Sustainable wafer-scale integration of epitaxial ZnO on silicon for piezoelectric devices

To sustainably support the ongoing energetic transition, we need functional metal oxides capable of converting energy, and produce storage, and sensing devices. However, these materials suffer from a high economic cost of manufacturing, and their production in a sustainable way is, to date, a milestone. Additionally, the technical challenges, such as scalability and integration of silicon for industrial processing using microelectronic technologies, impose strict conditions for the entire materials process. In this work, we engineer α-quartz virtual substrates up to 4 inches facilitating the large-scale and sustainable integration of multifunctional epitaxial ZnO metal oxide microwire films on silicon. These materials are exclusively manufactured on silicon using solution chemistry, providing single-chip solutions that can meet strict economic constraints for developing sustainable devices at a lower cost. Through this integrative technology, we demonstrate the microfabrication of epitaxial (110)ZnO/(100)α-quartz/(100)silicon piezoelectric membrane resonators at the wafer-scale with potential applications in energy conversion and sensing. We combined four dimensional (4D)-STEM diffraction technology and Piezoelectric Force Microscopy (PFM) to establish a correlation between out of plane crystalline strain and piezoelectric response in epitaxial (110) ZnO at the microscale. Finally, we proved the fabrication of 800 nm thick (110) ZnO suspended membranes that can be transferred to flexible substrates, making them suitable for flexible devices.