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Mechanisms of laser-induced self-organization of nano-and microstructures of surface relief in air and in liquid environmentстатья
Информация о цитировании статьи получена из
Web of Science,
Scopus
Дата последнего поиска статьи во внешних источниках: 28 ноября 2013 г.
- Автор: Emel’yanov V.I.
- Сборник: In “Laser ablation in liquids: Principles and Applications in Preparation of Nanomaterials”, Chapter 1
- Год издания: 2012
- Место издания: Pan Stanford Publishing Singapore
- Первая страница: 1
- Последняя страница: 110
- Аннотация: A review of fundamental mechanisms of laser-induced formation of nano- and microstructures of surface relief in semiconductors and metals in air and in liquid environment is presented. Two classes of laser-induced surface relief instabilities occurring in solid and in liquid (molten) phases are considered. For a solid phase it is demonstrated that a laser (or ion) beam-created stressed flat isotropic surface layer with laser-generated mobile point defects exhibits a threshold (in respect to the defect concentration) transition to a spatially periodically bent state with a simultaneous formation of the periodic defect piles up at the extrema of the spontaneously emerging surface relief (the defect-deformational (DD) instability). The layer deformation corresponds to the displacements in a static bending quasi-Lamb wave and the deformation of an underlying elastic continuum corresponds to the displacements in a static quasi-Rayleigh wave. It is shown that the DD self-organization is described by the closed isotropic nonlinear DD Kuramoto–Sivashinsky (DDKS) equation. Results of detailed analytical and numerical investigations of the isotropic DDKS equation are presented and compared with experiment. More general analysis simultaneously involving the nonlocal surface strain dependence of the force acting on defects and both (normal and lateral) defect-induced forces that cause the bending of the surface layer yields two maxima on the curve of the DD instability growth rate versus the period of the generated relief. This corresponds to the experimentally observed two scales of the surface relief modulation upon the laser and ion-beam irradiation of semiconductors. Based on the results obtained, a cooperative DD mechanism of the formation of an ensemble of the nanoparticle nucleation centres is proposed. A new approach to the calculation of the experimentally observed bimodal size distribution function of the nanoparticles is developed adequate to the DD mechanism of nucleation that expresses the distribution function through the growth rate. Nonlinear three DD grating interactions are shown to lead to the generation of second harmonic of surface relief and mixing of the DD grating wave vectors. The DD structures’ symmetry and their evolution with increasing laser fluence and magnitude of laser-induced anisotropic stress are considered on the basis of the linear anisotropic DD model and the anisotropic DDKS equation. The developed theory of the DD instability of the surface layer is applied for the interpretation of experimental results obtained in studies of the formation of ordered nano- and microstructures on the surface of semiconductors and metals under the action of laser pulses with different durations and fluencies in air and in liquid confinement. Similarities with the formation of nanostructures under ion-beam irradiation are also discussed in the framework of DD instability theory. On the basis of the DD model, the interpretation of sub-wavelength ripple formation is given. For the molten state a closed nonlinear two-dimensional hydrodynamic Kuramoto–Sivashinsky (HDKS)-type equation for the modulation of the thickness of the laser pulse-induced molten layer is derived. It is shown that in liquid environment, when the temperature gradient at the surface is directed from the surface to the bulk the thermocapillary instability of surface relief arises leading to the formation of surface relief structures with wavelength September 22, 2011 15:50 PSP Book - 9in x 6in 01-Yang-c01 Introduction 3 proportional but an order of magnitude larger than the thickness of the molten layer. Computer simulations of the HDKS equation predict the subsequent formation of lamellar and disordered (quasi-hexagonal) structures of surface relief when the time of irradiation is increased. The obtained results are used for the interpretation of experimental data on the formation of lamellar and quasi-hexagonal surface relief microstructures upon multiple nanosecond pulse laser irradiation of silicon inwater confinement.
- Добавил в систему: Емельянов Владимир Ильич