Rapport d'activité final du Projet 'Unconventional Principles of Thermoelectric Generation' ; Rapport d'activité final du Projet 'Unconventional Principles of Thermoelectric Generation': ERC StG 338179

Thermoelectric energy harvesting offers strong advantages to supply low power electronics such as sensing, wireless, mobile and communicating devices that are increasingly changing our environment. Thermal energy sources are indeed abundant and widespread in our homes, factories and even our own body can be seen as a heat source. This matches very well the power needs of Ambient Intelligence, Internet of Things and Body Area Networks. Unfortunately, state-of-the-art thermoelectric converters still rely on rare and potentially harmful elements and feature low compatibility with low-cost mainstream production lines. The "Unconventional Principles of ThermoElectric Generation" project (UPTEG), explored two radically new approaches to overcome these limitations. First, the project aimed at making an artificial thermoelectric material out of silicon, one of the most abundant element on earth which is also at the heart of today's information technologies. To that end, a new process was developed to fabricate fully suspended silicon thin films patterned at the nanoscale following the concept of Phononic Engineering Converters. This concept uses a pattern of holes at the right length scale to hinder the heat flow while preserving electrical current conduction, resulting in augmented thermoelectric performance of the material. This approach lead to several remarkable results. First, we simulated, estimated and designed thin-film planar converters architectures. We then developed a versatile process that enables the fabrication of a variety of devices fully compatible with silicon MEMS technologies. In addition, we quantified heat transport at nanoscale using three complementary methods, namely: Electro-thermal, Raman thermometry and Scanning Thermal Microscopy. Not only the results show the consistency of these methodologies for the first time, they also demonstrate that heat conduction has been divided by a factor 15. From the fundamental point of view, these artificial materials could solve the well-known "phonon ...