Summary:
The aim of the thesis is the development and characterization of tribogenerators based on high-k dielectric materials in order to harvest abundant mechanical energy. Harvesting energy from small-scale mechanical movements and converting it into electricity to supply autonomous electronic systems is a research field that is being studied globally. The principle operation of the tribogenerators studied in this work, is based on the exploitation of the triboelectric phenomenon that occurs during the friction between two different surfaces.
Silicon wafers were used as the substrates to fabricate the tribo-pairs used in this work. The high-k dielectric materials were developed by the Atomic Layer Deposition technique (ALD) in different thicknesses. The dielectric materials used were aluminum oxide Al2O3, hafnium oxide HfO2, tantalum oxide Ta2O5 and zirconium oxide ZrO2. The roughness analysis of the formed surfaces was performed using the Atomic Force Microscopy (AFM) in order to investigate the specific topography of each sample.
Furthermore, the electrical characterization of each deposited material was done in two different fundamental operation modes, the contact-Separation mode and the Lateral Sliding mode. Also, the energy storage capacity of the tribogenerators was studied in an external capacitor using a quadruple circuit. The results of the measurements indicate different behavior for each of the oxides used. From the analysis of the experimental results it appears that the triboelectric effect is influenced by various factors such as the type of dielectric the thickness of the deposited film, the roughness of the surfaces of the tibo-pairs. The complexity of the triboelectric phenomenon, which has not yet allowed a complete explanation of its operating mechanism, requires a careful design of the tribogenerators and, in particular, the control of the surface roughness which seems to have the greatest effect on tribogenerator output performance.
Keywords:
Energy Harvesting, Tribogenerator, triboelectric effect, high dielectric constant Atomic Force Microscopy AFM
