ZnO nanostructures: Current status and future prospects

ZnO is unambiguously a tantalizing choice of material for applications in electronics, photonics, acoustics, and sensing due to its remarkable piezoelectric and semiconducting properties. Its rich family of nanostructures and large excitation binding energy (60 meV) gives it a further edge over other semiconductors such as GaN. However, lack of control over shape, size and reliable p-type doping of ZnO crystals presents great challenges for today's technology and hinders its practical applications. Here we present a comprehensive review of synthesis of ZnO nanostructures by vapour phase transport and solution phase methods with a special emphasis on p-type doping and its application in state-of-the-art devices for future applications.