Tized Phonon Modes And The Electron-phonon Interaction In Metallic Nanowire Structures

Nanotechnology is making revolutionary impact on diverse fields including electronics, optoelectronics, materials science, etc. In recent years, nanomaterials have drawn a great attention due to its special properties in heat, light, electricity, and magnetism, etc.. It becomes possible to realize the metallic nanowire (NW) structures which consist of metal NW embedded in dielectric templates. Metallic NW has important applications in optoelectronic devices and ultrasound devices. Phonons stand for quantum energy of lattice vibrations. Quantized phonons play a critical role in determining electronic transport and thermal properties of nanostructured devices. Phonon modes and the interaction of electron-phonon influent physical properties of the material. So, phonons have been an important field of research in condensed matter physics and electronics.In this thesis, the acoustic-phonon modes, the electronic subband energy structure, electron-acoustic-phonon interaction, and the spectrum of acoustic-phonon excitation in metallic NW embedded in Al2O3template were investigated. We study how the different nanowire radiuses and template material radiuses change acoustic-phonon modes with different quantum number m, v, the electron-phonon interaction and the spectrum of acoustic-phonon excitation in nanowire (NW) systems. Moreover, we also study how system temperatures effect electron-acoustic-phonon interaction and the spectrum of acoustic-phonon excitation. We present a detailed theoretical study which demonstrates that in cylindrical metallic nanowire (NW) structures realized from the state-of-the-art nanotechnology, such as Cu NW embedded in Al2O3template, the quantized acoustic-phonon modes can be achieved. The phonon modes are examined by solving the wave equations with corresponding boundary conditions. Based on phonon modes, we also studied the electron-phonon interaction and the spectrum of acoustic-phonon excitation in the metallic NW structures. This study is helpful for the application of metallic nanowire structures as hypersonic devices.The main theoretical results are as follows:Firstly, in small qz regime, the phonon mode does not exist in the metallic nanowire. With increasing phonon wave vector qz, allowed phonon modes appear and more phonon modes with different quantum states can be obtained.Then, the phonon frequency increases almost linearly with qz in metallic NW structures.In addition, the acoustic-phonon modes depends strongly on nanowire radiuses, but the template material radiuses does not affect the phonon modes.Finally, the electron-phonon interaction and the spectrum of acoustic-phonon excitation depend strongly on system temperatures, nanowire radiuses, electron states and phonon states. Acoustic-phonon excitation increase with system temperature increasing and nanowire radiuses decreasing.