The effects of Pulsed Green Laser Annealing for Carbon NanoWalls (CNWs)

2013 ◽  
Vol 1505 ◽  
Author(s):  
Norihito Kawaguchi ◽  
Akihiko Yoshimura
Keyword(s):  
Energy Density ◽  
Laser Irradiation ◽  
Laser Annealing ◽  
Laser Energy ◽  
Green Laser ◽  
Laser Energy Density ◽  
Oriented Crystal ◽  
Peak Intensity ◽  
Carbon Nanowalls ◽  
Band Spectra

ABSTRACTThe effects of the pulsed green laser annealing at ambient nitrogen for two different heights-CNWs grown on silicon substrate were investigated on the crystallinity and morphology using Raman spectroscopy, SEM, TEM and XPS. For the 1μm height-CNWs, the peak intensity of D-band spectra decreased as the laser energy density increased up to 1.3Jcm-2, ID/IG ratio decreased from 2.5 to 0.7. The crystallinity of CNWs was improved by the laser irradiation. For the 1μm height-CNWs irradiated above 1.5Jcm-2, the height of CNWs decreased gradually as the laser energy density increased, it was clarified that the surfaces of CNWs were vaporized by the laser irradiation. For the 20μm height-CNWs, the peak intensity of D band spectra also decreased until the laser energy density increased up to 0.8Jcm-2, ID/IG ratio decreased from 1.6 to 0.5. From the TEM observation of CNWs irradiated at 0.8 Jcm-2, it was confirmed that the laser irradiation changed CNWs to be highly oriented crystal structure. However above 0.8Jcm-2, the crystallinity was deteriorated due to the vaporization of CNWs as the same as the 1μm height-CNWs. The pulsed green laser annealing is effective to improve the crystallinity of CNWs on optimal laser energy density for both height-CNWs, the higher laser energy densities vaporized the CNWs and changed the morphology and crystallinity of CNWs.

Formation of Q-carbon by adjusting sp3 content in diamond-like carbon films and laser energy density of pulsed laser annealing

Carbon ◽  
2020 ◽  
Vol 167 ◽  
pp. 504-511 ◽  
Author(s):  
Hiroki Yoshinaka ◽  
Seiko Inubushi ◽  
Takanori Wakita ◽  
Takayoshi Yokoya ◽  
Yuji Muraoka
Keyword(s):  
Energy Density ◽  
Laser Annealing ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Carbon Films ◽  
Laser Energy Density ◽  
Diamond Like Carbon ◽  
Pulsed Laser Annealing

Discharge-Pumped VUV F2 Molecular Laser Annealing of Heavily Se+-Implanted GaAs

1993 ◽  
Vol 316 ◽  
Author(s):  
Hajime Shibata ◽  
Yunosuke Makita ◽  
Kawakatsu Yamada ◽  
Yutaka Uchida ◽  
Sabro Satoh
Keyword(s):  
Energy Density ◽  
Raman Scattering ◽  
Laser Annealing ◽  
Laser Energy ◽  
Laser Energy Density ◽  
Furnace Annealing ◽  
Implantation Energy ◽  
Molecular Laser ◽  
First Time ◽  
Ion Implanted

ABSTRACTThe capability of discharge-pumped vacuum ultraviolet F2 molecular laser for laser annealing of heavily ion implanted semiconductor was demonstrated for the first time using Se+ heavily ion implanted GaAs. Cr-doped semi-insulationg GaAs wafers were used as the substrates, and the Se+ implantation energy and dose were controlled to 100 keV and 1× 1015 cm-2, respectively. Samples were annealed using a F2 molecular laser ( wavelength = 157 nm ) with a single pulse ( width ~ 20 ns ) in the energy density range from 200 to 800 mJ/cm2 in a nitrogen atmosphere. In addition, furnace annealing was done on separate samples at 850 ºC for 20 minutes in a purified hydrogen atmosphere for comparison. Characterization of the samples was carried out using Raman scattering and ellipsometry. The laser annealed samples exhibited intense Raman scattering LO phonon peaks whose intensity increased with increasing laser power density, whereas the furnace annealed samples exhibited a very weak LO phonon peak. It was demonstrated for the first time that VUV photons can be very effective in annealing ion implantation damage as compared with conventional furnace annealing. The behavior of Raman scattering spectra as a function of laser energy density was explained quantitatively by a “spatial correlation” model. The model made it possible to estimate the average size of the recovered crystal regions in samples for any given laser energy density.

