Field Emission from Vertically Aligned Silicon Nanowires

摘要

There has been a growth of interest in synthesis of well-organized one-dimension nanomaterials, such as carbon nanotubes (CNTs) [1], Si nanowires (SiNWs) [2], and Si carbide nanowires [3] for field emission applications. Among them, SiNWs are of particular interest due to their well-understood electronic property and to the fact that Si based field emission devices have possibility of integration with various monolithic circuits. In this study, we report a method of using a self-assembled nanomask, together with reactive ion etching for synthesis of vertically aligned SiNWs. The SiNWs thus fabricated have found to exhibit excellent field emission property and also for the first time, arrays of SiNW-based field emission microtriode have been realized. The technique is easily employed to fabricate arrays of SiNW-based field emission microtriodes. In the present work, Au-Ag nanoparticles are used as nanomasks for Si nanowires fabrication. The Au-Ag nanoparticles were obtained by employed a thermal annealing technique. Au-Ag alloy film deposited on Si substrate is annealed in H{sub}2 ambient at a temperature of 750°C. Fig. 1 is the typical scanning electron micrograph (SEM) image of the nanoparticles, showing a uniform distribution. EDX analysis results demonstrated that the nanoparticles are of Au-Ag composition. The diameter of the nanoparticles is fallen in a range of 50-100 nm. Then, the SiNWs were fabricated through a dry etching processing in an inductively coupled plasma (ICP) system. Mixture gases of C{sub}4F{sub}8 and SF{sub}6 were used as etchant. Fig. 2 is a typical SEM of the silicon nanowire arrays, showing the uniform vertically aligned silicon nanowire arrays. The diameter of the Si nanowries is ranges from 50 to 100 nm, the height is ～1.1μm.