Modeling of nonequilibrium melting and solidification in laser-irradiated materials

Wood, R. F.; Geist, G.A.

doi:10.1103/physrevb.34.2606

Cited by 153 publications

(48 citation statements)

References 26 publications

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“…The residual Si acts as a seed in the solidification process and forms a large Si grain. 16 Finally, poly-Si grains are reformed at the same positions as the previous configurations. However, if the laser energy is insufficient, the solid Si is only melted partially and growth occurs over the whole liquid-solid interface.…”

Section: A Melting Front Simulations For Ripple Spacing and Polarizamentioning

confidence: 99%

“…There are numerical reports on laser annealing simulations that couple the heat transfer equation with the laser source and material phase change. [13][14][15][16] For heat dissipation, we used the model suggested by Ref. 16 which considers the various aspects of the complex melting and solidification process including nucleation events.…”

Section: Introductionmentioning

confidence: 99%

“…[13][14][15][16] For heat dissipation, we used the model suggested by Ref. 16 which considers the various aspects of the complex melting and solidification process including nucleation events. 6,7,16 In our simulations, we allowed the surface roughness during melt to decay with a relaxation time, τ,…”

Section: Introductionmentioning

confidence: 99%

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Laser pulse shape dependence of poly-Si crystallization

2017

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Poly-Si crystallization mechanism is examined by conducting numerical simulations, combining the thermal diffusion equation with a rigorous coupled wave analysis method. The ripples at the boundary of poly-Si grains are modeled as a grating surface structure. Under laser beam irradiation, the melting front profiles are accurately analyzed by including surface diffraction, polarization of the laser, and laser energy density. For two different lasers, XeCl excimer laser (λ = 308 nm) and Yb:YAG solid state laser (λ= 343 nm), the energy density range at which poly-Si grains are gradually ordered was determined. Furthermore, the energy density window of the Yb:YAG laser is found to be four times larger than that of XeCl laser. On the other hand, the Yb:YAG laser may produce amorphous-Si phase after completing the crystallization process. It is suggested that this amorphous-Si phase could be avoided, if a double pulse laser is used.

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Section: A Melting Front Simulations For Ripple Spacing and Polarizamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Laser pulse shape dependence of poly-Si crystallization

2017

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“…Consequently, there is a need for the development of 2D models to be used in explaining such features. In previous work, a one-dimensional model and a computer program (called LASER8) were developed to deal with various pulsed-laser annealing phenomena [5,6]. Recently this program was incorporated into a larger laser ablation 171 program.…”

Section: Introductionmentioning

confidence: 99%

“…On melting, Si becomes metallic with the reflectivity R, at k = 633 nm increasing by 7 5 8 and the electrical conductivity by a factor of 20. Therefore, nanosecond-pulsed-laser melting of a-Si at an energy density (El) just above the threshold for melting results in a highly undercooled liquid whose formation and subsequent behavior can be studied directly by time-resolved electrical [9,10] and optical [ 1 11 measurements. In the modeling underlying the LASER8 program, a state array concept was introduced which allows a wide variety of physical effects to be simulated as an adjunct to the heat flow and phase change calculations [5,6]. The state array essentially specifies a number of conditions which the material in a given finite-difference (FD) cell and its neighboring cells must satisfy in order for a phase transition and/or a change in microstructure to occur.…”

Section: Introductionmentioning

confidence: 99%

Modeling and Simulation of Pulsed Laser annealing and ablation of Solid Materials

Liu

Wood

1995

MRS Proc.

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Several different aspects of laser annealing and laser ablation have indicated the need for two-dimensional (2-D) modeling of heat transfer and phase-change effects. We have in mind particularly the laser-induced formation and propagation of buried liquid layers for the case of a-Si on a crystalline silicon substrate, questions related to the early stages of the laser ablation of insulators such as MgO where it is believed that the absorption of the laser radiation occurs at localized but extended regions of high concentrations of defects, and the ejection of particulate material during laser ablation. To deal with these phenomena, a 1-D computational model originally developed for laser annealing has been extended to two-dimensions. the 2-D modeling examines the heat flow and phase changes associated with localized heat sources embedded in a planar material. Concepts such as the state diagram and state array used in the 1-D work have been extended to 2-D and refined. the 2-D program has been rewritten for massively parallel machines such as the intel Paragons in ORNL's Center for Computational Sciences, thus allowing larger and more accurate calculations for complex systems to be carried out in reasonable times.

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Lateral Grain Growth during the Laser Interference Crystallization of a-Si

Aichmayr

Toet

Mulato

et al. 1998

phys. stat. sol. (a)

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We used laser interference (LIC), a combination of pulsed laser crystallization and holography, to fabricate polycrystalline silicon lines in an amorphous silicon (a‐Si) film. Under appropriate conditions, the grains in the lines reach in‐plane dimensions appreciably larger than the thickness of the initial a‐Si film (up to 1.7 μm for a 300 nm a‐Si film). Atomic force and transmission electron microscopy indicate that these large grains result from the lateral solidification of the silicon lines melted by the laser pulse. The lateral growth is well reproduced by simulations of the LIC dynamics by means of a two‐dimensional melting and solidification model.

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Modeling of nonequilibrium melting and solidification in laser-irradiated materials

Cited by 153 publications

References 26 publications

Laser pulse shape dependence of poly-Si crystallization

Laser pulse shape dependence of poly-Si crystallization

Modeling and Simulation of Pulsed Laser annealing and ablation of Solid Materials

Lateral Grain Growth during the Laser Interference Crystallization of a-Si

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