Surface-conduction Electron-emission Mechanism Of Granular Films

Surface-conduction Electron-emitter Display(SED) is a kind of field emission display, which has obvious advantage in comprehensive energy consumption, reaction speed and so on over other flat panel displays. However, the emission efficiency and longevity of cathode electron emission array of Surface-Conduction electron are the most fundamental factors that hold its expansion, due to the shortage of study in device cathode emitter materials and indeterminate electron emission mechanism. Therefore, the granular films were selected as the surface-conduction electron emission cathode films and its electron emission mechanism was reported.C-Ti granular films and Al-AlN granular films were prepared by means of magnetron sputtering technique, the principle device of surface-conduction electron emission display is manufactured by the photolithography process. This paper studies effects of preparation process of different granular films, device structure, electric forming environment, applied electric field mode and granular film materials on the electrical properties of the SED devices. According to the evolution of the electrical properties and related theory, the granular films electron emission mechanism was discussed. The main results are as follows.The granular films of different thickness were prepared as the cathode emission films. Symmetric triangular wave voltages of different magnitudes were applied to electroform the device. It is shown that the turn-on voltage of the 69 nm-thick-film was 32 V, with the emission efficiency reaching its maximum at 33V, while the turn-on voltage of a 855nm-thick-film was 15 V, with the maximum rate appearing at 23V.The electroforming processes were conducted in vacuum and air respectively. The results shown that, when the amplitude of the cathode voltage is 45 V, the device has the highest electron emission efficiency. However, as the electroforming of granular film is performed in air,its emission stability is poor due to the film affected by air oxidation despite its electron emission efficiency is high.The effect of the different applied electric field mode on the electrical properties was conducted.It is shown that the electron emission efficiency reach the highest value while loading cathode voltage of 39V on electrode without bias voltage on substrate or loading cathode voltage of 36V on electrode with -3V on substrate or loading cathode voltage of 34V on electrode with -5V on substrate.We can find that the electron emission efficiency increased as the negative voltage on substrate increased obviously.Different cathode materials of the Al-AlN and Ti-C granular films were prepared to research the influence on the electron emission characteristics.The SED device base on the C-Ti granular films fabricated on the silicon substrate is unable to electroforming and then to emit electron,although the device based on Al-AlN could be electroformed under the same conditions, The main clauses were attributed to the silicon substrate, which has changed the granular films properties and also the device’s thermal structure.Combining electron emission (conduction) current characteristics under different conditions and the F-N theory followed by the field emission electron, we could prove that the granular films surface electron emission current is a part of the device current,and the emission current and device voltage are followed the F-N theory, which indicates that surface-conduction electron emission is a field emission.The granular films conduction current and device voltage did not follow F-N theory, because part of the device current transmitted through the conductive network of the granular films, and part of the current tunneled in the nano-gaps through the field emission.