• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1404-1405
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• 2006

Transparent ZnO thin films were deposited on quartz substrates by a KrF pulsed laser deposition (PLD) technique with different process conditions such as substrate temperature ($T_s$) and oxygen ambient pressure ($pO_2$). Surface morphology, crystal structure, and electrical properties of the ZnO films were investigated in order to characterize their thin film properties. The pulsed laser deposited ZnO films showed highly c-oriented crystalline structures depending on the process conditions: the highest FWHM (Full Width Half Maximum) value of (002) peak was observed for the ZnO film prepared at $T_{s}=550^{\circ}C$, $pO_2$=5mTorr and laser fluence of $2J/cm^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.162-164
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• 2004

Nanocrystalline silicon(nc-Si) thin films on the silicon substrates have been prepared by pulsed laser deposition(PLD). The optical and structural properties of films have been investigated depending on deposition temperature, annealing, and oxidation process. When the deposition temperature increased, photoluminescence(PL) intensity abruptly decreased and peaks showed red shift. Annealing process could reduce the number of defect centers. Oxidation had a considerable effect upon the formation and isolation of the nanocrystals. These results indicate that the formation mechanism of Si nanocrystals grown by PLD can be explained by three steps of growth, passivating defect centers, and isolation, sequentially.

• Progress in Superconductivity
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• v.6 no.1
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• pp.74-78
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• 2004

YBCO coated conductor is one of the most promising materials as a new generations wire especially for practical power applications. In this work, $YBa_2$$Cu_3$$O_{7}$ -$\delta$/(YBCO) coated conductors (CC) were deposited by pulsed laser deposition (PLD) from buffer layers to superconducting layer on hi-axially textured metal tape. The oxide multilayer buffered substrate of architectures of $CeO_2$/$YSZ/Y_2$$O_3$ was fabricated by PLD at steady status. Then YBCO layer was deposited on RABiTS substrate by stationary and reel-to-reel (R2R) continuous process and we compared with deposition conditions of both processes. The degree of texture of each layer was investigated using X-ray diffraction including $\theta$-2$\theta$ scans, $\omega$-scans and $\Phi$-scans analysis. Their surface morphology was observed by scanning electron microscopy (SEM). The FWHM of the X-ray $\Phi$-scans and $\Phi$-scans indicated that YBCO and buffer layers closely replicate the in-plane and out-of-plane texture of metal tape. Critical current (Ic) at 77 K, self-field of 75.8 A/cm-width, critical temperature (Tc) of 85 K, and critical current density (Ic) of 3.7 MA/$\textrm{cm}^2$ were measured from coated conductor deposited by stationary process. And coated conductor deposited by R2R continuous process had Ic of 57.5 A/cm-width, Tc of 86.5 K and Jc of 2.0 MA/$\textrm{cm}^2$. The film also exhibits a homogeneous and dense surface morphology.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.207-207
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• 2010

Both ZnO and GaN have excellent physical properties in optoelectronic devices such as blue light emitting diode (LED), blue laser diode (LD), and ultra-violet (UV) detector. The ZnO/GaN heterostructure, which has a potential to achieve the cost efficient LED technology, has been fabricated by using radio frequency (RF) sputtering, pyrolysis, metal organic chemical vapor deposition (MOCVD), direct current (DC) arc plasmatron, and pulsed laser deposition (PLD) methods. Among them, the PLD system has a benefit to control the composition ratio of the grown film from the mixture target. A 500-nm-thick ZnO film was grown by PLD technique on c-plane GaN/sapphire substrates. The post annealing process was executed at some varied temperature between from $300^{\circ}C$ to $900^{\circ}C$. The morphology and crystal structural properties obtained by using atomic force microscope (AFM) and x-ray diffraction (XRD) showed that the crystal quality of ZnO thin films can be improved as increasing the annealing temperature. We will discuss the post-treatment effect on film quality (uniformity and reliability) of ZnO/GaN heterostructures.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.108-109
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• 2007

Microstructure and electrical properties of Ga-doped ZnO (GZO) films grown on $Al_2O_3$ templates by Pulsed Laser Deposition (PLD) are investigated utilizing X-ray diffraction method and Hall measurement, respectively. In order to determine the optimized operating condition of the PLD, statistical design of experiment (DOE) is employed. It provides the systematic and efficient methodology for characterization and modeling of PLD processing with a relatively small number of experiments. The most optimized recipe of the process factors is obtained by response optimizer in Minitab.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.127-130
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• 2005

