Abstract: A piezoelectric mechanical energy harvesting device is disclosed. The device is driven by environmentally-available mechanical energy. The device is an out-of-plane cantilever-based piezoelectric energy harvester based on ZnO nanostructures monolithically integrated with Schottky diodes and an entire-chip capacitor. ZnO will be utilized in two different forms: nanowires (NWs) and nanosheets (NSs). These nanostructures will be grown by a silicon-friendly hydrothermal process and using part of the top capacitor electrode as seed layer. A step-by-step process flow is proposed to integrate monolithically in a same device. This integration will allow reduced power losses and ease the combination of several generators without concerns about the stress and charge signs.