Evidence for the physical basis and universality of the elimination of particulates using dual-laser ablation. I. Dynamic time-resolved target melt studies, and film growth of Y2O3 and ZnO

Abstract

Articles you may be interested inNanometric multiscale rough Zn-ZnO superhydrophobic thin films: Self-diffusion of zinc and effect of UV irradiation Evidence for the physical basis and universality of the elimination of particulates using dual-laser ablation. II. Dynamic time-resolved target reflectivity of metals and film growth of ZnThe application of a dual-laser ablation process, incorporating the addition of a synchronized CO 2 laser to the traditional excimer ͑KrF͒ laser used for the ablation of targets in thin film deposition, has been previously demonstrated to be effective in the elimination of particulates in films of Y 2 O 3 ͓J. Vac. Sci. Technol. A 13, 1171 ͑1995͔͒. It has been hypothesized that the efficacy of particulate removal is related to phase transformation from the solid to liquid phase prior to excimer laser ablation of the target material. In this series of two articles we present direct physical evidence of the dynamics of the phase transformation occurring on the target surface and its effect on the morphology of film growth. Pump-probe experiments have been conducted using the CO 2 laser to probe the dynamic reflectivity of the target surface on the nanosecond timescale. These experiments were conducted for a range of materials spanning a wide range of thermal conductivity including a low thermal conductivity insulator (Y 2 O 3 ), and a sublimating oxide ͑ZnO͒, as well as a high thermal conductivity metal ͑Zn͒ to assess the universal applicability of the results. In this article ͑Part I͒ the results of these dynamic reflectivity experiments are correlated with previously reported particulate-free deposition of thin films of Y 2 O 3 . Similar experiments are conducted for ZnO. In both cases, the reflectivity measurements yielded times for the onset of melt at a variety of CO 2 laser fluences. Synchronization of the KrF laser to coincide with the onset of melt resulted in particulate-free film growth. The effect of mistiming on the quality of the deposited film is presented for ZnO.

Double pulse laser ablation and plasma: Laser induced breakdown spectroscopy signal enhancement

“…Experiments [53] demonstrate that the use of double laser pulses (femtosecond laser) separated by several nanoseconds increases the lifetime of the plasma channel (plasma volume with low electrical resistance formed by a laser spark) generated in air by 5 times in comparison with the use of the single pulse equivalent mode. 9) Particles, nanoparticle generation [11,35,[55][56][57][58]. Scuderi et al [11] found a large drop in the emission signal from nanoparticles at delays between fs-pulses of 0.8 < Δt < 1 ns (Ti sample, 10 12 -10 14 W/cm 2 ).…”

“…Mukherjee et al [55] and Witanachchi and Mukherjee [56] suggested the use of dual laser ablation for the elimination of particulates. The experiments demonstrated that control of the interpulse delay and laser fluences is essential for successful particulate removal.…”

“…The first pulse is used to ablate the material, whereas the second pulse interacts with the plume of the first pulse and produces a finer aerosol. Mukherjee et al [55] and Witanachchi and Mukherjee [56] suggested dual laser ablation for the elimination of particulates with laser machining processes. The splashing or particulate deposition in the growth of thin films is undesirable in the fabrication of electronic or optical devices.…”

“…The second pulse couples effectively to the liquid layer, leading to total vaporization of the melted front and leaves behind a smooth structure without a residual cast. The velocity of melt propagation, measured by Mukherjee et al [55], was in the range from 5 to 35 km/s and linearly dependent on the laser fluence (3-15 J/cm 2 , ZnO).…”

Growth and Characterization of Germanium-Based Type I Clathrate Thin Films Deposited by Pulsed Laser Ablation

“…In this paper we report the first results on the growth and structural characterization of germaniumbased clathrate thin films of Ba 8 Ga 16 Ge 30 using pulsed laser deposition. One of the main advantages of laser ablation for thin film growth is the ability of this process to closely reproduce the target stoichiometry in the deposited film [15][16][17]. Therefore, laser ablation is uniquely suited for the growth of multi-component films from a single composite target such as Ba 8 Ga 16 Ge 30 .…”