ABSTRACT
ZnO has a long history as a material for gas sensing, varistors, piezoelectric transducers, as a lighttransmitting electrode in optoelectronic devices, electro-optic modulators, and as a sunscreen.1 In the last few years, major advances have been made in the areas of conductivity control and availability of high-quality bulk ZnO substrates. This work has refocused attention on ZnO for UV light emitters and transparent electronics. ZnO can be grown at relatively low temperatures on cheap substrates such as glass and has a larger exciton binding energy (~60 meV) than GaN (~25 meV).2-22 In addition, the advances in growth of ZnO nanorods and nanowires have suggested that these may have applications to biodetection,22 because of their large surface areas. Finally, incorporation of percent levels of transition metal impurities such as Mn leads to ferromagnetism in ZnO with practical Curie temperatures. This suggests that ZnO may be an ideal host as a spintronic material.
