Morphology and structure of Pb thin films grown on Si(111) by pulsed laser deposition

Abstract

Pulsed laser deposition (PLD) is a versatile thin film deposition technique in which high powered laser beam interacts with a target material inside an ultrahigh vacuum chamber. Highly energetic particles such as electrons, atoms, protons, and ions generate a plasma plume that directed towards a substrate material where recondenses form a thin film. PLD is an effective and reliable method to create varieties of thin films such as metal, polymer, and ceramic for many technologically essential applications. In this study, thin Pb films were grown by pulsed laser deposition on Si (111) at various laser fluences, pulse wavelengths, deposition times, and substrate temperatures. Nanosecond pulsed Nd: YAG laser with 1064 nm fundamental wavelength, 10 Hz frequency, and 5 ns pulse duration used to ablate the 99.99% pure Pb material. Scanning electron microscopy (SEM) and ex situ atomic force microscopy (AFM) were used to probe the surface morphology and structure. At room temperature, increasing the laser fluence and/or the pulse wavelength triggers the transformation from the "worm"-like interconnected islands to granular, separated islands. Increasing the substrate temperature to slightly below the Pb melting temperature results in the formation of large, nearly spherical non-wetting islands. Additionally, ultrathin Pb (111) films were grown at room temperature, which resulted in the appearance of a small number of almost 2D islands due vii to the emerging quantum size effect. Our results show that pulsed laser deposition can be used effectively for the controlled growth of Pb thin films.

Bioactivity and Mechanical Properties of Hydroxyapatite on Ti6Al4V and Si(100) Surfaces by Pulsed Laser Deposition

“…With temperature increase, the film became textured, and for a substrate temperature of 650−850 • C, a mix of cubic NbN and hexagonal phases was formed, and the surface roughness of the NbNx films increased as the temperature was raised from 450 • C to 850 • C. For Pb films, it was shown that when the substrate temperature was raised from RT to 300 • C, the film growth mechanism changed from Volmer-Weber to cluster formation mode. When the temperature was raised to values close to the melting temperature of Pb, the Ostwald ripening effect was observed [67]. In our case, the melting temperature of HA was far from the substrate temperature range; however, the results suggest that the variations in substrate temperature affected the nucleation-growth process, allowing smaller particles to conglomerate and possibly form larger crystals.…”

Synthesis and Characterization of a Zirconium (Zr) Thin Film on Si(100) via Pulsed Laser Deposition

“…Among the different deposition methods, the pulsed laser deposition (PLD) technique is considered a highly versatile technique for a growing number of thin film applications [5][6][7][8][9][10][11][12]. PLD uses high-energy laser pulses to vaporize the surface of a solid target inside a vacuum chamber and condenses the vapor on a substrate to form a film.…”