E-Locus - Institutional Repository of the University of Crete

Home Search

Results - Details

Search command : Author="Φωτάκης" And Author="Κώστας"

Current Record: 5 of 7

[Add to Basket]

Identifier

000375551

Title

Femtosecond laser micro/nano structuring of solid surfaces : fundamentals and applications

Alternative Title

Μικρο/νανο δόμηση στερεών υλικών με την χρήση femtosecond παλμών λέισερ : βασικές αρχές και εφαρμογές

Author

Μπαρμπέρογλου, Μάριος Ιωάννη

Thesis advisor

Φωτάκης, Κώστας

Reviewer

Στρατάκης, Μανώλης
Λουκάκος, Παναγιώτης
Τσιμπίδης, Γεώργιος
Ρανελά, Ανθή

Abstract

Controlling the interactions of laser beams with matter is crucial for the success and scalability of materials processing applications. The optimal interplay between the laser irradiation and material parameters allows controlled modification of surface properties at different length scales adding a new dimension to materials properties optimization. For a given wavelength, the laser pulse duration is a critical parameter and processing by ultrashort (i.e. sub-picosecond) laser pulses opens new exciting possibilities. In comparison to ps and longer laser pulses, ultrafast laser processing provides two major advantages: (a) a net decrease of the ablation threshold for identical laser wavelength and focusing conditions and (b) an important decrease of the heat affected zone that can greatly reduce the extent of collateral damage to the surrounding area,[2] allowing the production of sub-wavelength nanostructures. Such characteristics are due to the rapid energy deposition inside the target material and the subsequent non-linear processes induced at the focal point. Experimentally, it has been shown that the internal thermalization of the electron distribution following excitation by a femtosecond (fs) laser pulse takes place within one ps. Thermalization between the electron subsystem and the lattice is usually longer and is of the order of several ps, depending on the electron–phonon coupling strength. Thus, ultrafast laser excitation generates a hot electron gas which is in a highly non-equilibrium state with the lattice. As a consequence, direct irradiation of materials by ultrafast laser pulses induces modifications leading to complex micro- and nano- scale surface features, which are often found to have unique properties and cannot be realized by other, non-laser based techniques. Laser micro- and nanostructuring of materials is important in many scientific, technological and biological applications, such as the fabrication of opto- and nanoelectronic devices, information storage systems, control over the mechanical and optical properties of solids, microfluidics and biomedical engineering. In this thesis we present the fabrication, and formation mechanisms of different kinds of micro- and nano- scale structures on the surface of semiconducting and metallic materials fabricated by means of ultrafast laser processing. Two distinct approaches are reviewed including laser surface modification in controlled gas and liquid media respectively. Emphasis will be placed on the exploitation of the materials and structures attained to modern applications for which there is an increasing demand over the previous years. Besides presenting recent advances achieved by these techniques, it will also delineate existing limitations and discuss emerging possibilities and future prospects.

Language

English

Subject

Adhesion

Cell

Culture

Electrowetting

Interaction

Materials

Neurons

Pulse

Ripples