Laser annealing of laser additive–manufactured Ni-Ti structures: An experimental–numerical investigation

2016 ◽  
Vol 232 (6) ◽  
pp. 1054-1067 ◽  
Author(s):  
S Shiva ◽  
IA Palani ◽  
CP Paul ◽  
B Singh
Keyword(s):  
Energy Density ◽  
Laser Annealing ◽  
Laser Energy ◽  
Experimental Studies ◽  
Mechanical Systems ◽  
Laser Energy Density ◽  
Phase Transformation Temperature ◽  
Scanning Calorimetry ◽  
Homogeneous Microstructure ◽  
Micro Electro Mechanical Systems

Tailored structures of Ni-Ti shape memory alloys for micro-electro-mechanical systems can be fabricated using laser additive manufacturing, and requisite homogeneous microstructure for predictive design and fabrication of micro-electro-mechanical systems devices can be achieved by annealing. Investigation has been performed on the laser annealing of laser additive–manufactured Ni-Ti structures using a pulsed green laser through numerical simulation and experimental studies. The parametric dependence showed that a laser energy density of 1100 mJ cm−2 has a considerable influence in annealing of Ni-Ti structures. The surface morphology, phase transformation temperature and microstructure of laser-annealed Ni-Ti structures were studied with scanning electron microscopy, differential scanning calorimetry, X-ray diffraction and atomic force microscopy. Laser energy density of 1100 mJ cm−2 was used for annealing the samples as identified in the simulation. Surface annealing of Ni-Ti led to a uniform surface of the material with an increase in grain size and surface roughness. A decrease in the micro-hardness of the samples was obtained as a result of laser annealing. Thus, the investigations demonstrated the improved properties of laser additive–manufactured Ni-Ti structures by laser annealing.

Er-Doping in Silicon by Pulsed Laser Irradiation

1993 ◽  
Vol 301 ◽  
Author(s):  
Kenshiro Nakashima
Keyword(s):  
Energy Density ◽  
Laser Irradiation ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Laser Energy Density ◽  
Er Doping ◽  
Erbium Ions ◽  
State Regime ◽  
Er Doped ◽  
Pulsed Laser Irradiation

ABSTRACTErbium ions were successfully doped in silicon by pulsed laser irradiation above the threshold laser energy density. Photoluminescence peaks at 1.54, 1.59 and 1.64 µm from Er-optical centers were observed after annealing of Er-doped samples. The intensity of the 1.54 µm Er-emission band increased upon increase in the laser energy density, and then gradually decreased after reaching the maximum, due to the laser sputtering of the silicon substrate. Oxygen atoms, which were unintentionally codoped with Er-ions, were found to be distributed in the same region as in Er-ions, and were suggested to play roles to activate Er-optical centers. The maximum concentration of Er-ions doped in the solid state regime were estimated to be the order of 1018 cm−3 by the Rutherford backscattering measurements.

Electrical Properties of Solid Phase Crystallized Silicon Films

2001 ◽  
Vol 664 ◽  
Author(s):  
Tadashi Watanabe ◽  
Hajime Watakabe ◽  
Toshiyuki Sameshima
Keyword(s):  
Heat Treatment ◽  
Electrical Conductivity ◽  
Energy Density ◽  
Laser Irradiation ◽  
Carrier Mobility ◽  
Crystalline Silicon ◽  
Solid Phase ◽  
Laser Energy ◽  
Silicon Films ◽  
Laser Energy Density

ABSTRACTIn this study, the carrier mobility and density for solid phase crystallized (SPC) silicon films fabricated at 600 °C for 48 hours are analyzed by free carrier optical absorption. The carrier mobility is 40 cm2/Vs for SPC films doped with 6×1019-cm−3-phosphorus atoms. This analysis suggests the SPC films have fine crystalline grains closed to single crystalline silicon. In addition, initial carrier density was 3×1019 cm−3, which increased to 6×1019 cm−3by XeCl excimer laser irradiation of 500mJ/cm2. The inactivated regions in SPC films are reduced by laser irradiation. However, the electrical conductivity after laser irradiation for SPC films doped with 6×1018-cm−3-phosphorus atoms decreased from 3.3 to 0.018 S/cm as laser energy density increased to 500mJ/cm2. On the other hand, the electrical conductivity increased from 14.7 to 31.3 S/cm with similar increase of laser energy density after H2O vapor heat treatment at 260°C for 3 hours with 1.3 MPa. Furthermore, the characteristics of n-channel TFTs fabricated with initial SPC films as well as SPC films which was irradiated by laser at 425mJ/cm2 are also researched. The threshold voltage is decreased from 3.8 to 2.0 V by laser irradiation. Threshold voltages of both cases are decreased from 3.8 to 2.4 V for no-laser irradiation and from 2.0 to 0.8 V for laser irradiation, after H2O vapor heat treatment at 310°C for 1 hour with 9.0MPa. Based on the above trial, the defect reduction method combining laser irradiation and H2O vapor heat treatment has proved to be very effective for SPC films and SPC TFTs.

