Dissertation > Excellent graduate degree dissertation topics show

Phonon Scattering in Doped Silicon by Molecular Dynamics Simulation

Author: ZhouMin
Tutor: YaoMan
School: Dalian University of Technology
Course: Materials Processing Engineering
Keywords: doped Silicon phonon scattering molecular dynamics resonance
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 119
Quote: 0
Read: Download Dissertation

Abstract


When device is small enough to a certain scale,the experimental measurement is not able to reflect the microcosmic mechanism of heat transfer,so numerical simulation technology becomes an important means to study these mechanisms with the rapid development of modern computer simulation technology.Phonons play a great role in the microcosmic mechanism of heat transfer of silicon,the process of phonon scattering in doped silicon is studied by molecular dynamics simulation with high performance computers in this paper, then the composition of energy is analyzed after scattering,in which the greater transmitted energy means the high thermal conductivity qualitatively.In addition,some parameters on the effects of thermal conductivity are taken into consideration,especially the atomic mass of dopants,These results could be significant for deep understanding of the effect of microcosmic mechanism of point defect on lattice heat transfer.The steps of simulation process are as follows:firstly generating the phonon wave packet with well-defined frequency,building molecular dynamics model and determining related parameters,and then performing the simulation,finally analyzing the transmitted and reflected energy quantitatively.The evolution of phonon scattering from point defects has been explicitly displayed in the atomic scale,which can not be currently observed by actual experiments,it is visually shown the transmitted energy,reflected energy,and captured energy gradually release in the doped area.The results show that:the isotope dopants can lead to a dramatic drop of transmission coefficient in the specific phonon frequency region,cutting down the transmission coefficients greatly,which attributes to the local resonance caused by dopants.Transmission coefficients decrease obviously with greater incident phonon frequency. When the doped concentrations increase,initial resonant frequency becomes lower while the resonant region becomes larger,but the value of frequency where the minimum transmission occurs is not affected.In the same frequency and concentration,the greater the atomic mass of dopants,the more obvious drop of transmission coefficient,the greater drop in thermal conductivity at the same time.The studies on lognitudinal acoustic(LA) and transverse acoustic(TA) modes phonons indicate that,when the atomic mass of dopants are lighter,energy of LA phonon mode is always greater than that of TA phonon mode.It will be more complicated with heavier dopants,the total transmitted energies are mainly constituted by LA phonons in the lower frequency region than the resonant frequency,however,in the resonance region and higher frequency region,the energy presenting by TA phonons can not be neglected,there is obvious conversion from LA to TA phonon mode,and the proportion of TA mode increases as the atomic mass increases,the situation that the energy of TA mode is more than of LA mode even appears.According to pure silicon phonon dispersion,the group velocity of LA is greater than that of TA,so with the same transmitted energy more LA mode is better for thermal conductivity of the material.These factors should be fully taken into account when analyzing the microcosmic mechanism of lattice heat transfer.

Related Dissertations

  1. Study on LC Resonance Charge and POS Based Pulsed Power Supply,TN782
  2. Study on the Fluorescence Analysis of Penicillins Antibiotics,R155.5
  3. MRI Guoded Experimental Cryoablation of Rabbit’s Sciatic Nerve for MRI and Pathology Contrast Study,R445.2
  4. Influence of Nanostructure on Hydrophobic Properties at TiO2 Surface Studied by Molecular Dynamics Simulation,O614.411
  5. Hydrophilic structure of different types of surface -modified polyurethane material and coagulation 12 factor nine peptide fragments,and fibrinogen P1 fragment of computer simulation of the interaction,O631.3
  6. The Clinic Value of Diffusion Weighted Whole Body Imaging with Background Body Signal Suppression (DWIBS) Compared with hPET/CT,R445.2
  7. Diffusion Tensor Imaging Study of Idiopathic Epilepsy at 3.0T High Field Magnetic Resonance Scaner,R445.2
  8. Studies on the Interaction between Biomolecules by Surface Plasmon Resonance Technology and Fluorescence Spectrometry,Q503
  9. The Application Value of Magnetic Resonance Diffusion Tensor Imaging in Skeletal Muscle Tumor,R445.2
  10. A Study of Wallerian Degeneration in Cortico Spinal Tract after Cerebral Infarction by fMRI,R445.2
  11. A Volumetric Study of External Capsule, Extreme Capsule and Inferior Frontal Gyrus White Matter in First-Episode Paranoid Schizophrenia,R749.3
  12. Healthy Chinese central olfactory structures related to MRI volume and olfactory function with age correlation,R445.2
  13. Multislice CT and MRI angiography in the diagnosis of Takayasu arteritis,R445.2
  14. 3.0T BOLD MR techniques on acute unilateral ureteral obstruction of renal damage,R693.2
  15. Progressive supranuclear palsy clinical and magnetic resonance imaging characteristics of,R741
  16. 3.0T high-field magnetic resonance imaging of the central type lung cancer preliminary study,R734.2
  17. MR diffusion weighted imaging in Application Value of osteonecrosis,R681.8
  18. Substrate microstrip bandpass filter parameters on the transmission characteristics of impact studies,TN713.5
  19. Fractional Differential resonance boundary value problems,O175.8
  20. Categories of Second Order Ordinary Differential Equations Existence,O175.8
  21. Magnetic field spin chain entanglement dynamics of particles in both,O413.1

CLC: > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials
© 2012 www.DissertationTopic.Net  Mobile