Femtosecond and Nanosecond Laser Pulse Crystallization of Thin a-Si:H Films on Non-Refractory Glass Substrates

2007 ◽  
Vol 131-133 ◽  
pp. 479-484 ◽  
Author(s):  
Vladimir A. Volodin ◽  
M.D. Efremov ◽  
G.A. Kachurin ◽  
S.A. Kochubei ◽  
A.G. Cherkov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Energy Density ◽  
Laser Pulse ◽  
Raman Scattering ◽  
Pulse Energy ◽  
Laser Wavelength ◽  
Nanosecond Laser ◽  
Glass Substrates ◽  
Pulse Energy Density ◽  
Krf Laser

Thin (90 nm) a-Si:H films on Corning 7059 glass substrates have been crystallized by 120 fs pulses of Ti:sapphire and nanosecond pulse XeCl and KrF excimer lasers. Initial films were deposited using low-temperature plasma enhanced deposition technique. The structural properties of the films were characterized using the spectroscopy of Raman scattering, excited by the argon laser (line 514.5 nm) and using electron microscopy. For the femtosecond pulse treatments the ablation threshold was found to be some more than 65 mJ/cm2. When pulse energy density was lower than ~30 mJ/cm2 no structural changes were observed. In optimal regimes the films were found to be fully crystallized with needle grain structure, according to the Raman scattering and electron microscopy data. Estimates show the pulse energy density was lower than the Si melting threshold, so non-thermal “explosive” impacts may play some role. The main result in nanosecond XeCl and KrF laser pulse crystallization is the narrower window between beginning of crystallization and ablation for KrF laser (wavelength 248 nm) than for the XeCl laser (wavelength 308 nm). So, the possibility of the femtosecond and nanosecond laser pulses to crystallize a-Si films on non refractory glass substrates was shown. The results obtained are of great importance for manufacturing of polycrystalline silicon layers on non-refractory large-scale substrates for giant microelectronics.

The influence of nanosecond laser pulse energy density for paint removal

Optik ◽  
2018 ◽  
Vol 156 ◽  
pp. 841-846 ◽  
Author(s):  
Xiaokui Li ◽  
Qiuhui Zhang ◽  
Xinzhi Zhou ◽  
Daoqiang Zhu ◽  
Quanxi Liu
Keyword(s):  
Energy Density ◽  
Laser Pulse ◽  
Pulse Energy ◽  
Laser Pulse Energy ◽  
Nanosecond Laser Pulse ◽  
Nanosecond Laser ◽  
Pulse Energy Density ◽  
Paint Removal

scholarly journals Спектральные характеристики свечения поверхности частиц каменных углей во время воздействия лазерных импульсов в режиме свободной генерации

2020 ◽  
Vol 128 (12) ◽  
pp. 1898
Author(s):  
Б.П. Адуев ◽  
Д.Р. Нурмухаметов ◽  
Я.В. Крафт ◽  
З.P. Исмагилов
Keyword(s):  
Energy Density ◽  
Laser Pulse ◽  
Pulse Energy ◽  
Laser Pulse Energy ◽  
Emission Spectra ◽  
Radiation Energy ◽  
Laser Pulses ◽  
Radiation Energy Density ◽  
Pulse Energy Density ◽  
Coal Particles

In this work, we investigated the glow spectra of coal fractions with dimensions 63 μm directly during the action of neodymium laser pulses (120 μs). Depending on the radiation energy density H, the emission spectra have a different character. The glow at the minimum values ​​of the laser pulse energy density Hcr (1) is associated with the ignition of small coal particles (~ 1 μm) present in the fractions and the ignition of reactive microprotrusions on the surface of the larger coal particles. The glow spectra at this stage are of a non-thermal nature and are associated with the emission of molecules of volatile substances in the gas phase and the products of their oxidation. With an increase in the laser pulse energy density H, a thermal glow of the surface of larger coal particles is observed, which is described by the Planck formula at T = 3100 K. When H = Hcr (2) is reached, the surface of the coal particles is ignited during the action of the laser pulse. Contributions to the spectra are the glow of the surface of coal particles, emitted carbon particles, and the glow associated with the emission of excited molecules H2, H2O, CO2. With an increase in H> Hcr (2), the processes leading to the glow of coal particles during a laser pulse are similar to those described above for Hcr (2), but the glow intensity increases

Microstructures of Luminescent nc-Si by Excimer Laser Annealing of a-Si:H

1996 ◽  
Vol 452 ◽  
Author(s):  
Xinfan Huang ◽  
Wei Wu ◽  
Honghui Shen ◽  
Wei Li ◽  
Xiaoyuan Chen ◽  
...  
Keyword(s):  
Energy Density ◽  
Pulse Energy ◽  
Laser Annealing ◽  
Laser Wavelength ◽  
Pulse Number ◽  
Excimer Laser Annealing ◽  
Pulse Energy Density ◽  
Transmission Electron ◽  
Ion Laser ◽  
Si Films

