Title: Interfacial phonon scattering and transmission loss in $>1$ µm thick silicon-on-insulator thin films

Abstract

Scattering of phonons at boundaries of a crystal (grains, surfaces, or solid/solid interfaces) is characterized by the phonon wavelength, the angle of incidence, and the interface roughness, as historically evaluated using a specularity parameter p formulated by Ziman [Electrons and Phonons (Clarendon Press, Oxford, 1960)]. This parameter was initially defined to determine the probability of a phonon specularly reflecting or diffusely scattering from the rough surface of a material. The validity of Ziman's theory as extended to solid/solid interfaces has not been previously validated. Here, to better understand the interfacial scattering of phonons and to test the validity of Ziman's theory, we precisely measured the in-plane thermal conductivity of a series of Si films in silicon-on-insulator (SOI) wafers by time-domain thermoreflectance (TDTR) for a Si film thickness range of 1–10 μm and a temperature range of 100–300 K. The Si/SiO₂ interface roughness was determined to be 0.11±0.04nm using transmission electron microscopy (TEM). Furthermore, we compared our in-plane thermal conductivity measurements to theoretical calculations that combine first-principles phonon transport with Ziman's theory. Calculations using Ziman's specularity parameter significantly overestimate values from the TDTR measurements. We attribute this discrepancy to phonon transmission through the solid/solid interface into the substrate, which is notmore » accounted for by Ziman's theory for surfaces. The phonons that are specularly transmitted into an amorphous layer will be sufficiently randomized by the time they come back to the crystalline Si layer, the effect of which is practically equivalent to a diffuse reflection at the interface. Finally, we derive a simple expression for the specularity parameter at solid/amorphous interfaces and achieve good agreement between calculations and measurement values.« less

Authors:

Jiang, Puqing ^[1]; Lindsay, Lucas R.  ^[2];

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Huang, Xi ^[1]; Koh, Yee Kan ^[1]

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1. National University of Singapore (Singapore). Department of Mechanical Engineering
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division

Publication Date:

Thu May 17 00:00:00 EDT 2018

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1439937

Alternate Identifier(s):

OSTI ID: 1437515

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review B

Additional Journal Information:

Journal Volume: 97; Journal Issue: 19; Journal ID: ISSN 2469-9950

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY