• 한국결정성장학회지
• /
• 제18권4호
• /
• pp.155-159
• /
• 2008

본 연구에서는 금속 Zn 팰렛을 원료 물질로 이용하여 열화학기상증착법으로 마이크로 크기의 프리스탠딩 ZnO/Zn 코어셀 다면체 구조물을 합성하였다. 마이크로 크기로 성장된 ZnO/Zn 코어셀 다면체의 형태와 구조적인 특성을 분석하기 위해서 주사전자현미경과 투과전자현미경을 이용하였다. 성장된 마이크로 크기의 다면체는 단결정 ZnO 나노막대 배열에 의해 둘러싸인 단결정 금속 Zn로 구성되어 있음을 확인할 수 있었다. 마이크로 크기의 단결정 Zn는 육방정 결정구조로 이루어져 있으며, 표면을 구성하고 있는 c-축 배향된 ZnO 나노막대가 10 nm와 100 nm 이하의 직경과 높이를 각각 가지며 육방정 결정구조의 단결정임을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
• /
• pp.429-429
• /
• 2008

The structural stability and the elastic modulus of hexagonal ZnO nanowires and nanotubes are investigated using atomistic simulations based on the shell model. The ZnO nanowire with (10-10) facets is energetically more stable than that with (11-20). Our calculations indicate that the structural change of ZnO nanowires with (10-10) facets is sensitive to the diameter. With decreasing the diameter of ZnO nanowires, the unit-cell length is increased while the bond-length is reduced due to the change of surface atoms. Unlike the conventional layered nanotubes, the energetic stability of single crystalline ZnO nanotubes is related to the wall thickness. The potential energy of ZnO nanotubes with fixed outer and inner diameters decreases with increasing wall thickness while the nanotubes with same wall thickness are independent of the outer and inner diameters. The transformation of single crystalline ZnO nanotubes with double layer from wurtzite phase to graphitic suggests the possibility of wall-typed ZnO nanotubes. The size-dependent Young's modulus for ZnO nanowires and nanotubes is also calculated. The diameter and the wall thickness play a significant role in the Young's modulus of single crystalline ZnO nanowires and nanotubes, respectively.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.256-256
• /
• 2008

We report epitaxial growth of ZnO thin films on (100) single-crystalline $LaAlO_3$ (LAO) substrates using pulsed laser deposition (PLD) at different substrate temperatures (400~$800^{\circ}C$). The structural and electrical properties of the films have been investigated by means of X-ray diffraction (XRD), atomic force microscope (AFM), transmission line method (TLM). The poly-crystalline of $\alpha$- and c-axis oriented ZnO film was formed at lower deposition temperature ($T_s$) of $400^{\circ}C$. At higher $T_s$, however, the films exhibit single-crystalline of $\alpha$-axis orientation represented by ZnO[$\bar{1}11$ || LAO <001>. The electrical properties of ZnO thin films depend upon their crystalline orientation, showing lower electrical resistivity values for $\alpha$-axis oriented ZnO films.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
• /
• pp.19-22
• /
• 2002

Three different ZnO nanomaterials (nanobelts, nanorods, and nanowires) were synthesized at three different substrate temperatures from the thermal evaporation of ball-milled ZnO powders at $1380^{\circ}C$. Transmission electron microscopy (TEM) revealed that the ZnO nanobelts are single crystalline with the growth direction perpendicular to the (010) lattice planes, and that the ZnO nanorods and nanowires are single crystalline with the growth directions perpendicular to the (001) and (110) lattice planes, respectively. In photoluminescence (PL), the peak energy of near band-edge (NBE) emission was determined for nanobelts, nanorods, and nanowires.

• 한국결정성장학회지
• /
• 제14권5호
• /
• pp.215-219
• /
• 2004

ZnO 에피박막을 사파이어 기판의 (0001)면 상에 RF magnetron sputtering 법으로 성장하였다. 박막의 성장속도는 약 0.1~0.2$\mu\textrm{m}$/hr 였으며, 기판온도가 $600^{\circ}C$일 때, 약 400~500nm두께의 단결정상의 박막을 성장할 수 있었다. 성장된 단결정상 박막에 대하여 XRD분석과 TEM을 이용하여 박막의 품질과 미세구조를 평가하였다.

