Electromechanical properties of MgZnO/ZnO heterostructures on flexible polyimide and stainless steel substrates under flexing

We investigate the electromechanical properties of radio frequency (rf)-sputtered MgZnO/ZnO heterostructures on flexible polyimide (PI) and stainless steel 304 (StSt304) substrates. By subjecting ZnO to ultra-short (30–40 s) atmospheric pressure plasma jet treatment and prolonged (>3 h) thermal annealing at 300 °C, highly conductive interfaces are induced in rf-sputtered MgZnO/ZnO heterostructures on flexible PI and StSt304 substrates. The electrical properties of on-StSt MgZnO/ZnO annealed at 400 °C for 30 min are evaluated under the inward and outward bending conditions. Furthermore, the electrical properties of on-PI MgZnO/ZnO heterostructures annealed at 300 °C for 3 h are examined under the bending and stretching conditions. Compared with ZnO, MgZnO/ZnO heterostructures show better electrical stability under mechanical flexing; deviations in the electrical properties of MgZnO/ZnO heterostructures occur under larger strain levels. Piezoelectric polarization is induced under flexing, resulting in an increase or decrease in the resistance of MgZnO/ZnO heterostructures. (paper)