AbstractWe have reported for the first time on visible photoluminescence (PL) in crystallized a-Si:H/a-SiNx:H multilayer structures by CW Ar ion laser annealing treatments. In this paper we present new results on visible PL from crystallized a-Si:H by using KrF excimer pulse laser (wavelength 248 nm) irradiating treatments. The transmission electron microscopy and Raman scattering studies reveal the microstructures of crystallized Si films, which depend on the pulse number and the pulse energy density of KrF laser. When the laser pulse energy density is higher than 520 mJ/cm2, the nanosized Si crystallites (nc-Si) can be formed from a-Si:H layers with a thickness of 100 nm and strong PL with a peak wavelength of 610 nm has been observed at room temperature.

Pulsed Laser Melting of Graphite

1985 ◽  
Vol 51 ◽  
Author(s):  
G. Braunstein ◽  
J. Steinbeck ◽  
M. S. Dresselhaus ◽  
G. Dresselhaus ◽  
B. S. Elman ◽  
...  
Keyword(s):  
Energy Density ◽  
Laser Pulse ◽  
Crystalline Structure ◽  
Pulse Energy ◽  
Laser Pulse Energy ◽  
Pulsed Laser ◽  
Laser Melting ◽  
Liquid Carbon ◽  
Pulse Energy Density ◽  
Ion Implanted

ABSTRACTExperimental evidence for laser melting of graphite, by irradiation with 30ns pulses from a ruby laser, is presented. RBS-channeling analysis, Raman scattering and TEM measurements reveal that the surface of graphite melts at a threshold energy density of about 0.6 J/cm2. For laser pulse energy densities above 0.6 J/cm2, the melt front penetration depth increases nearly linearly with increasing energy density. An intense emission of carbon particles during and after irradiation is observed. The thickness of the carbon layer removed in this process also increases nearly linearly with increasing pulse fluence. A dramatic redistribution of ion implanted impurities is also observed. Furthermore, the crystalline structure of the resolidified material is shown to depend on the energy density of the laser pulse. In order to explain these phenomena, a model for laser melting of graphite at high temperatures to form liquid carbon has been developed in which a free electron gas approximation is used to describe the properties of liquid carbon. The model is solved numerically to give the time and depth dependences of the temperature as a function of the laser pulse energy density. Very good agreement is found between the observed melt depth dependence on laser pulse energy density, as determined by RBS-channeling, and the model calculations. The redistribution of ion implanted impurities and the modification of the crystalline structure, caused by the pulsed laser irradiation, are also consistent with the model and permit the determination, for the first time, of interfacial segregation coefficients for impurities in liquid carbon. The model also predicts that liquid carbon at low pressure (p < 1 kbar) has metallic properties.

Influence of Laser Radiation on Movement of Dislocations in Silicon Single Crystals

2021 ◽  
Vol 410 ◽  
pp. 742-747
Author(s):  
Alexander A. Solovyev ◽  
Vladislav V. Rybin
Keyword(s):  
Laser Radiation ◽  
Energy Density ◽  
Laser Pulse ◽  
Pulse Energy ◽  
Acoustic Waves ◽  
Surface Defects ◽  
Linear Defects ◽  
Semiconductor Crystals ◽  
Micro Cracks ◽  
P Type

The behavior of linear defects in n-and p-type silicon, generated by laser radiation is studied for pulse energy density 417 – 1083 mJ/cm2. The features of the nondestructive and destructive effects of the laser pulse on the surface defects formation of the semiconductor crystals are revealed. The formation and movement of dislocations in the crater region and the development of micro cracks, accompanied by acoustic waves are revealed.

Experimental Investigation on Femtosecond Laser Ablation of Polycarbonate

2013 ◽  
Vol 652-654 ◽  
pp. 2359-2362
Author(s):  
Li Tao Qi ◽  
Jin Ping Hu
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Laser Pulse ◽  
Femtosecond Laser ◽  
Pulse Energy ◽  
Laser Pulse Energy ◽  
Morphological Changes ◽  
Femtosecond Laser Ablation ◽  
Experimental Investigations ◽  
Scanning Electron

In this paper, experimental investigations on femtosecond laser (pulse duration:164 fs, wavelength:780 nm) micromachining of polycarbonate have been carried out in air. The lateral and vertical machining precision was evaluated by scanning electron microscopy and profilometer. The morphological changes were observed by scanning electron microscopy. The ablation mechanism varied with the laser pulse energy was discussed. The diameter and depth of the ablated crated are influenced by the laser pulse energy and the number of laser pulses. The relation between the diameter and ablation depth of the crater and the key parameters of femtosecond laser is obtained. Femtosecond laser micromachining of polycarbonate have a potential application of the fabrication of polycarbonate-based devices.

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