Piezotronic Tuning of Potential Barriers in ZnO Bicrystals

Coupling of magnetic, ferroelectric, or piezoelectric properties with charge transport at oxide interfaces provides the option to revolutionize classical electronics. Here, the modulation of electrostatic potential barriers at tailored ZnO bicrystal interfaces by stress-induced piezoelectric polarization is reported. Specimen design by epitaxial solid-state transformation allows for both optimal polarization vector alignment and tailoring of defect states at a semiconductor-semiconductor interface. Both quantities are probed by transmission electron microscopy. Consequently, uniaxial compressive stress affords a complete reduction of the potential barrier height at interfaces with head-to-head orientation of the piezoelectric polarization vectors and an increase in potential barrier height at interfaces with tail-to-tail orientation. The magnitude of this coupling between mechanical input and electrical transport opens pathways to the design of multifunctional electronic devices like strain triggered transistors, diodes, and stress sensors with feasible applications for human-computer interfacing.