Two Dimensional Thermoelectric Transport and Transient Energy Conversion

Thermal management is crucial to modern electronic technology as ICs are becoming denser each decade. With higher density comes the challenge of managing the increased energy dissipation densities and large local temperatures. The stable and reliable operation of modern advanced electronics requires good thermal management. The primary objective of this dissertation is to study thermal and thermoelectric transport in two-dimensional thin-film systems of materials for good thermal management applications. A high-efficiency thermoelectric device can draw heat to convert it into electrical energy efficiently, and hence it can be used to cool on-chip devices. Such thermoelectric devices can also be used to convert waste heat into electrical power. Traditional bulk thermoelectric modules cannot be effectively integrated into on-chip applications. Two-dimensional geometries, including thin films and few-layer 2D materials, offer better compatibility, scalability, and potential for integration. This research aims to investigate in-plane thermal transport in two-dimensional systems, including silicon-based nanostructured thin films and layered materials (NbSe2, 2H-MoTe2, and PtSe2), addressing limitations in traditional measurement techniques. By studying their temperature dependence, this work aims to expand the scarce literature on in-plane thermal conductivity, particularly in transition-metal dichalcogenides (TMDs) and group III monochalcogenides. Measuring nanometer-thick samples provides fundamental insights into phonon transport, advancing their potential for thermal management applications. Beyond thermal properties, I explore thermoelectric performance in BiSb thin films on nanostructured substrates and two-dimensional γ-InSe, examining key factors influencing efficiency in device applications. Finally, this research concludes with a novel solid-state energy conversion device operating on a thermodynamic cycle inspired by the Otto cycle. Unlike conventional thermoelectric or thermionic generators, it harnesses electron gas dynamics for energy conversion, operating beyond Carnot’s efficiency and unlocking new possibilities for thermal-to-electrical energy conversion.