• 한국입자에어로졸학회지
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• 제6권2호
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• pp.51-59
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• 2010

ZnO quantum dots embedded in a silica matrix without agglomeration were synthesized from $TEOS:Zn(NO_3)_2$ solutions in one-step process by aerosol-gel method. It was successfully demonstrated that the size of ZnO Q-dots could be controlled from 2 to 7 mm verified by a high resolution transmission electron microscope observation. The line scanning energy dispersive X-ray spectroscopy(EDS) revealed that the Q-dots existed preferentially inside SiO2 sphere when Zn/Si < 0.5. However, the Q-dots distributed homogeneously all over the sphere when Zn/Si > 1.0. Blue-shifted UV/Vis absorption peak observation confirmed the quantum size effect on the optical properties. The photoluminescence(PL) emission peaks of the powders at room temperature were consistent with previous reports in the following aspects: 1) PL characteristics are dominated by two peaks of deep-level defect-related emissions at 2.4 - 2.8 eV, 2) the first defect-related peak at 2.4 eV was blue shifted due to the quantum size effect with decreasing the concentration of $Zn(NO_3)_2$(decreasing the size of ZnO q dots). More interestingly, the existence of surface-exposed ZnO q dots affects greatly the second defect PL peak at 2.8 eV.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.1057-1059
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• 2002

ZnO-Si-ZnO multi-layer thin films have been deposited by pulsed laser deposition (PLD). And then, the films have been annealed at $300^{\circ}C$ in oxygen ambient pressure. Electrical properties of the films were improved slightly than ZnO thin film without Si layer. Also, the optical and structural properties changed by Si layer in ZnO thin film. The optical and structural properties of Si-doped ZnO thin films were characterized by PL(Photoluminescence) and XRD(X-ray diffraction method) respectively. Electrical properties were measured by van der Pauw Hall measurements.

• 한국진공학회지
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• 제15권5호
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• pp.541-546
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• 2006

본 연구에서는 박막형 $ZnGa_2O_4:Mn$ 산화물 형광체의 음극선루미느센스 특성과 구조적 성질에 대하여 field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), photoluminescence (PL), 그리고 cathodoluminescence (CL) 방법을 이용하여 조사하였다. $ZnGa_2O_4:Mn$ 형광체 타겟으로부터 $Mn^{2+}$ 이온의 $^4T_1{\rightarrow}^6A_1$ 전이에 의한 506nm 파장에서의 PL emission 스펙트럼이 관찰되었다. 색좌표는 x = 0.09, y = 0.67 이었다. $ZnGa_2O_4:Mn$ 박막의 여기 스펙트럼은 $Mn^{2+}$ 이온 흡수에 의한 294 nm의 피크 파장을 나타내었다. 낮은 압력에서 증착한 $ZnGa_2O_4:Mn$ 형광체 박막은 고밀도의 치밀한 단면구조를 보였고, 높은 세기의 음극선루미느센스가 505 nm 피크 파장에서 나타났다. 표면 거칠기가 음극선루미느센스의 세기에 미치는 영향은 관찰되지 않았다.

• 한국재료학회지
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• 제11권10호
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• pp.889-894
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• 2001

2wt% $Al_2O_3-doped$ ZnO (AZO) thin films were deposited on sapphire (0001) single crystal substrate by parellel type rf magnetron sputtering at 55$0^{\circ}C$. The as-grown AZO thin films was polycrystalline and showed only broad deep defect-level photoluminescence (PL). In order to examine the change of PL property, AZO thin films were annealed in $N_2$ (N-AZO) and $H_2$ (H-AZO) at the temperature of $600^{\circ}C$~$1000^{\circ}C$ through rapid thermal annealing. After annealed at $800^{\circ}C$, N-AZO shows near band edge emission (NBE) with very small deep-level emission, and then N-AZO annealed at $900^{\circ}C$ shows only sharp NBE with 219 meV FWHM. In Comparison with N-AZO, H-AZO exhibits very interesting PL features. After $600^{\circ}C$ annealing, deep defect-level emission was quire quenched and NBE around 382 nm (3.2 eV) was observed, which can be explained by the $H_2$passivation effect. At elevated temperature, two interesting peaks corresponding to violet (406 nm, 3.05 eV) and blue (436 nm, 2.84 eV) emission was firstly observed in AZO thin films. Moreover, peculiar PL peak around 694 nm (1.78 eV) is also firstly observed in all the H-AZO thin films and this is believed good evidence of hydrogenation of AZO. Based on defect-level scheme calculated by using the full potential linear muffin-tin orbital (FP-LMTO), the emission 3.2 eV, 3.05 eV, 3.84 eV and 1.78 eV of H-AZO are substantially deginated as exciton emission, transition from conduction band maximum to $V_{ Zn},$ from $Zn_i$, to valence band maximum $(V_{BM})$ and from $V_{o} to V_BM}$, respectively.

