Static Finite Element Modeling for Sensor Design and Processing of an Individually Contacted Laterally Bent Piezoelectric Nanowire

We report on the static finite element simulations of the representative elementary pixel of an arrayed force-sensing device. Our goal is to provide quantified guidelines for adjusting pixel geometry and tuning technological parameters in a view to on-chip device fabrication, according to the targeted device performance or usage. The force sensitive pixel consists of an individual piezoelectric nanowire (NW), selectively grown on a material stack representative of the targeted process, and with side electrodes. The model takes into account the full pixel environment but makes the assumption of purely insulating materials (no free charges). We found that the piezopotential collection factor was strongly dependent on the stack characteristics. A 69% collection factor was obtained when a 5-nm-thick growth-seeding ZnO layer was introduced directly below the NW. We also simulated micro-fabrication related defects, such as the loss of physical contact between the NW and the electrodes, and found that the collection factor dropped to 33% for a 3 nm gap before stabilizing. Our results provide important guidelines for the optimization of the overall sensor response and calibration, with resulting constraints on NW growth conditions and substrate patterning, as well as collected data dispersion sources for posttreatment purposes.