The properties of phosphorus doped ZnO multilayer thin films deposited on (001) sapphire substrates by pulsed laser deposition (PLD) were investigated by using annealing treatment at various annealing temperature after deposition. The phosphorus doped ZnO multilayer was composed of phosphorus doped ZnO layer and two pure ZnO layers on sapphire substrate. The structural. electrical and optical properties of the ZnOthin films were measured by X-ray diffraction (XRD). Hall measurements and photoluminescence (PL). As the annealing temperature optimized. the electrical properties of the ZnO multilayer showed a electron concentration of $1.56{\times}10^{16}/cm^3$, a resistivity of 17.97 ${\Omega}cm$. It was observed the electrical property of the film was changed by dopant activation effect as thermal annealing process

• Progress in Superconductivity and Cryogenics
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• v.11 no.2
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• pp.1-6
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• 2009

We report a successful fabrication of $high-J_c\;NdBa_2Cu_3O_{7-{\delta}}$ (NdBCO) films on $SrTiO_3$(STO) (100) substrates by pulsed laser deposition (PLD) in a relatively wide processing window. Under various oxygen pressures controlled by either 1%$O_2$/Ar mixture gas or pure $O_2$ gas, strongly c-axis oriented NdBCO films were grown at the substrate temperature $(T_s)\;of\;800^{\circ}C$ in 800 mTorr with 1%$O_2$/Ar gas and also in 400 and 800 mTorr with pure $O_2$ gas. These samples exhibited $T_c$ values over 90K and $J_c$ values of $2.8-3.5MA/cm^2$ at 77K in self-field (77K, sf). On the other hand, $J_c$ values over $1A/cm^2$ were obtained at the temperature regions of $700-830^{\circ}C$ in 800 mTorr with 1%$O_2$/Ar gas at those of $750-830^{\circ}C$ in 800 mTorr with pure $O_2$ gas. Unlike previous reports, resent results support that the PLD processing window for high-Jc NdBCO films is not narrow.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1219-1227
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• 2014

For development of the surface acoustic wave bandpass filter(SAW-BPF), we fabricated the high quality ZnO thin films through the step-by-step(double) deposition using two different deposition methods which are pulsed laser deposition(PLD) and RF sputtering techniques. The second growth of ZnO thin films was completed by RF sputtering method on the first ZnO thin films pre-deposited by PLD method. The characteristics of ZnO thin films were analyzed by XRD, SEM and AFM systems. The FWHM of ${\omega}$-scan analysis and the minimum RMS value of surface roughness of step-by-step grown ZnO thin films were $0.79^{\circ}$ and 1.108 nm respectively. As a result, the crystallinity and the preferred orientation of the grown ZnO thin films were kept good quality and the surface roughnesses of those were improved by post-annealing process as comparison with ZnO thin film fabricated by the conventional PLD technique only. Using these proposed ZnO thin films, we demonstrated the RF device such as SAW-BPF, built by the proposed ZnO thin films, shows that it has the bandwidth of 2.98 MHz and the insertion loss of 36.5 dB at the center frequency of 260.8 MHz, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.2
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• pp.79-82
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• 2003

GaN nanoparticles were synthesized by the pulsed laser deposition (PLD) process on $SiO_2$substrate after irradiating the surface of the GaN sintered pellet by the ArF (193 nm) excimer laser. At this moment Ar gas pressure of 100 Pa, 50 Pa, 10 Pa and 1 Pa were applied during the ablation process and laser power of 100 mJ and 200 mJ were also applied. The synthesized fan nanoparticles were characterized by XRD, SEM, TEM, XPS and optical absorption spectra. The synthesized GaN nanoparticles had the crystallite sizes of 20~30 nm, and besides, GaN nanoparticles synthesized under low Ar gas pressure compared to the others corresponded with stoichiometry, and the optical band edge of the GaN nanoparticles was blueshifted.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.138-141
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• 1999

For the enhancement of communication system performance, high quality filters are required. Conventional metal filters made of copper can be substituted by high quality high temperature superconductivity(HIS) flms for better performance. In order to reduce the size of the filter for the integration of device in the limited area, we have fabricated hairpin type filters using pulsed laser deposition(PLD) technique. The superconducting YBCO thin films have been grown on MgO substrates by PLD with Nd:YAC laser. The YBCO films were patterned by conventional wet-etching process. We have compared YBCO filters and copper filters which were made with the same spec. Simulated and measured frequency responses reveal that HIS YBCO hairpin type bandpass filters show better performance than copper filters.