Preparation, Performance And Secondary Growth Of One Dimensional Cu Doped ZnO Nano-materials

ZnO is a versatile compound semiconductor with great potential in areas such as optical-electronics, spintronics, and bio-sensors for its unique chemical and physical properties. In this work, we prepared vertically aligned ZnO and ZnO:Cu nanorod arrays through Chemical Vapor Transport method and did the secondary growth on ZnO and ZnO:Cu nanorod arrays. A detailed investigation on the growth mechanism, optical and magnetic properties of Cu doped ZnO and secondary growth ZnO nanowire arrays has been made. A qualitative discussion has been made on the origin of the room-temperature ferromagnetism in Cu doped ZnO.The primary results are described as following:1. We have investigated the different growth behavior on substrates with different treatments. Good controlment has been achieved for ZnO nanowire arrays. Temperature-dependent photoluminescence spectra indicate the exsit of strong surface exciton (SX), free acceptor (FA) related emission. No room temperature ferromagnetism (RTFM) is observed in ZnO buffer and ZnO nanowire arrays.2. ZnO:Cu nanowire arrays is synthetized by adding CuO as the doping source. Strong green emission is observed in ZnO:Cu samples with great restraint of the band gap emission. Strong RTFM is observed in Cu doped ZnO nanowires with strong relation to vaccum annealing induced defects.3. Based on the ZnO:Cu nanorods array, an island nucleation is observed during the secondary growth process. The modified characteristic radius (Rc) model is used to explain the nucleation and secondary growth process. Temperature-dependent photoluminescence spectra indicate that the band gap emission of the secondary growth nanorods is greatly restrained. A controversial 3.31 eV emission (A line) and two different donor-acceptor pair (DAP) recombination at 3.24eV and 2.48eV are observed at 13K. Intrinsic room temperature ferromagnetism (RTFM) is observed in the secondary growth ZnO:Cu nanorods and it can be explained by oxygen vacancy and copper defects related bound magnetic polar (BMP) or double exchange mechanism based on copper ions with different valences. Based on the ZnO:Cu nanorods, we also start some work on the fabrication of ZnO:Cu nanowire FETs.