Rose Deformation Patterns in Thin Films Irradiated by Focused Laser Beams

Lauzeral, J.; Walgraef, Daniel; Ghoniem, Nasr M.

doi:10.1103/physrevlett.79.2706

Cited by 14 publications

(6 citation statements)

References 7 publications

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“…Though, the action of laser pulses on surfaces of crystalline solids may cause the generation of structural defects of the type of vacancies and interstices in the surface layer [5][6][7][8][9], the concentration of which can change during a laser pulse by several orders as against the initial one and can reach the values of lO18lO2O cm-3. So surface oxidation in this case presents a rather complicated process of oxygen diffusion in the surface layer of the material, where the temperature and defect concentration are quickly varied with time.…”

Section: Introductionmentioning

confidence: 99%

Abnormal increase of time of oxygen diffusion with oxidation of silicon surface under action of powerful laser pulses

2000

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Section: Introductionmentioning

confidence: 99%

Abnormal increase of time of oxygen diffusion with oxidation of silicon surface under action of powerful laser pulses

2000

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“…Since the film is thin, and only small adhesion forces exist on the bottom surface, then all transverse stress tensor components are nearly zero ͑plane stress conditions͒. Therefore, it can be shown 13 that the nonzero components of the strain tensor are…”

Section: B Strain Tensor Componentsmentioning

confidence: 99%

Deformation patterns in thin films under uniform laser irradiation

Walgraef

Ghoniem

Lauzeral³

1997

Phys. Rev. B

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The mechanical behavior of thin films subjected to laser irradiation is described by a dynamical model that is based on coupled evolution equations for the deformation and vacancy density fields. Lattice vacancies are generated in a thin layer as a result of shallow absorption of electromagnetic laser radiation. The strain field associated with lattice dilatation due to vacancies is shown to couple with bending and stretching mechanical deformation fields. The dynamical model developed here is an extension of the work of Emel'yanov in two respects: ͑1͒ the coupling between the diffusion and mechanical deformation fields is rigorously developed with additional cross-field contributions; ͑2͒ new equations for reduced dynamics are derived from this model, and are used to analyze the physical conditions for the onset of a deformational instability. For a given material, the threshold for this instability is correlated mainly with laser power. We also show that, although the instability threshold and critical wavelengths are given by the linear part of the dynamics, the selection and type of deformation patterns induced by this instability require a nonlinear formulation. Both numerical and analytical analysis are performed here. According to the relative importance of nonlinearities arising from the defect or from the bending dynamics, square or hexagonal planforms are shown to be selected. Furthermore, it appears that one-dimensional gratings are always unstable in isotropic systems. The results for square patterns are consistent with experimental observations, while those for hexagonal and one-dimensional gratings show the importance of anisotropies on their final selection. ͓S0163-1829͑97͒03847-2͔

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“…Pattern formation under extended and focused irradiation has already been described elsewhere, in the framework of this model. 9,20,21 However, in these papers, defect generation and transport have been considered as isotropic, which is not applicable for crystals with strong covalent bonding. For example, deformation patterns formed on Si surfaces depend on the laser field orientation in relation to crystallographic axes.…”

Section: Introductionmentioning

confidence: 98%

Effect of crystal anisotropy and adhesive forces on laser induced deformation patterns in covalently bonded thin films

Walgraef¹,

Ghoniem

2002

Phys. Rev. B

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The effect of crystal structure on laser induced deformation patterns in thin films and surfaces is analyzed within the framework of a dynamical model for the coupled evolution of defect densities and deformation fields. In crystals with covalent bonding, such as Si and SiC, preferential bond breaking may occur, as a result of the relative orientation of the laser electric field and crystallographic axes. We extend here our theoretical framework to incorporate the effects of anisotropic defect diffusion, and the influence of film-substrate adhesion on deformation pattern selection and stability of thin films subjected to laser beams. We also compare theoretical predictions to experimental observations on single crystal silicon wafer surfaces. Furthermore, it is predicted that the laser induced damage threshold for SiC single crystals can be in excess of 200 J/cm 2 .

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Rose Deformation Patterns in Thin Films Irradiated by Focused Laser Beams

Cited by 14 publications

References 7 publications

Abnormal increase of time of oxygen diffusion with oxidation of silicon surface under action of powerful laser pulses

Abnormal increase of time of oxygen diffusion with oxidation of silicon surface under action of powerful laser pulses

Deformation patterns in thin films under uniform laser irradiation

Effect of crystal anisotropy and adhesive forces on laser induced deformation patterns in covalently bonded thin films

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