Publication Date

Spring 2020

Advisor(s) - Committee Chair

Ali Oguz Er (Director), Ivan Novikov, and Mikhail Khenner

Degree Program

Department of Physics and Astronomy

Degree Type

Master of Science

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 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.

Disciplines

Engineering Science and Materials | Physical Sciences and Mathematics | Semiconductor and Optical Materials

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