• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
• /
• pp.200-202
• /
• 2004

ZnO thin films were grown at different plume-substrate angles by pulsed laser deposition(PLD). From the X-ray diffraction(XRD) result, all ZnO thin films were found to be well c-axis oriented and c-axis lattice constant approached the value of bulk ZnO as plume-substrate(P-S) angle decreased. The grain size of ZnO thin films measured by atomic force microscopy increased and the UV intensity of ZnO thin films investigated by photoluminescence increased as P-S angle decreased. It is found that the improvement of structural and optical properties mainly comes from the reduction of the flux of ablated species arriving on a substrate per a laser shot by tilting a substrate parallel to the plume propagation direction.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2012년도 추계학술대회 논문집
• /
• pp.591-592
• /
• 2012

• Transactions on Electrical and Electronic Materials
• /
• 제12권5호
• /
• pp.200-203
• /
• 2011

In this research, nitrogen (N)-doped zinc oxide (ZnO) thin films have been grown on a sapphire substrate by dielectric barrier discharge (DBD) in pulsed laser deposition (PLD). DBD has been used as an effective way for massive in-situ generation of N-plasma under conventional PLD process conditions. Low-temperature photoluminescence spectra of N-doped ZnO thin films provided near-band-edge emission after a thermal annealing process. The emission peak was resolved by Gaussian fitting and showed a dominant acceptor-bound excitation peak ($A^{\circ}X$) that indicated acceptor doping of ZnO with N. The acceptor binding energy of the N acceptor was estimated to be approximately 145 MeV based on the results of temperature-dependent photoluminescence (PL) measurements.

• 한국전기전자재료학회논문지
• /
• 제22권5호
• /
• pp.419-424
• /
• 2009

ZnO films doped with different contents of indium ($0.1{\sim}10$ at.%) were deposited on Si (111) substrate by Pulsed Laser Deposition (PLD). The structural, electrical and optical properties of the films were investigated using XRD, AFM, Hall and PL measurement. Results showed that un-doped ZnO film had (002) plane as the c-axis orientated growth, whereas indium doped ZnO films exhibited the peak of (002) and the weak (101) plane. In addition, in the indium doped ZnO films, the electron concentration is ten times higher than that of un-doped ZnO film, while the resistivity is ten times lower than that of un-doped ZnO film. The indium doped ZnO films have UV emission about 380 nm and show a red shift with increasing contents of indium. The I-V curve of the fabricated diode show the typical diode characteristics and have the turn on voltage of about 2 V.

• KIEE International Transactions on Electrophysics and Applications
• /
• 제5C권3호
• /
• pp.97-101
• /
• 2005

ZnO thin films were grown at different plume-substrate (P-S) angles of 90$^{\circ}$ (on-axis PLD), 45$^{\circ}$ and 0$^{\circ}$ (off-axis PLD) using pulsed laser deposition. The x-ray diffraction pattern exhibiting a dominant (002) and a minor (101) peak of ZnO indicates all films were strongly c-axis oriented. By observing of (002) peak, the FWHMs of ZnO (002) peaks decreased and c-axis lattice constant approached the value of bulk ZnO as P-S angle decreased. Whereas the carrier concentration of ZnO thin film deposited at P-S angle of 90$^{\circ}$ was ~ 10$^{19}$ /cm$^{3}$, the Hall measurement of ZnO thin films deposited at P-S angles of 0$^{\circ}$ and 45$^{\circ}$ was impossible due to the decrease of the carrier concentration by the improvement of stoichiometry and crystalline quality. By decreasing P-S angle, the grain size of the films and the UV intensity investigated by photoluminescence (PL) increased and UV peak position showed red shift. The improvement of properties in ZnO thin films deposited by off-axis technique was due to the decrease of repulsive force between a substrate and the particle in plume and the relaxation of supersaturation.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1996년도 춘계학술대회 논문집
• /
• pp.129-132
• /
• 1996

