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oai:www.ideals.illinois.edu:2142/90672 2023-07-11 col_2142_5131 com_2142_5130

Aluru, Narayana R. De, Subhadeep 2016-07-07T19:58:14Z 2016-07-07T19:58:14Z 2016-04-28 2016-05 The goal of this research is to study the role of surface on intrinsic dissipation in silicon (Si) nanostructures. We look at two different cases namely (i) Si(100) surface with (2x1) reconstruction and (ii) Hydrogen (H) terminated Si surface. We utilize molecular dynamics (MD) simulations and show that the two surfaces play opposing role on intrinsic dissipation. While surface defects always aid in the entropy generation process, the scattering of phonons from rough surfaces can suppress Akhiezer damping. For the case of (2x1) reconstructed silicon surface, the former dominates and the inverse quality factor (Q^-1) is found to increase with the decrease in size. However, different scaling trends are observed in the case of a H-terminated silicon surface with no defects and dimers. Particularly, in the case of a H-terminated silicon, if the resonator is operated with a frequency Ω such that Ωτph < 1, where τph is the phonon relaxation time, Q^-1 is found to decrease with the decrease in size. The opposite scaling is observed for Ωτph. A simplified model, based on two phonon groups (with positive and negative Grüneisen parameters), is considered to explain the observed trend. We show that the equilibration time between the two mode groups decreases with the decrease in size for the H-terminated structure. We also study the scaling of Q factor with frequency for these cases. Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2016-07-07 without embargo terms The student, Subhadeep De, accepted the attached license on 2016-04-26 at 16:07. The student, Subhadeep De, submitted this Thesis for approval on 2016-04-26 at 16:22. This Thesis was approved for publication on 2016-04-28 at 13:33. DSpace SAF Submission Ingestion Package generated from Vireo submission #9530 on 2016-07-07 at 13:33:36 Made available in DSpace on 2016-07-07T19:58:14Z (GMT). No. of bitstreams: 2 DE-THESIS-2016.pdf: 3969296 bytes, checksum: 93d474caf39069528138fe9414b86d1d (MD5) LICENSE.txt: 4209 bytes, checksum: 2f3313fef19a0dabdaa7095d049ddf07 (MD5) Previous issue date: 2016-04-28 application/pdf http://hdl.handle.net/2142/90672 en Copyright 2016 Subhadeep De intrinsic dissipation, Akhiezer, MD, surface, phonon Theory and simulation of surface effects on intrinsic dissipation text text Mechanical Sci & Engineering Mechanical Engineering University of Illinois at Urbana-Champaign Thesis M.S.