The Preparation Of Several Kinds Of Transition Metal Oxides Nanoarray Structures And Their Field Emission Properties

The key point of the successful applications of vacuum microelectronics devices based on field emission lies in the preparation of the field-emission cold cathode with low turn-on and threshold electric field, high field-emission current density, good field-emission stability, long operating life and low cost. Transition metal oxides with good chemical stability, superior antioxidation ability, high temperature resistance, a variety of morphologies, simple preparation and low cost of raw materials etc, are one kind of field emisison materials, which enjoys great potential and vast development prospects.The difficulties faced by the current research for transition metal oxides field emitters are to further reduce the turn-on and threshold electric field, to improve the field emission current density. In this master degree paper, on the basis of summary and analysis of existing work we forward new ideas and new ways to overcome these problems.This dissertation titled “The preparation of kinds of transition metal oxides nanoarray structures and their field emission properties ” systematically summarizes research works of the author during the period of study for a master's degree. Mainly works and results are as following:1. An effective and one-step solvothermal process is developed to fabricate vertically aligned ultra-thin CuO nanosheets with high-quality single crystalline structure on Cu substrate at low temperature of 90 oC. The thickness, densityand size of the prepared nanosheets can be tailored by changing reaction duration and temperature. On the basis of experimental results, a possible mechanism for the formation of the vertically aligned ultra-thin CuO nanosheets is speculated. Moreover, the prepared ultra-thin CuO nanosheets exhibit excellent field emission?FE? properties, a low turn-on electric field of 2.19 V/?m and a high current density of 4.5 mA/cm2 at 8.23 V/?m can be realized from the optimized sample. More importantly, the optimized sample also shows excellent FE stability.2. For the first time, it is proposed an instructive and attractive way to fabricate high performance TiO₂ nanotube arrays field emitters by engineering the annealing atmosphere. Compared with annealing in the atmospheres of Air, Vacuum, and Ar, TiO₂ nanotube arrays annealed in H2 shows optimum field emisison performances involving both a low turn-on field of 2.44V/?m and a remarkable FE stability. The substantially enhanced field emisison properties can be attributed to the introduced oxygen vacancies served as electron donors can substantially improve the conductivity and decrease the work function of TiO₂ nanotube arrays.3. A facile and effective wayto successfully prepare oxygen-deficient ?-Fe₂O₃ nanorod arrays?HNAs? with a pure phase by annealing in an Ar atmosphere at the temperatures of 300-550 oC. It was found that the oxygen-deficient HNAs exhibited an increased oxygen vacancy(Fe²⁺ site) concentration with the increase in annealing temperature. In particular, HNAs annealing at 550 oC exhibit a lowest turn-on field of 1.45 V/?m and a highest emission current density of 3.37 mA/cm2 at 4.86 V/?m. The substantially enhanced field emisison properties are mainly attributed to the increased conductivity and decreased work function resulting from the introduced oxygen vacancies.