Interaction of Laser Beam with PZT - Target and Observation of Laser - Induced Plume and Particle Ejection

이병우,Lee, Byeong-U Korean Society of Marine Engineers 1996 한국마린엔지니어링학회지 Vol.20 No.5

Laser-induced plume and laser-target interaction during pulsed laser deposition are demonstrated for a lead zirconate titanate (PZT). A KrF excimer laser (wavelength 248nm) was used and the laser was pulsed at 20Hz, with nominal pulse width of 20ns. The laser fluence was~$16J/cm^2,$ with 100mJ per pulse. The laser-induced plasma plume for nanosecond laser irradiation on PZT target has been investigated by optical emission spectra using an optical multichannel analyzer(OMA) and by direct observation of the plume using an ICCD high speed photography. OMA analysis showed two distinct ionic species with different expansion velocities of fast or slow according to their ionization states. The ion velocity of the front surface of the developing plume was about $10^7$cm/sec and corresponding kinetic energy was about 100eV. ICCD photograph showed another kind of even slower moving particles ejected from the target. These particles considered expelled molten parts of the target. SEM morphologies of the laser irradiated targets showed drastic melting and material removal by the laser pulse, and also showed the evidence of the molten particle ejection. The physics of the plasma(plume) formation and particle ejection has been discussed.

Pulsed laser chemical vapor deposition of a mixture of W, WO₂, and WO₃ from W(CO)₆ at atmospheric pressure

Jeong, K.,Lee, J.,Byun, I.,Seong, M.j.,Park, J.,Nam, H.s.,Lee, J. Elsevier S.A. 2017 Thin Solid Films Vol.626 No.-

Pulsed laser irradiation at 355nm was used to deposit tungsten (W) films from tungsten hexacarbonyls (W(CO)<SUB>6</SUB>) on transparent glass substrates in air. The time dependence of W deposition revealed that the reaction proceeded via nucleation and growth; photolytic decomposition initiated W nuclei, which acted as laser absorbers and grew by direct deposition on the nuclei, driven mainly by a pyrolytic process. In addition, the laser power dependence showed that the thickness of W films linearly increases with power; however, the thickness decreased significantly at a sufficiently high power to allow the evaporation of tungsten oxide. Various analyses (X-ray diffraction (XRD), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS)) identified α-W, WO<SUB>2</SUB>, and WO<SUB>3</SUB> in the deposited W films at 1.78-6.67W and at a scan rate of 4μm/s, and their compositional and microstructural changes according to laser power. The loss of carbon (C) is attributable to the background oxygen. An increase in laser power increased the oxygen content, the WO<SUB>3</SUB> to WO<SUB>2</SUB> ratio, and the size of W grains. The resistivity of W films was closely related to the oxygen concentration and microstructure of W. The minimum resistivity of ~80μΩ-cm was obtained at a power of from 3.56 to 4.0W, at which the effect of the laser-induced grain growth on resistivity is maximized, accompanied by the laser-enhanced oxidation of W.

Effect of Annealing and Oxygen Flow on the Optical Properties of ZnO Thin Film Grown by Using Pulsed Laser Deposition

이천,김재홍,Sung-Kwon Shin 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5

ZnO thin films have been deposited on (001) sapphire substrates by using a pulsed laser deposition (PLD) technique with a Nd:YAG laser at a wavelength of 266 nm. The deposition of the films was performed at substrate temperatures in the range of 300 ∽ 450 ℃ and at a flow rate of 100 ∽ 700 sccm before annealing treatment in an oxygen ambient. In order to investigate the effect of the annealing treatment on lms deposited at a fixed oxygen pressure of 350 sccm and a substrate temperature of 400 ℃, we annealed films at various temperatures after deposition. After annealing treatment in the oxygen ambient, the structural properties of the ZnO thin films were characterized by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical properties of lms were also characterized by using photoluminescence (PL). The crystallinity of the ZnO thin film was improved with increased annealing temperature. As the post-annealing temperature was increased, the intensity of the UV peak broadened and decreased. In particular, the position of the visible luminescence peak shifted to a shorter wavelength, and its intensity was increased at 800 ℃. ZnO thin films have been deposited on (001) sapphire substrates by using a pulsed laser deposition (PLD) technique with a Nd:YAG laser at a wavelength of 266 nm. The deposition of the films was performed at substrate temperatures in the range of 300 ∽ 450 ℃ and at a flow rate of 100 ∽ 700 sccm before annealing treatment in an oxygen ambient. In order to investigate the effect of the annealing treatment on lms deposited at a fixed oxygen pressure of 350 sccm and a substrate temperature of 400 ℃, we annealed films at various temperatures after deposition. After annealing treatment in the oxygen ambient, the structural properties of the ZnO thin films were characterized by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical properties of lms were also characterized by using photoluminescence (PL). The crystallinity of the ZnO thin film was improved with increased annealing temperature. As the post-annealing temperature was increased, the intensity of the UV peak broadened and decreased. In particular, the position of the visible luminescence peak shifted to a shorter wavelength, and its intensity was increased at 800 ℃.

