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Title:Photoemission Studies of the Electronic Structure and Properties of Thin Lead Films; nanoscale; atomically; pb films; particle in a box; ARPES; vacume-film; photoelectron;
Author(s):Upton, Mary Hope
Department / Program:Physics
electronic structure
thin lead
thin lead films
beam epitaxy
schottky barrier
angle calibration
quantum well
angular resolution
energy resolution
subsequent confirmation
thermal stability
Abstract:This dissertation examines the properties of nanoscale, atomically uniform Pb films grown on Si. We describe a method for growing atomically uniform thin Pb films on Si and various properties of the films. This is the second system of atomically uniform films grown, and the first metal on semiconductor system. (The first system was a metal-on-metal system.) The electrons in the Pb are in a particle-in-a-box-like potential. In two dimensions, transverse to the film, they are in an effectively in¯nite crystal. Normal to the film, the electrons in the films are confined in the film by the vacuum-film potential barrier on one side and by the film-substrate barrier on the other. The states from this confinement are observable and called quantum well states. We studied the properties of these states to learn the electronic structure of the film. The Pb films are studied with angle-resolved photoelectron spectroscopy (ARPES). In ARPES, a sample is illuminated with photons, and electrons excited by the photons are emitted from the sample. By measuring the momentum of the escaping electrons, the electronic structure of the sample can be determined. The quantum well states experience different types of confinement depending on whether they are above or below the Si valence band edge. They show large oscillations in the thermal stability. Adding 1 ML to a film can make it stable to an additional 50±C. The effective masses of the subbands also show some unusual features.
Issue Date:2005
Genre:Dissertation / Thesis
Rights Information:2005 Upton ©
Date Available in IDEALS:2012-11-27

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