Influence of bottom electrode and seed layer on the growth of ZnO nanowires for vibrational energy harvesting
Résumé
Piezoelectric nanogenerators (PENG) have already shown their large potential in various
applications and more specifically to harvest energy and power up miniaturized device in the range of µW.cm-2. A successful nanowires (NWs) synthesis for PENG relies on the quality of the seed layer as clearly emphasized from previous work on ZnO single crystal substrate. In the following work we highlight efforts to improve fabrication process especially regarding the seed layers just prior to chemical bath deposition of ZnO NWs. Our fabrication strategy relies on scalable process and low temperature hydrothermal synthesis of ZnO NWs to maintain a relatively low device manufacturing cost. We emphasise here the possible use of Ti as bottom electrode together with a doped Silicon substrate. Despite a low electrical conductivity, Ti layer can be grown crystalline as hexagonal metallic layer while allowing rapid thermal annealing of the device after deposition of ZnO by PVD to obtain a seed layer with wurtzite fiber texture and large grains favourable to NWs growth and device performance.