• Transactions on Electrical and Electronic Materials
• /
• 제4권5호
• /
• pp.1-5
• /
• 2003

ZnO nanobelts, nanorods, and nanowires were synthesized at three different substrate temperatures from the thermal evaporation of ball-milled ZnO powders at 1380$^{\circ}C$. Transmission electron microscopy (TEM) revealed that the ZnO nanobelts are single crystalline with the growth direction perpendicular to the (010) lattice planes, and that the ZnO nanorods and nanowires are single crystalline with the growth directions perpendicular to the (001) and (110) lattice planes, respectively. In cathodoluminescence (CL), the peak energy of near bandedge (NBE) emission was determined for nanobelts, nanorods, and nanowires.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.39-39
• /
• 2010

The authors have an extensive study of photoluminescences for Zn-polar and O-polar faces of single-crystalline ZnO bulks. In the photoluminescence (PL) spectra at 10 K, Zn-polar and O-polar faces show a common emission feature: neutral donor-bound excitons and their longitudinal-optical (LO) phonon replicas are strong, and free excitons are very weak. However, in the PL spectra at room temperature (RT), Zn-polar and O-polar faces show extremely different emission characteristics: the emission intensity of Zn-polar face is 30 times larger than that of O-polar face, and the band edge of Zn-polar face is 33 meV red-shifted from that of O-polar face. The temperature dependence of photoluminescence indicates that the PL spectra at RT are closely associated with free excitons and their phonon-assisted annihilation processes. As a result, it is found that the RT PL spectra of Zn-polar face is dominated by the first-order LO phonon replica of A free excitons, while that of O-polar face is determined by A free excitons. This is ascribed that Zn-polar face has larger exciton-phonon coupling strength than O-polar face.

• 한국결정성장학회지
• /
• 제14권6호
• /
• pp.253-256
• /
• 2004

단결정상의 ZnO 에피 박막 성장을 사파이어 기판의 (0001)면 상에 RF magnetron sputtering 법으로 수행하였다. 200～$600^{\circ}C$까지의 기판의 온도를 변화하여 가면서 ZnO 에피 박막의 성장 거동을 조사하였으며, 성장된 ZnO 박막에 대하여 산소분위기에서 400, 600, $800^{\circ}C$에서 각각 아닐링을 하여 이에 대한 광 특성을 평가하였다. Hall measurement에 의해 측정 된 carrier concentratin은 $600^{\circ}C$에서 아닐링하여 $2.6${\times}$10^{16}\textrm{cm}^{-3}$이었다.

• 한국진공학회지
• /
• 제18권4호
• /
• pp.259-265
• /
• 2009

본 연구에서는 열증착법을 이용하여 합성된 단결정의 산화아연 나노선들을 이용하여 전계효과트랜지스터를 제작하여 광학, 표면반응 및 전기화학적인 거동들에 대한 기초 연구들을 수행하였다. 100 nm의 지름과 길이 5 um 길이를 갖는 단결정 산화아연나노선의 전자 농도와 이동도는 각각 $1.30{\times}10^{18}cm^{-3}$과 $15.6cm^2V^{-1}s^{-1}$이었으며, 자외선을 나노선에 조사한 경우 약 400배 정도 전류가 증가하였다. 또한 나노선들은 여러 농도의 수소와 일산화탄소에 대해 잘 알려진 표면반응으로 기인한 기체 감지 특성을 보였고, 0.1 M NaCl 전해질 내에서 전형적인 산화아연의 나노선의 전기적 특성을 유지함을 확인하였다.

• Progress in Superconductivity
• /
• 제4권1호
• /
• pp.14-18
• /
• 2002

We had succeeded to grow bulk sing1e crystals of La／sub 2-x／Sr／sub x／$CuO_4$by the traveling solvent floating zone method (TSFZ), and to prepare La／sub 2-x／Sr／sub x／CuO$_4$single-crystalline thick films on the Zn-doped La$_2$$CuO_4$ substrate by new liquid phase epitaxial technique using an infrared heating furnace (IR-LPE). In this paper, Ireview growth of bulk single crystals and single-crystalline thick films of La／sub 2-x／Sr／sub x／$CuO_4$, and discuss on their device properties to develop high speed integrated electronic devices.