Fundamentals of laser-assisted micro- and nanotechnologies

This book covers the state of the art of laser micro- and nanotechnology. The physical fundamentals of different processes and the application are presented. The book deals with different materials like phase change and memory alloys, thin films, polymers etc. New phenomena and mechanisms of laser-matter interaction in nano-domains are explained. This book is helpful for students, postgraduates, engineers and researches working not only in the field of laser microtechnology but also in high-tech industry, like photonics, microelectronics, information technology

Fundamentals of Laser-Assisted Micro- and Nanotechnologies

XVII, 322 p. 145 illus., 49 illus. in color.onlin

Cleavage-Driven Laser Writing in Monocrystalline Diamond

The propagation of graphitization wave through the diamond bulk under multipulse laser irradiation is a largely self-guided process. This fact assists the production of graphitized wires oriented along a laser beam and greatly complicates formation of the structures oriented differently. Here, we develop new approaches to control laser graphitization that should empower the potential of 3D laser microstructuring inside a diamond crystal. Two techniques are investigated: (i) a laser seed damage of crystal with subsequent exposure at a lower laser fluence, thus restricting the propagation of the graphitization wave toward the beam and (ii) formation of a dominant microfracture perpendicular to the laser beam, thus guiding growth of the graphitized thread

Technology Features of Diamond Coating Deposition on a Carbide Tool

The production of carbide tools with polycrystalline diamond coatings, which are used for processing modern carbon composite materials, includes a number of technological techniques that ensure reliable adhesion of the coating to the substrate. This review examines these features of substrate-surface pretreatment to improve adhesion, which includes chemical etching, mechanical hardening, modification by ion beams, plasma treatment and application of buffer layers between the substrate and the coating. This review also discusses the advantages and disadvantages of the most common methods for obtaining polycrystalline diamond coatings using hot filament and deposition of coatings from microwave plasma

Technology Features of Diamond Coating Deposition on a Carbide Tool

The production of carbide tools with polycrystalline diamond coatings, which are used for processing modern carbon composite materials, includes a number of technological techniques that ensure reliable adhesion of the coating to the substrate. This review examines these features of substrate-surface pretreatment to improve adhesion, which includes chemical etching, mechanical hardening, modification by ion beams, plasma treatment and application of buffer layers between the substrate and the coating. This review also discusses the advantages and disadvantages of the most common methods for obtaining polycrystalline diamond coatings using hot filament and deposition of coatings from microwave plasma

Diamond composite with embedded YAG:Ce nanoparticles as a source of fast X-ray luminescence in the visible and near-IR range

The diamond composite materials with embedded yttrium-aluminum garnet doped with cerium (YAG:Ce) nanoparticles have been produced by microwave plasma-assisted chemical vapor deposition (CVD). Nanoparticles were synthesized by co-precipitation from an aqueous solution while CVD diamond served as the transparent matrix with high thermal conductivity, hardness, and resistivity to radiation damage. The composite films show high-intensity X-ray luminescence (XRL) with a broad band peaking around the wavelength of 550 nm (5d → 4f transition in Ce$^{3+}$ ion), and a narrow peak of silicon-vacancy (Si–V) centers at 738 nm. The characteristic decay time was measured at $τ_{Ce}$ < 50 ns for cerium emission and at $τ_{SiV}$∼1 ns for Si–V centers. Excitation spectra of both luminescence types measured near yttrium K-edge (17.1 keV) show a strong correlation, attributed to the excitation of Si–V luminescence by photoelectrons ejected from YAG:Ce nanoparticles. The discovered phenomenon suggests a new way to control X-ray visualization by luminescent diamond composites for fast X-ray detectors and screens

Diamond Detector With Laser-Formed Buried Graphitic Electrodes: Micron-Scale Mapping of Stress and Charge Collection Efficiency

The paper reports the micron-scale investigation1 of an all-carbon detector based on synthetic single crystal2 CVD-diamond having an array of cylindrical graphitic buried-3 contacts, about 20 µm in diameter each, connected at the4 front side by superficial graphitic strips. To induce diamond-5 to-graphite transformation on both detector surface and bulk6 volume, direct-laser-writing technique was used. Laser-treatment7 parameters and cell shape have been chosen to minimize the over-8 lapping of laser-induced stressed volumes. Optical microscopy9 with crossed polarizers highlighted the presence of an optical10 anisotropy of the treated material surrounding the embedded11 graphitized columns, and non-uniform stress in the buried12 zones being confirmed with a confocal Raman spectroscopy13 mapping. Dark current-voltage characterization highlights the14 presence of a field-assisted detrapping transport mainly related15 to highly-stresses regions surrounding buried columns, as well as16 superficial graphitized strips edges, where electric field strength17 is more intense, too. Notwithstanding the strain and electronic-18 active defects, the detector demonstrated a good charge collection19 produced by 3.0 and 4.5 MeV protons impinging the diamond,20 as well as those generated by MeV β-particles emitted by 90Sr21 source. Indeed, the mapping of charge collection efficiency with22 Ion Beam Induced Charge technique displayed that only a few23 micrometers thick radial region surrounding graphitic electrodes24 has a reduced efficiency, while most of the device volume25 preserves good detection properties with a charge collection26 efficiency around 90% at 60 V of biasing. Moreover, a charge27 collection efficiency of 96% was estimated under MeV electrons28 irradiation, indicatingthe good detection activity along theburied29 columns dept

CVD synthesis of multi-layered polycrystalline diamond films with reduced roughness using time-limited injections of N2 gas

Multi-layered polycrystalline diamond (PCD) films were synthesized using microwave plasma-assisted chemical vapor deposition (CVD) with periodical addition (injections) of N2 gas to the standard CH4-H2 gas mixture. The aim of such an approach was to reduce the roughness of the films while preserving the overall high quality and phase purity of the PCD material. The thicknesses of the films were in the range of 5 to 51 μm, while the number of layers was from 1 to 15. The introduction of even the smallest amount of nitrogen leads to a significant (more than 2-fold) increase in the growth rate of PCD films. Optimized injection regimes allowed the reduction of the relative roughness (Sq/thickness) of the PCD films by more than 3 times in comparison with standard microcrystalline diamond film grown under similar conditions without N2 addition. The proposed method of periodic injection of N2 during growth restricted the formation of continuous NCD layers, which improved the overall sp3/sp2 ratio in comparison with standard multi-layered MCD/NCD materials. The obtained multi-layered PCD materials with reduced roughness may be used for the formation of protective and hard covers, optical coatings, electrochemical and thermal management applications. Prime novelty statement The multi-layered PCD films were synthesized in a microwave plasma CVD in regimes with short-term periodic N2 injections in CH4-H2 process gas; the average growth rate is doubled owing to the pulsed nitrogen injection, while the surface roughness is reduced by more than 3 times in comparison with a standard (no N2 injection) microcrystalline film