Selective Chemical Vapour Deposition for Production of Thermoelectric Micro-Generators for Energy Harvesting

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Thermoelectric micro-generators are solid state devices that can provide constant sources of electricity. They have a number of very favourable features, i.e. no mechanical parts that can wear out, require little maintenance, have long lifetimes and produce no emissions. Solid-state thermoelectric devices are based upon one of two phenomena, the Seebeck effect, which can be used for power generation (energy harvesting), and the Peltier effect for electronic cooling or heating. In order to produce a functional thermoelectric device, an n-type doped material is connected electrically in series and thermally in parallel across a temperature differential to a p-type doped material, so that current flows between the two. Bismuth telluride based thermoelectric materials are very well suited for near room temperature applications, including wireless sensing. Through recent research supported by STFC, we have developed a new series of molecular precursor compounds which can be used in chemical vapour deposition to produce high quality thin films of (n-type) bismuth telluride and (p-type) antimony telluride. Unusually, our precursors and CVD-based system allows the materials to be deposited very selectively onto specific areas of lithographically patterned substrates. The focus of this project is to work closely with key stakeholders, including a thermoelectric device company and a specialist precursor manufacturer, to exploit the unique features of our precursors and CVD-based approach so that the production costs for manufacture of thermoelectric micro-generators can be reduced significantly. Since the actual production costs account for the majority of the unit cost per thermoelectric generator, reducing this is a high priority to allow penetration of these micro-generator devices into new and larger markets. Validation and benchmarking of the key thermoelectric properties of our CVD-produced thermoelectric micro-generators is central to the work, and this will also provide the key data necessary to evaluate the prospect of using our CVD-based approach for TE micro-coolers for future applications such as on-chip cooling of microprocessors.