Study On The Field Emission Materials Zinc Oxide Nanorods, Diamand-like Carbon:Preparation And Its Structure And Performance

Zinc oxide (ZnO) with a wide band gap (Eg=3.37eV) and large excition binding energy (Eb=60meV) has been an interesting research topic since it has great potential for various applications, such as FED, light emitting diodes (LED), transparent conducting oxide, sensors for chemicals and gases, surface acoustic wave devices, ultraviolet emitters etc. The nanorods of oxide semiconductor are known to have an advantage for field electron emitters to work at low vacuum without significant degradation of their characteristics. In this thesis, firstly introduce the structure and basic properties of the ZnO materials, and its application prospect in field emission displays. And then focus on the enhanced field emission effect of one-dimensional ZnO nanorods and nitrogen, aluminum doped features. Finally, studied the field emission materials of diamond-like carbon film (DLC). Contents are divided into the following sections:1. Self-assembled ZnO nanorods/graphene field emission structures were fabricated by using a hydrothermal growth of nanorods on few layer graphene (FLG) substrates. The FLG patterned electrode was used to improve the contact resistance and to control the density and the area of field emission. This approach allows creation of high-performance field emission devices over a large area using an inexpensive low-temperature growth and FLG patterned substrates. The obtained ZnO NRs/FLG field emission structures operate at a low vacuum of10"5Torr and low turn-on electric field of0.9V/μm, demonstrating a high field enhancement factor p=5556.2. Nitrogen-doped ZnO nanorods were synthesized through thermal diffusion of nitrogen in an aqueous solution at90℃. Low-temperature photoluminescence measured at10K showed two peaks located at3.353and3.242eV, which were assigned to the acceptor-bound excitons and donor-acceptor pairs, respectively. The conductance of the nitrogen-doped ZnO nanorods increased1.5times compared with Al-doped samples and5.8times compared with undoped ZnO nanorods. 3. We present a simple way to prepare low-resistance ZnO nanorods by hydro thermal self-assembled growth at95℃and in situ doped with Al. The NRs were grown on graphene/Ni/Si and annealed at400℃. Few layer graphene was used to assist aligned growth of the NRs and acted as an electrode during electric measurement. The measurement showed resistance of the Al-doped ZnO NRs100times lower than that of undoped ZnO NRs. Photoluminescence measurement showed enhanced deep level emission for the Al-doped NRs and low temperature photoluminescence study showed coexistence of acceptor bound-exciton (3.353eV) and donor bound-exciton (3.362eV).4. Ion source assisted cathodic arc ion-plating was used to synthesize molybdenum containing diamond-like carbon films (Mo-DLC).The element of molybdenum is uniformly distributed in our sample as analyzed by RBS. The Mo content in the films was controlled by varying of the acetylene gas flow rates. The root-mean square (RMS) roughness of the as-deposited sample was found in the range of1.5nra. The hardness of35GPa has been achieved at the optimum conditions of synthesis. This can be attributed to the self-formation multilayer structure during deposition process and the formation of hard molybdenum carbide phase with C=Mo bonding. The results show that ion source assisted cathodic arc ion-plating is an effective technique to fabricate metal-containing carbon films with controlled metal contents.