Development of Thermoelectric Thick-films via Electrophoretic Deposition

Abstract

Technological advancements in the past few decades have led to major improvements in living conditions; but, these improvements have come at a steep environmental price. Unsustainability, air pollution, greenhouse emissions, global warming, fragility of fossil-derived energy economies and sadly the yearly death rate of hundreds of thousands of people are the most important reasons that have forced the scientists and governments to think about novel renewable energies in order to solve the epic challenge of 21st century.Among different forms of clean renewable energies, this thesis is dedicated to study thermoelectric power generation. Thermoelectric materials enable electrical power generation from the waste heat through a direct conversion, silent operation and low environmental load. These materials that operate at a wide range of temperatures and are easily scalable have relatively low efficiencies. Despite many progresses that have been made in bulk thermoelectric materials, there is still a lot of works to be done in fabrication of thermoelectric thin/thick-films.This thesis studies fabrication and characterization of silicon germanium thermoelectric thick-films grown via electrophoretic deposition. Initial boron-doped SiGe/Glass powder was prepared though milling and in the electrophoretic deposition, Si wafer and sapphire discs have been used as the substrate. X-ray diffraction, scanning electron microscopy and laser scanning electron microscopy have been used for phase identification, morphology studies and surface topography, respectively. Seebeck coefficient and electrical conductivity were measured by the commercially available equipment; while the thermal conductivity of the films was measured by a laser flash unit. At last, TE figure-of-merit (ZT) was calculated.