Growth of heteroepitaxial ZnO thin films by femtosecond pulsed-laser deposition

Abstract

ZnO thin films have been grown on various substrates by femtosecond pulsed-laser deposition. According to optical microscopy and atomic force microscopy analyses, the production of droplets is not significant using femtosecond pulses. Smooth, dense, stoichiometric, crystalline, and textured hexagonal ZnO films are epitaxially grown on (0001) sapphire at 700 °C with an in-plane epitaxial relationship corresponding to a 30° rotation of the ZnO basal plane with respect to the sapphire. Nevertheless, channeling experiments and rocking curve measurements show that the crystalline quality is not as good as that obtained with nanosecond pulses.

Growth and magnetic characterization of Co nanoparticles obtained by femtosecond pulsed laser deposition

“…[6][7][8][9][10][11][12][13][14][15] In spite of this effort, however, very little has been done on the nature and properties of the material obtained from this ablation process once it is deposited on a substrate surface, either in the form of a continuous film or as nanoparticles. Deposition of continuous thin films using fs lasers has been successful in the case of oxides or nitrides, [16][17][18][19][20][21] with ablation in the presence of a gas in the deposition chamber that reacts or interacts to some extent with the ejected material, leading to the growth of a continuous film on the substrate.…”

Production of gas phase zinc oxide nanoclusters by pulsed laser ablation

“…Several physical and chemical methods like molecularbeam epitaxy [1], chemical vapor deposition [5], sputtering [6] have been successfully applied for ZnO film synthesis. The technique of nanosecond [2,3,4,7,8,9] and femtosecond [10] pulsed laser ablation (PLA) has been also widely used to produce both epitaxial and nanostructured ZnO films of high optical quality. The synthesis of nanocrystalline films is usually performed in an ambient gas whose pressure should be high enough, firstly, to confine the plasma created after laser ablation in order to favor the collisions and chemical reactions in the laser induced plume and, secondly, to induce a rapid cooling of the plasma to favor the condensation of the nanoclusters in gas phase [11].…”

Mg-based photocathodes prepared by ns, ps and fs PLD for the production of high brightness electron beams

“…The particulates present on film surface have spherical shape, with diameters of about 10 mm. This morphology may be due to the fact that the material is heated mainly by thermal diffusion and the ablation is accompanied by the expulsion of fused material before resolidification of target surface takes place [6]. In fact, in long laser pulses regime, the laser beam energy is absorbed in a surface layer whose thickness is of the order of the optical penetration depth, l s = 1/a, where a is the absorption coefficient for a fixed wavelength.…”