• Advances in nano research
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• 제5권3호
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• pp.193-201
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• 2017

ZnO, ZnO: Cu, Ga, and ZnO: Cu, Ga, Ag thin films were obtained by oxidization of ZnS and ZnS: Cu, Ga films deposited onto glass substrates by electron-beam evaporation from ZnS and ZnS: Cu, Ga targets and from ZnS: Cu, Ga film additionally doped with Ag by the closed space sublimation technique at atmospheric pressure. The film thickness was about $1{\mu}m$. The oxidation was carried out at $600-650^{\circ}C$ in air or in an atmosphere containing water vapor. Structural characteristics were investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM). Photoluminescence (PL) spectra of the films were measured at 30-300 K using the excitation wavelengths of 337, 405 and 457.9 nm. As-deposited ZnS and ZnS: Cu, Ga films had cubic structure. The oxidation of the doped films in air or in water vapors led to complete ZnO phase transition. XRD and AFM studies showed that the grain sizes of oxidized films at wet annealing were larger than of the films after dry annealing. As-deposited doped and undoped ZnS thin films did not emit PL. Shape and intensity of the PL emission depended on doping and oxidation conditions. Emission intensity of the films annealed in water vapors was higher than of the films annealed in the air. PL of ZnO: Cu, Ga films excited by 337 nm wavelength exhibits UV (380 nm) and green emission (500 nm). PL spectra at 300 and 30 K excited by 457.9 and 405 nm wavelengths consisted of two bands - the green band at 500 nm and the red band at 650 nm. Location and intensities ratio depended on the preparation conditions.

• 한국재료학회지
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• 제18권12호
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• pp.669-672
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• 2008

Well-aligned Zinc oxide (ZnO) nanowires were synthesized on silicon substrates by a carbothermal evaporation method using a mixture of ZnO and graphite powder with Au thin film was used as a catalyst. The XRD results showed that as-prepared product is the hexagonal wurzite ZnO nanostructure and SEM images demonstrated that ZnO nanowires had been grown along the [0001] direction with hexagonal cross section. As-grown ZnO nanowires were coated with glucose oxidase (GOx) for glucose sensing. Glucose converted into gluconic acid by reaction with GOx and two electrons are generated. They transfer into ZnO nanowires due to the electric force between electrons and the positively charged ZnO nanostructures in PBS. Photoluminescence (PL) spectroscopy was employed for investigating the movements of electrons, and the peak PL intensity increased with the glucose concentration and became saturated when the glucose concentration is above 10 mM. These results demonstrate that ZnO nanostructures have potential applications in biosensors.

• E2M - 전기 전자와 첨단 소재
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• 제10권8호
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• pp.763-769
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• 1997

In this study we have synthesized Zno:Eu phosphors under various sintering atmospheres and temperatures. The analysis of X-ray diffractometer measurement indicates that for Zno:EuCl$_3$ phosphors sintered in air and vacuum 뗘 exists in the host lattice as Eu$_2$O$_3$and EuOCl respectively. From the photoluminescence for the phosphors sintered in vacuum Eu removes the broad-band emission of the ZnO host consequently isolating the red emission due to Eu$^{3+}$ ion and improves the color purity of red emission. The photoluminescence excitation and time resolving spectrum measurements suggest that energy-transfer process occurres from the self-activated defect center in ZnO host the Eu$^{3+}$ ion which exist in the host lattice in the form of EuOCl.

• 센서학회지
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• 제11권2호
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• pp.118-123
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• 2002

$ZnGa_2O_4$ 형광체 박막을 기판 온도를 $550^{\circ}C$에 고정시키고 산소 분압을 100, 200, 300 mTorr로 변화시키며 $Al_2O_3$(0001) 기판 위에 펄스 레이저 증착법을 이용하여 증착하였다. 다른 산소 분압에서 성장한 박막들의 미세 결정구조와 형광특성을 조사하였으며, 산소분압이 증가할수록 박막의 결정성이 변화하였으며 박막의 조성비가 다름을 형광특성을 통하여 알 수 있었다. 발광 스펙트럼은 460 nm에서 최고 피크값 을 나타내었으며, 300 nm에서 600 nm까지 갖는 넓은 밴드의 형광 특성을 나타내었다. 최적의 조건에서 성장된 박막의 형광 밝기를 고려해볼 때 $Al_2O_3$(0001) 기관이 우수한 $ZnGa_2O_4$ 형광체 박막을 성장시킬 수 있는 기판들 중 하나임을 확인하였다.

• 한국결정성장학회지
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• 제21권4호
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• pp.137-146
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• 2011

Vertically well-aligned ZnO nanowire (NW) arrays were synthesized directly on GaN/sapphire and Si substrate from Zn vapor deposition without catalysts. Experimental results showed that the number density, diameter, crystallinity and degree of the alignment of ZnO NWs depended strongly on both the substrate position and kind of the substrates used for the growth. The photoluminescence (PL) characteristics of the grown ZnO NW arrays exhibit a strong and sharp ultraviolet (UV) emission at 379 nm and a broad weak emission in the visible range, indicating that the obtained ZnO NWs have a high crystal quality with excellent optical properties. The as-grown ZnO NWs were characterized by using scanning electron microscopy (SEM), high resolution transmission electronic microscopy (HR-TEM), and X-ray diffraction (XRD).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.238-238
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• 2009

In this work, we investigated the effect of the Zn complex concentration and growth temperature on the growth of ZnO nanorod by hydrothermal method. The ZnO nanorods were performed at condition of the various Zn complex concentration and growth temperature, 0.02 ~ 0.08 M and 60 ~ 80 $^{\circ}C$, respectably. We found from the SEM results that the diameter and length of ZnO nanorods were with increasing the growth temperature and Zn complex concentration. However, the growth condition in the two parameters wasmore than sensitive compared to Zn complex concentration on increasing the growth rate. From photoluminescence(PL) analysis, the strong band-edge emission for ZnO nanorod grown at 80 $^{\circ}C$ with 0.08 M indicated the fine crystallinity. Therefore, the diameter and length of ZnO nanorods have been able to control through the control of front growth parameters. Also, these ZnO nanorods grown low temperature will be available as building block for transparence flexible device applications.