Pulsed laser deposition of BaCo_0.4Fe_0.4Zr_0.1Y_0.1O_3-δ cathode for solid oxide fuel cells

Ryu, Sangbong,Lee, Sanghoon,Jeong, Wonyeop,Pandiyan, Arunkumar,Krishna Moorthy, Suresh Babu,Chang, Ikwhang,Park, Taehyun,Cha, Suk Won Elsevier 2019 Surface & coatings technology Vol.369 No.-

<P><B>Abstract</B></P> <P>We herein report a thin film deposition of perovskite BaCo<SUB>0.4</SUB>Fe<SUB>0.4</SUB>Zr<SUB>0.1</SUB>Y<SUB>0.1</SUB>O<SUB>3-δ</SUB> (BCFZY) by pulsed laser depositing (PLD) method for the use as a cathode in solid oxide fuel cells (SOFCs). The BCFZY powder was first synthesized via sol-gel method and pelletized to employ it as a target in PLD system. As a result, the PLD-deposited thin BCFZY film showed nano-porous morphology and preferred nano-architecture for cathode of SOFCs. The applicability of the thin film BCFZY to SOFC cathode was even confirmed by fabricating an SOFC with BCFZY cathode and operating it at 500 °C, where stable open-circuit voltage of 1.13 V was measured for an hour.</P> <P><B>Highlights</B></P> <P> <UL> <LI> BCFZY thin film is deposited as a SOFC cathode by pulsed laser deposition. </LI> <LI> PLD deposited BCFZY thin film has no defects and preserves perovskite structure. </LI> <LI> BCFZY thin film applied electrolyte support SOFC shows excellent oxygen reduction reaction activity. </LI> </UL> </P>

Effect of Deposition Rate on the Property of ZnO Thin Films Deposited by Pulsed Laser Deposition

Kim Jae-Won,Kang Hong-Seong,Lee Sang-Yeol The Korean Institute of Electrical Engineers 2006 Journal of Electrical Engineering & Technology Vol.1 No.1

ZnO thin films were deposited at different repetition rates of 5 Hz and 10 Hz by pulsed laser deposition. X-ray diffraction (XRD) full widths at half maximum (FWHMs) of (002) ZnO peak in ZnO thin film deposited at 5 Hz and 10 Hz was 0.22 and $0.26^{\circ}$, respectively. The grain size of ZnO thin film deposited at 5 Hz was larger than that of 10 Hz. The variation of repetition rates did not have an effect on the optical property of ZnO thin films. The degradation of the crystalline quality and surface morphology in ZnO thin film deposited at 10 Hz resulted from supersaturation effect by decrease of time interval between a ZnO particle arriving on a substrate by laser shot and a ZnO particle arriving on a substrate by next laser shot.

Effect of Deposition Rate on the Property of ZnO Thin Films Deposited by Pulsed Laser Deposition

Jae-Won Kim,Hong-Seong Kang,Sang-Yeol Lee 대한전기학회 2006 Journal of Electrical Engineering & Technology Vol.1 No.1

ZnO thin films were deposited at different repetition rates of 5 Hz and 10 ㎐ by pulsed laser deposition. X-ray diffraction (XRD) full widths at half maximum (FWHMs) of (002) ZnO peak in ZnO thin film deposited at 5 ㎐ and 10 ㎐ was 0.22 and 0.26°, respectively. The grain size of ZnO thin film deposited at 5 ㎐ was larger than that of 10㎐. The variation of repetition rates did not have an effect on the optical property of ZnO thin films. The degradation of the crystalline quality and surface morphology in ZnO thin film deposited at 10 ㎐ resulted from supersaturation effect by decrease of time interval between a ZnO particle arriving on a substrate by laser shot and a ZnO particle arriving on a substrate by next laser shot.

