CAREER: Integrated Approach for Modeling Thermal Energy Transport in Mesoscale Arrays of Nanostructures

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

CAREER: INTEGRATED APPROACH FOR MODELING THERMAL ENERGY TRANSPORT IN MESOSCALE ARRAYS OF NANOSTRUCTURES CAREER Award: 0547588 Jennifer R. Lukes Department of Mechanical Engineering and Applied Mechanics University of Pennsylvania Philadelphia, Pennsylvania 19104 ABSTRACT Physically meaningful yet computationally expedient multiscale thermal modeling methodologies are critical for the de novo design of advanced nanostructured materials for power generation and electronics thermal management. The nanoscale building blocks of these materials, including quantum dots, nanowires, and ultrathin solid films, are typically configured in arrays covering microns to centimeters and unexpected thermal transport phenomena arise from the interplay of different physical processes at the various length scales involved. The key question in developing modeling methodologies in such arrays is how to integrate disparate thermal models appropriate only at certain length scales into a coherent framework spanning several orders of magnitude. The research program proposed here will address this question by combining tight binding quantum mechanics, molecular dynamics, and Monte Carlo simulation to create a new modeling tool that links the length scales using two physically meaningful quantities: phonon scattering functions and phonon relaxation times. Comprehensive experimental studies for validation and improvement of the modeling tool will also be a significant part of this research effort. These studies will involve fabricating novel nanomaterial test samples in various configurations, characterizing their structures and chemical compositions, measuring their thermal conductivities, and comparing to modeling results for the same structures. Intellectual Merit This research program will make valuable contributions, both fundamental and applied. On the applied side, the modeling tool will be a critical step forward enabling the design of engineered thermal nanomaterials and the experimental studies will explore new techniques for wide-area (centimeter-scale) fabrication of arbitrarily patterned nanostructure arrays. On the fundamental side, the database of phonon scattering functions, relaxation times, transmission coefficients, and specularity parameters created in this study will provide vital new microscopic information to the nanoscale thermal transport community that has been largely inaccessible experimentally. This information will be key for the future resolution of current questions in the field such as the frequency dependence of Umklapp scattering processes, phonon behavior at material interfaces, and phonon interactions in the vicinity of nanostructures. Broader Impacts This CAREER proposal outlines a tightly integrated program of research and education. Graduate research activities form the core of the program, and results from the research will be conveyed directly to undergraduates from underrepresented groups through summer research projects, to the public through journal publications and free software, to the undergraduates through the introduction of micro and nano topics into the curriculum, and to the graduate students through synergistic teaching and research.