THERMAL TRANSPORT IN TWO-DIMENSIONAL SEMICONDUCTOR MATERIALS

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Semiconductor thin films are building blocks for all modern electronics devices. In recent years, new semiconductor thin films consisting of crystalline single layer of atoms or stacks of a few crystalline atomic layers have been found to possess extraordinary properties. These new materials promise new devices in information technology, energy, and health care, and possibly in quantum technology. Understanding thermal transport in these new materials is important as heat dissipation has a large influence on the device performance. Thermal transport is also closely related to energy conversion processes such as thermoelectrics and photovoltaics. This project will investigate the fundamental and important issues of thermal transport in semiconductor materials to enable thermal design and thermal management in these materials and devices.The proposed project is built upon investigator’s extensive expertise in thermal transport processes, especially in the development of experimental methods for thermal transport research. The proposed project will employ advanced experimental tools to investigate the following fundamental problems: (1) the individual contributions of electrons and phonons to thermal transport in semiconductor thin films, (2) the relation between electrical and thermal transport by electrons in semiconductors, and (3) the bipolar diffusion which contributes to thermal transport in semiconductors, especially in low-bandgap two-dimensional semiconductor materials. Collectively, these studies will allow for measuring electric thermal conductivity, phonon conductivity, and total thermal conductivity, determining the value of the Lorenz number, evaluating the effect of bipolar diffusion, and investigating ultrafast energy scattering processes that are fundamental to the energy transport processes. The experimental work will be supplemented by computational studies to provide insights to the experimental results. The research outcome will contribute to many on-going studies in thermal transport in micro and nanoscale materials and devices, lead to much improved fundamental understandings of thermal transport by different energy carriers in semiconductors, and provide possible means to control thermal transport in semiconductor devices.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.