Study On Field Emission Properties Of Nickle-Based Nanocones Arrays

Field emission display (FED) with excellent display properties has been studied widely. The key point to FED is the fabrication of cold emission cathode. High cost accompanied with the complex micro-manufacturing technologies is a huge barrier for the industrial manufacturing of the popular Spindt-FED and CNT-FED cathodes. Therefore, a simple directional electrocrystallization method by which Ni-based nanocones filed emission arrays(FEAs) are fabricated is carried out by our lab to solve these problems. This simple method with low cost and wide availability on conductor substrate has a very bright prospect on FED cathode fabrication.In view of this potential, basic research on the fabrication and field emission properties of Ni-based FEAs are carried out. Ni nanocones arrays fabricated by directional electrocrystallization are sharp, orderly, erect and compact. The density of nanocones is in order of 109/cm2 and the minimum of apical angle is only 31.2°. Various effects on morphology of Ni-based nanocones arrays are studied by scanning electron microscope. Comparing with Cu substrate, glass slide with sputtered Cu film is more accessible for growing a sharper and orderly Ni nanocones arrays with less burrs. The deposition parameters such as current density and deposition time are dominant in the morphology of arrays.In addition, to decrease the work function and prevent the oxidation and failure induced by ion bombardment, AlN films are sputtered on arrays with different thickness, from 10nm to 200nm. With the increase of the thickness, the sharpness of Ni-based nanocones arrays is decreased.Ni-based nanocones arrays as-fabricated all have good emission performance. A very low turn-on field 0.38V/μm of Ni-based FEAs fabricated on Cu substrate is achieved. Since field emission cathode would be finally used on glass substrate, the research emphasized on Ni-based FEAs fabricated on Cu-buffered glass slide substrate. The minimum of their turn-on field is about 5V/μm with a large emission current, about 200μA. Huge effects on emission properties of morphology varied with deposition time and sputtered AlN film are revealed. The emission performance of Ni nanocones arrays worsens because the sharpness and order are decreasing with the deposition time prolonging. Also, in the experiment, the sputtered AlN films with a too large thickness that electrons are difficult to go through are harmful to the emission performance of Ni nanocones arrays. Combing the research of morphology and field emission properties, a method is proposed to control and optimize the morphology of Ni nanocones arrays to achieve a better emission performance by substrate selection, electrodeposition parameters configuration and AlN film sputtering with suitable thickness. The optimum of electrocrystallization parameters on Cu-buffered glass slide is, the temperature of solution T=60°C, pH=4.0, the current density j=2.0A/dm2 and the time t=112s.