Pulsed laser deposition of functionally gradient diamond-like carbon (DLC) films using a 355nm picosecond laser

Cho, H.,Kim, S.,Ki, H. Elsevier Science 2012 Acta materialia Vol.60 No.18

In this study, functionally gradient diamond-like carbon (FGDLC) films are fabricated using a novel pulsed laser deposition technique to enhance adhesion strength. A 355nm picosecond laser beam is split into two beams, and the power of each split beam is changed individually by a motorized beam attenuator as a function of time. In this way, two laser beams with customized time-varying powers are available for ablating two different target materials. Two beams are irradiated on graphite and 316L stainless steel targets, respectively, in a vacuum chamber, and the produced dissimilar plasmas are mixed in space before they are deposited on a stainless steel 316L substrate. Using this method, we have built FGDLC films with a thickness of ~510nm, where the composition changes gradually from stainless steel to DLC in the direction of deposition. We have confirmed that FGDLC films show much higher adhesion strength than normal DLC films.

Effects of Two-Step Annealing on Pulsed Laser Ablated PZT Films

이동희 수원대학교 산업기술연구소 2000 산업기술연구소논문집 Vol.15 No.-

Deposition of PZT with UV laser ablation was applied for realization of thin film sensors and actuators. Deposition rate of more than 20nm/min was attained by pulsed KrF excimer laser deposition, which is fairly better than those obtained by the other methods. Perovskite phase was obtained at room temperature deposition with Fast Atom Beam(FAB) treatment and annealing. Smart MEMS(Micro electro-mechanical system) is now a subject of interest in the field of micro optical devices, micro pumps, AFM cantilever devices etc. It can be fabricated by deposition of PZT thin films and micromachining. PZT films of more than 1 micron thickness is difficult to obtain by conventional methods. This is the reason why the author applied excimer laser ablation for thin film deposition. The remanent polarization Pr of 700nm PZT thin film was measured, and the relative dielectric constant was determined to about 900 and the dielectric loss tangent was also measured to be about 0.04. XRD analysis shows that, after annealing at 650 degrees Centigrade in 1 hour, the perovskite structure would be formed with some amount of pyrochlore phase, as is the case of the annealing at 750 degrees Centigrade in 1 hour.

Pulsed Laser Deposition에 의해 SrRuO₃/SrTiO₃ 기판위에 여러 가지 증착온도에서 증착된 Pb(Zr_0.2Ti_0.8)O₃ 박막의 특성

이우성,정관호,김도훈,김시원,김형준,박종령,송영필,윤희근,이세민,최인혁,윤순길,Lee, Woo-Sung,Jung, Gwan-Ho,Kim, Do-Hun,Kim, Si-Won,Kim, Hyeong-Jun,Park, Jong-Ryong,Song, Young-Pil,Yoon, Hui-Kun,Lee, Sae-Min,Choi, In-Hyuk,Yoon, Soon-Gil 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.9

[ $Pb(Zr_{0.2}Ti_{0.8})O_3/SrRuO_3$ ] heteroepitaxial thin films were deposited at various temperatures on single crystal $SrTiO_3$ substrates by pulsed laser deposition and characterized for the microstructural and ferroelectric properties. The $SrTiO_3$ substartes etched by buffered oxide etch $(pH{\thickapprox}5.8)$ solution for 20s followed by the thermal annealing at $1000^{\circ}C$ for 1h showed the terrace ledges with a 0.4nm height. The $SrRuO_3$ bottom electrodes with a thickness of 52nm grown on $SrTiO_3$ single crystal also exhibit a terrace ledge similar to that of $SrTiO_3$. The PZT thin films were grown with an epitaxial relationship and showed typical P-E hysteresis loops shown at the epitaxial films. The 56nm thick-PZT films deposited at $650^{\circ}C$ exhibit a remanent polarization $(p_r)$ of $80{\mu}C/cm^2$ and a coercive field $(E_c)$ of 160kV/cm.

펄스레이저증착법에 의한 GaN 나노입자의 합성 및 특성분석

노정현,심승환,윤종원,박용주,심광보 한국결정성장학회 2003 한국결정성장학회지 Vol.13 No.2

ArF(193nm) 엑시머 레이저를 이용한 펄스레이저증착법(PLD)에 의해 GaN 소결체를 타겟 재료로 하여 $SiO_2$기판위에 GaN nanoparticles를 합성하였다. PLD 공정 중에는 100Pa, 50Pa, 10Pa및 1 Pa의 Ar gas 압력과 100mJ 및 200mJ의 레이저 에너지를 가하였다. 합성된 GaN nanoparticles는 XRD, SEM, TEM, XPS 및 optical absorption spectra 등에 의해 분석되었다. 합성된 GaN nanoparticles는 대체적으로 20~30nm의 입경을 갖는 균일한 분포를 하고 있었다. 또한, Ar 기체 압력이 낮아짐에 따라 합성된 GaN nanoparticles의 stoichiometry가 향상되고 optical band edge가 blueshift 경향을 나타내었다. 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.