| One-dimensional semiconductor nanomaterials are now being studied for their novel physical properties. Among them, nanowires and nanotubes are at the frontier of materials science owing to their unique chemical, physical and mechanical properties, with the most interesting applications in nanoelectronics. At present, various one-dimensional nano-materials, for instance, carbon nanotubes, have been synthesized and their field emission properties were studied, but the commercial realization in field emission display are still full of challenges, because of the complicated synthesis technique and difficulty in purifying the mixture of the metallic and semiconductor carbon nanotubes.Metal-organic complexes of M-TCNQ have columnar stacking structure, which can be used to synthesize the nanowires. So the interest to study their electrical property, and further realize the novel nano-electronic devices was initiated. In this dissertation, the synthesis and field electron emission properties of M(Ag,Cu)-TCNQ nanowires were studied.Firstly, growth conditions of Ag,Cu-TCNQ micro/nanostructures by the vapor transport reaction were systematically investigated. It is exciting that the semiconducting nanowires of Cu-TCNQ phase I was obtained by this method which is hard to synthesize by the solution reaction method. It was also found that the thickness of M(Ag, Cu) film, reaction temperature and time greatly influence the diameter, density and alignment of the resulting nanowires. The formation processes of Ag-TCNQ nanowires proceed through the steps of nucleation and directional growth, which are governed by the vapor-solid growth mechanism. Other morphologies such as belts and flowers were also obtained due to some uncontrollable variations in the growth conditions.The I-Vcurve for a two-terminal device with a single Ag-TCNQ nanowire shows that it has the electric bistable property, similar to the Ag-TCNQ films. A prototype of over-voltage protector made of the nanowires array has good performance with the response time shorter than 870 ns.The field-induced electron emission from the Ag, Cu-TCNQ nanowires were measured, respectively. Results show that M-TCNQ nanowires grown with the 10-20 nm metal film have a low turn-on field of about 2.0 V/μm, and the nanowires on metal substrate has current density of about 0.5 mA/cm~2 at 2.0 V/μm for Ag-TCNQ, 0.6mA/cm以~2 at 0.7 V/μm for Cu-TCNQ, respectively, higher than those nanowires on Si substrate. The process of electron emission is similar to the two-process model. The stability in emission current can be improved by depositing a LiF layer on the surface of the M-TCNQ nanowires. Therefore, M-TCNQ nanowires are believed to be a candidate for displaying information.In summary, the synthesis of one-dimensional M-TCNQ nanowires and their potential application in field emission were investigated. These studies may be useful for the crystal growth, organic nano-devices such as electric switches and information storage, and potential application in cold cathode materials for information display.
|
PDF Full Text Request