Fast-Pulse Excimer-Laser-Induced Processes in a-Si:H

1989 ◽  
Vol 164 ◽  
Author(s):  
K. Winer ◽  
R.Z. Bachrach ◽  
R.I. Johnson ◽  
S.E. Ready ◽  
G.B. Anderson ◽  
...  
Keyword(s):  
Energy Density ◽  
Excimer Laser ◽  
Impurity Concentration ◽  
Laser Annealing ◽  
Laser Energy ◽  
Laser Energy Density ◽  
Excimer Laser Annealing ◽  
Near Surface ◽  
Pulse Excimer Laser ◽  
Fast Pulse

AbstractThe effects of fast-pulse excimer laser annealing of a-Si:H were investigated by measurements of electronic transport properties and impurity concentration depth profiles as a function of incident laser energy density. The dc dark conductivity of laser-annealed, highly-doped a-Si:H increases by a factor of ∼350 above a sharp laser energy density threshold whose magnitude increases with decreasing impurity concentration and which correlates with the onset of hydrogen evolution from and crystallization of the near-surface layer. The similarities between the preparation and properties of laser-crystallized a-Si:H and pc-Si:H are discussed.

Effect of Excimer Laser Annealing on Optical Properties of GaN Films Deposited by R.F. Magnetron Sputtering

2001 ◽  
Vol 693 ◽  
Author(s):  
Man Young Sung ◽  
Woong-Je Sung ◽  
Yong-Il Lee ◽  
Chun-Il Park ◽  
Woo-Boem Choi ◽  
...  
Keyword(s):  
Thin Films ◽  
Energy Density ◽  
Magnetron Sputtering ◽  
Buffer Layer ◽  
Excimer Laser ◽  
Laser Annealing ◽  
Laser Energy ◽  
Laser Energy Density ◽  
Excimer Laser Annealing ◽  
Zno Buffer Layer

Abstract:GaN thin films on sapphire were grown by RF magnetron sputtering with ZnO buffer layer. The tremendous mismatch between the lattices of GaN and sapphire can be partly overcome by the use of thin buffer layer of ZnO. The dependence of GaN film quality on ZnO buffer layer was investigated by X-ray diffraction(XRD). The properties of the sputtered GaN are strongly dependent on ZnO buffer layer thickness. The optimum thickness of ZnO buffer layer is around 30nm. Using XRD analysis, we have found the optimal substrate temperature which can grow high quality GaN thin film. In addition, the effect of excimer laser annealing(ELA) on structural and electrical properties of GaN thin films was investigated. The surface roughness and images according to the laser energy density were investigated by atomic force microscopy(AFM) and it was confirmed that the crystallization was improved by increasing laser energy density.

Raman Measurements on Graphite Modified by High Power Laser Irradiation

1984 ◽  
Vol 35 ◽  
Author(s):  
J. Steinbeck ◽  
G. Braunstein ◽  
M.S. Dresselhaus ◽  
B.S. Elman ◽  
T. Venkatesan
Keyword(s):  
Energy Density ◽  
Laser Pulse ◽  
Laser Irradiation ◽  
High Power ◽  
Laser Energy ◽  
Laser Pulses ◽  
Laser Energy Density ◽  
High Power Laser ◽  
Power Laser ◽  
Raman Microprobe

