Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 151010

151010 - Strong Temperature Dependence of Interfacial Thermal Resistance Between Single-Walled Carbon Nanotube Bundle and Silicon Dioxide 

As micro/nanoelectronics continue to shrink in size and expand in capability, dissipating heat becomes a critical factor for their operational efficiency. This has led to significant interest in studying interfacial thermal resistance (ITR) since it dictates the overall thermal transport at nanoscale dimensions. Despite its importance, ITR evolution with temperature is not well understood yet due to the challenges in nanoscale characterization and the lack of a universal model to describe its temperature dependence. Existing models that are based on phonon scattering at the interface only work well under limited set of conditions. Here, we report a comprehensive investigation of the temperature dependent ITR for Single-Walled Carbon Nanotube (SWCNT) bundle with lateral dimension of less than 8 nm on a silicon dioxide substrate.  The nanosecond-resolved Raman thermal probing offers a significant advantage over traditional techniques for being very sensitive and its non-destructive nature. In this work, we utilize the energy transport state-resolved Raman (ET-Raman) technique which ensures accurate measurements by eliminating uncertainties associated with laser absorption and Raman temperature coefficients, which are required in conventional Raman measurements. The sample's structure was analyzed using an atomic force microscope, and the Raman scan focused on radial breathing modes, which are size-dependent. The changes in the Raman spectrum, particularly the G band, were analyzed under continuous wave (CW) and 20 ns pulsed laser heating to deduce the thermal response of the SWCNT under steady-state and transient heat conduction. We map the observed experimental results onto the solution of the heat conduction model to infer the ITR. The sample is probed over the temperature range 77-297 K and the ITR is observed to decrease from (1.56-1.74)×10⁴ to 530-725 K∙m∙W^-1, respectively. The reported results at room temperature are quantitatively in line with previously reported data for SWCNT/SiO₂ interface. The temperature-dependent ITR was compared with predictions from the phonon diffuse mismatch model (DMM), showing good qualitative agreement. However, the DMM predicted lower ITR values, consistent with the model's tendency to overestimate phonon group velocity near the Brillouin zone boundary due to the Debye approximation of linear dispersion. We observe that the temperature dependency of the ITR takes the form of T^-n where n is found to be 2.4 and 2.56 for two different locations of the sample. This dependency (when inverted to represent the interfacial thermal conductance) mirrors that of phonon heat capacity at temperatures well below their Debye temperature. To isolate the intrinsic effect of temperature on interfacial energy coupling, we introduced the concept of effective interface energy transmission velocity (v_i,eff), defined as the ratio of interfacial thermal conductance to volumetric heat capacity. Interestingly, we find that v_i,eff shows little variation over a wide temperature range for various reported interfaces. A plausible interpretation for such constant value is that the heat transport at the interface is dominated by elastic phonon transmission and there is little to no inelastic contribution, except when v_i,eff vary significantly. Further exploration and refinement of this concept and its relevance to the temperature-dependent ITR is expected in future research work.

Presenting Author: Ibrahim Al Keyyam Iowa State University

Presenting Author Biography: A second year PhD student majoring in Mechanical Engineering with dual minors in Physics and Materials Science at Iowa State University.

Authors:

Ibrahim Al Keyyam Iowa State University
Xinwei Wang Iowa State University