The metal/oxide hetero-structure has attracted much attention in recent decades because of its potential in various applications such as heterogeneous catalysis. In particular, the combination of magnetic metal with an oxide thin film, e.g., the magneto-tunneling junction, has been widely studied and applied in data storage and spintronics. ZnO is one of the important semiconducting materials, not only for photoluminescence but also more importantly for its promising applications in spintronics. Transition metal-doped ZnO is predicted to be useful as a magnetic semiconductor for room-temperature (RT) application. Furthermore, ZnO exhibits the largest electromechanical response, among the known tetrahedral semiconductors, which makes it suitable for devices in microelectromechanical and communication systems.