AbstractThe behavior of highly anisotropic materials under short pulses of high power laser irradiation has been studied by irradiating highly oriented pyrolytic graphite (HOPG) with 30 nsec Ruby-laser pulses with energy densities between 0.1 and 5.0J/cm2. Raman spectroscopy has been used to investigate the laser-induced modifications to the crystalline structure as a function of laser energy density of the laser pulse. A Raman microprobe was used to investigate the spatial variations of these near-surface regions. The irradiation of HOPG with energy densities above ~ 0.6J/cm2 leads to the appearance of the ~ 1360 cm-1 disorder-induced line in the first order Raman spectrum. The intensity of the ~ 1360cm-1 line increases with increasing laser energy density. As the energy density of the laser pulse reaches about 1.0J/cm2, the ~ 1360cm-1 line and the ~ 1580cm-1 Raman-allowed mode broaden and coalesce into a broad asymmetric band, indicating the formation of a highly disordered region, consistent with RBS-channeling measurements. However, as the laser energy density of the laser pulses is further increased above 3.0J/cm2, the two Raman lines narrow and can again be resolved suggesting laser-induced crystallization. The Raman results are consistent with high resolution electron microscopy observations showing the formation of randomly oriented crystallites. Raman Microprobe spectra revealed three separate regions of behavior: (i) an outer unirradiated region where the material appears HOPG-like with a thin layer of material coating the surface, (ii) an inner irradiated region where the structure is uniform, but disordered, and (iii) an intermediate region between the other regions where the structure is highly disordered. The changes in structure of the inner region are consistent with the behavior observed with RBS and conventional Raman spectra. The identification of an amorphous carbon-like layer on the outer region is consistent with a large thermomechanical stress at the graphite surface, introduced by the high power laser pulse, and known to occur in metals.

Excimer (XeCl) Laser Annealing of PbZr0.4Ti0.6O3 Thin Film at Low Temperature for TFT FeRAM Application

2004 ◽  
Vol 830 ◽  
Author(s):  
W. X. Xianyu ◽  
H. S. Cho ◽  
J. Y. Kwon ◽  
H.X. Yin ◽  
T. Noguchi
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Energy Density ◽  
Laser Irradiation ◽  
Excimer Laser ◽  
Laser Annealing ◽  
Laser Energy ◽  
Perovskite Phase ◽  
Hysteresis Loops ◽  
Xecl Laser

ABSTRACTIn this study, we successfully produced PbZr0.4Ti0.6O3 (PZT (40/60)) thin films with high crystallinity and high remnant polarization (Pr) at low process temperatures using pulsed excimer (XeCl) laser irradiation. In our experiments, amorphous PZT films were prepared on Pt/Ti/SiO2/Si substrates by a sol-gel method. A two-step process was used to crystallize the amorphous thin films: the films were annealed at 550°C for 10 min to initiate the nucleation of the PZT perovskite phase, and then annealed with an excimer laser heating at 400°C in a 120 Torr nitrogen gas atmosphere. Laser energy density was varied from 150 to 750 mJ/cm2 per pulse. x-ray diffraction (XRD) patterns show that 150–200 mJ/cm2 range multi-shot excimer laser irradiation drastically improved the crystallinity of the PZT perovskite phase, and FESEM photographs show that the PZT thin film has uniform-sized crystal grains. The ferroelectric properties were found to depend on the laser energy density and shot number. Before the laser annealing, the films show hysteresis loops with low Pr and the loops do not saturate. After laser annealing, the films show highly saturated hysteresis loops, with the Pr increasing from 2.2 μC/cm2 to 23.0 μC/cm2. We also propose a new technology for fabrication of thin film transistor (TFT)-driven FeRAM devices on arbitrary insulator substrate such as on glass.

Electroless copper films deposited onto laser-activated aluminum nitride and alumina

1994 ◽  
Vol 9 (4) ◽  
pp. 1019-1027 ◽  
Author(s):  
M. J. DeSilva ◽  
A. J. Pedraza ◽  
D.H. Lowndes
Keyword(s):  
Energy Density ◽  
Aluminum Nitride ◽  
Laser Irradiation ◽  
Laser Energy ◽  
Annealing Treatment ◽  
Surface Region ◽  
Laser Energy Density ◽  
Copper Films ◽  
Near Surface ◽  
Electroless Copper

Metallization of ceramic substrates by laser activation and subsequent electroless deposition has been demonstrated recently in aluminum nitride and alumina. However, the bond strength between the electroless copper and the ceiamic substrate is weak (less than 14 MPa). Low temperature annealing of electroless copper films deposited on substrates activated at low laser energies strongly increases the adhesion strength. The effectiveness of the annealing for improving the metal-ceramic bonding is dependent upon the laser treatment performed on the substrate prior to deposition. Faster deposition kinetics are obtained for both substrates by increasing the laser energy density. On the other hand, an increase in the laser energy density leads to poor adhesion strengths. The dislocation microstructure produced during laser irradiation in aluminum nitride is analyzed as a possible cause of laser activation. Free aluminum produced by laser irradiation of aluminum nitride and of alumina is discussed as another factor of laser activation. The chemical and microstructural changes taking place in the near-surface region as a consequence of laser-induced processes are correlated with adhesion enhancement promoted by the annealing treatment.

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