 받고 있으며, 우수한 전자 이동도, 우수한 홀 이동도, 발광 스펙트럼(PL) 피크의 날카로움, 높은 free exciton binding energy, 방사선 노출에 대한 큰 내구성, 습식 식각이 가능, 동종 기판 사용이 가능함으로써 박막의 품질을 개선할 수 있고 제조공정을 간소화할 수 있는 등의 장점을 지니고 있어 이에 관련된 많은 연구들이 진행되고 있다. 특히 ZnO 박막을 차세대 발광소자로 응용하기 위해서는 고품질의 에피탁시 박막을 성장시켜야 하며 이를 위하여 MBE, MOCVD, PLD법 등 다양한 에피탁시 박막증착이 시도되고 있다. 또한 보다 양질의 ZnO 박막을 성장시키기 위해 적절한 단결정 기판 및 버퍼층의 탐색과 각 기판에 따른 ZnO 박막의 물성평가 작업도 진행되고 있다.