Georgii A. Shafeev

Laser writing of nanostructures on bulk Al via its ablation in liquids

Experimental results are presented on the formation of self-organized nanostructures (NSs) on a bulk Al target under its ablation in liquids--water and ethanol--with short laser pulses from 180 femtoseconds (fs) through 350 picoseconds (ps). NSs are characterized by atomic force microscopy, field emission scanning electron microscopy, optical absorption spectroscopy and x-ray diffraction. The period of NSs does not depend on the laser wavelength used from 248 through 800 nm and is approximately 200 nm. NSs on Al show the characteristic absorption peak in the near UV which has been attributed to plasmon oscillation of electrons. The wings of this peak, extending to the visible, lead to a distinct yellow coloration of the processed Al surface. Ultrafast laser structuring of bulk aluminum in liquids may be potentially a promising technique for efficient production of nanosized aluminum.

UNCONGRUENT LASER ABLATION AND ELECTROLESS METALLIZATION OF SIC

Experimental results on the ablation of a SiC single crystal in air under irradiation with a XeCl excimer laser beam are presented. XPS analysis reveals the Si enrichment of the ablated areas under an energy density of the laser beam of 1 to 3.5 J/cm2 and the formation of SiOx in the ablated areas. The nonstoichiometric ablation of SiC allows one to activate selectively the SiC surface for metal deposition from an electroless plating solution. Both Ni and Cu deposits show a good adherence to the SiC surface (up to 0.5 N/mm2). Similar results are observed with SiC ceramics with a better adherence of the electroless metal deposit. The adherence of the deposit to the ablated SiC samples increases upon HF treatment.

Laser activation of diamond surface for electroless metal plating

Selective area electroless nickel and copper deposition onto the surface of diamond single crystals and polycrystalline diamond films has been realized. Three methods of laser‐assisted activation of diamond surface were applied: (i) prenucleation of diamond surface with a thin layer of palladium catalyst via laser‐induced decomposition of a palladium acetyl‐acetonate [Pd(acac)2] solid film; (ii) deposition of palladium by means of the decomposition of Pd(acac)2 dissolved in dimethylformamide; (iii) laser‐induced damage of diamond surface.

Kinetics of Laser-Induced Au Pyrolytic Deposition from the Liquid Phase

Kinetics of Au pyrolytic deposition from organic solutions of triphenyl phosphine complexes induced by a copper-vapor laser beam is studied experimentally. Activation energies Ta and pre-exponential factors are determined for 7 different Au complexes. Measured Ta values range from 1800 K to 9400 K. The average temperature of the GaAs wafer is found to be 70° C for a laser beam power of 10 mW.

Deposition of diamond-like films upon laser irradiation of the interface of a transparent substrate with liquid aromatic hydrocarbons

Abstract Amorphous diamond films are deposited on transparent substrates upon exposure of its interface with liquid hydrocarbons (C6H5CH3, C6H6, and C6H5CH(CH3)2) to pulsed visible radiation of a Cu vapor laser (λ=510.6 nm). The X-ray Auger electron spectroscopy (XAES), reflection high energy electron diffraction (RHEED), scanning electron microscopy (SEM), profilometry, optical spectroscopy, and Raman analysis at λ=632.8 nm excitation wavelength are employed to characterize the deposited films. The sp3 fraction in deposited films amounts to 60–70% and depends on the precursor. The films show excellent adherence, are transparent in the visible and have microhardness of 50–70 GPa, as measured with a nanoindentor. The sp3 bond fraction in deposited films increases with addition to the liquid hydrocarbon a suspension of diamond nanoparticles.

Laser-assisted nickel deposition onto synthetic diamonds

Abstract Electroless nickel (nickel-phosphorus alloy) plating onto a diamond surface prenucleated by a thin palladium layer via laser-induced decomposition of palladium acetyl-acetonate film was studied. The results on spatial selectivity and adherence of the nickel deposits are reported.

Periodic ripples produced by a scanning beam of a femtosecond Ti:sapphire laser

The formation of periodic ripples is reported under exposure in air of several solids (Ge, GaAs, W, steel, etc.) to a scanning beam of a femtosecond Ti:sapphire laser operating at wavelength λ = 810 nm. Atomic Force Microscope (AFM) and Scanning Electron Microscope (SEM) characterization shows that the period of ripples at normal incidence of laser radiation lies in a sub-λ domain and depends on the nature of the solid. Ripples are oriented perpendicular to the plane of polarization of the laser beam. Their period is different under ablation of a solid in a liquid environment at otherwise equal conditions. The results are interpreted as an interference of the incident laser radiation with a surface electromagnetic wave induced in the solid. The examples are presented of sub-μm structures generated by intersection of several ripple arrays.