ZnO nanowires for LED and field-emission displays

The use of ZnO nanostructures in various display applications is reported. Single-crystalline vertically oriented nanowires with typical diameters of 100 nm and a length of 1-2 mu m were grown at deposition temperatures below 100 degrees C. Homogeneous growth over areas up to 50 cm(2) on Si as well as on various metallic, transparent, and flexible substrates were obtained. Visible electroluminescence in the region between 400 and 900 nm and narrow-line near-ultraviolet (UV) electroluminescence is demonstrated. The physical conditions leading to single-crystalline growth at low temperature, the role of defects, and the possibility of doping are discussed. These issues present the main challenges on the road towards high emission rates in LED operation. Under certain conditions, sharply tipped wires can be grown that hold promise for field-emission applications.