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Laser-Induced Self-Organization of Nano- and Micro-Structures of Surface Relief via Defect-Deformational Instabilitiesстатья
- Автор: Emel'yanov V.I.
- Сборник: PHASE TRANSITIONS INDUCED BY SHORT LASER PULSES, GEORGY A. SHAFEEV EDITOR,
- Год издания: 2009
- Место издания: Nova Science Publishers, Inc New York
- Первая страница: 183
- Последняя страница: 228
- DOI: ISBN: 978-1-60741-590-9
- Аннотация: The Defect-Deformational (DD) approach to the problem of laser-induced formation of nano-and microstructures of surface relief in semiconductors and metals is presented. It is demonstrated that laser or ion beam-created stressed flat surface layer with point defects exhibits a threshold (in respect to the defect concentration or mechanical stress) transition to a spatially periodic bent state with a simultaneous formation of the periodic defect piles up at the extrema of the spontaneously emerging surface relief (DD grating). The layer deformation corresponds to the displacements in a static bending quasi-Lamb wave and the deformation of the underlying elastic continuum corresponds to the displacements in the static quasi-Rayleigh wave. It is shown that not far from the instability threshold the DD selforganization is described by the closed nonlinear equation of Kuramoto-Sivashinsky type. More general analysis simultaneously involving the nonlocal character of the defect interaction with the lattice atoms and both (normal and lateral) defect-induced forces that cause the bending of the surface layer yields two maxima on the curve of the 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 irradiation of semiconductors. Based on the results obtained, we propose a cooperative DD mechanism for the formation of an ensemble of the nanoparticle nucleation centers above the critical levels of the stress or the defect concentration. A new approach to the calculation of a bimodal distribution function of the nanoparticles with respect to their size is developed adequate to the DD mechanism of nucleation which expresses the distribution function through the growth rate. Nonlinear three DD gratings interactions are shown to lead to generation of second harmonic of surface relief and mixing of DD gratings wave vectors. The developed theory of DD instability of the surface layer is applied for the interpretation from the unified viewpoint оf experimental results obtained in studies of formation of ordered nano and microstructures on the surface of semiconductors under the action of laser pulses with different duration and fluencies. The DD structures symmetry and its evolution with increase of laser fluence and magnitude of external anisotropic stress are discussed. Similarities with formation of nanostructures under ion beam irradiation are also discussed in the framework of DD instability theory.
- Добавил в систему: Емельянов Владимир Ильич