Surface modification like cone formation on Pulsed laser deposition (PLD) occurs in YBCO target surface irradiated by laser beam. Cone formation results in a reduction of deposition rate, so that it is significant obstacles to an efficient deposition process. With the change of various conditions such as the number of laser shot, target density, direction of incoming laser beam, we have systematically analyzed the modification of target surface. Because cones formed by beam-target interactions grow in direction of incoming laser beam, we have used the method of rotating the target position by 180$^{\circ}$ with the same number and position of laser shot. Experimental results of losing the directionality and changing the shape of cones formed on laser irradiated YBCO target surface is obtained by the SEM image. Also, we have observed that the size of cones formed on target by pulsed laser became larger with increasing the number of laser shots.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 초전도 자성체 연구회
• /
• pp.30-33
• /
• 2003

YBCO coated conductor, also called the 2nd generation high temperature superconducting wire, consists of oxide multi-layer hetero-epitaxial thin films. Pulsed laser deposition (PLD) is one of many film deposition methods used to make coated conductor, and is the one known to be the best to make superconducting layer so far. As a part of the effort to make long length coated conductor, the optimum deposition condition of YBCO film on single crystal substrate (SrTiO3) was investigated using PLD. Substrate temperature, oxygen partial pressure, and laser fluence were varied to find the best combination to grow high quality YBCO film.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
• /
• pp.361-363
• /
• 1995

High quality $Y_1Ba_2Cu_3O_{7-x}$ thin films have been fabricated by pulsed Nd:YAG laser deposition using an unusual 'off-axis' target-substrate geometry. Various properties of superconducting $Y_1Ba_2Cu_3O_{7-x}$ thin films have been studied systematically as a function of oxygen pressure during the deposition, in both 'on-axis' and the unusual 'off-axis' target substrate geometry. In the 'off-axis' geometry, one can completely eliminate the so-called 'laser droplets' form the thin surface and thus obtain smooth high qualify films. It is found that films with optimum structural and electrical properties are obtained at a lower oxygen pressure range during the 'off-axis' deposition when compared with that required in the 'on-axis' deposition geometry.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2009년도 추계학술발표대회
• /
• pp.6.2-6.2
• /
• 2009

Nanostructured materials arecurrently receiving much attention because of their unique structural andphysical properties. Research has been stimulated by the envisagedapplications for this new class of materials in electronics, optics, catalysisand magnetic storage since the properties derived from nanometer-scalematerials are not present in either isolated molecules or micrometer-scalesolids. This study presents the experimental results derived fromthe various functional materials processed in nano-scale using pulsed laserablation, since those materials exhibit new physical phenomena caused by thereduction dimensionality. This presentation consists of three mainparts to consider in pulsed laser ablation (PLA) technique; first nanocrystallinefilms, second, nanocolloidal particles in liquid, and third, nanocoating fororganic/inorganic hybridization. Firstly, nanocrystalline films weresynthesized by pulsed laser deposition at various Ar gas pressures withoutsubstrate heating and/or post annealing treatments. From the controlof processng parameters, nanocystalline films of complex oxides and non-oxidematerials have been successfully fabricated. The excellentcapability of pulsed laser ablation for reactive deposition and its ability totransfer the original stoichiometry of the bulk target to the deposited filmsmakes it suitable for the fabrication of various functionalmaterials. Then, pulsed laser ablation in liquid has attracted muchattention as a new technique to prepare nanocolloidal particles. Inthis work, we represent a novel synthetic approach to directly producehighly-dispersed fluorescent colloidal nanoparticles using the PLA from ceramicbulk target in liquid phase without any surfactant. Furthermore, novel methodbased on simultaneous motion tracking of several individual nanoparticles isproposed for the convenient determination of nanoparticle sizedistributions. Finally, we report that the GaAs nanocrystals issynthesized successfully on the surface of PMMA (polymethylmethacrylate)microspheres by modified PLD technique using a particle fluidizationunit. The characteristics of the laser deposited GaAs nanocrytalswere then investigated. It should be noted that this is the first successfultrial to apply the PLD process nanocrystals on spherical polymermatrices. The present process is found to be a promising method fororganic/inorganic hybridization.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 춘계학술대회 논문집 디스플레이 광소자 분야
• /
• pp.127-130
• /
• 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