Electron field emission from tetrahedral amorphous carbon films with multilayer structure

Abstract

A multilayer structure with alternating metal and semiconductor layers is proposed to occur in tetrahedral amorphous carbon (ta-C) films prepared by using an intermittent layer-by-layer deposition method. In this model, the multilayers can be represented as A/B/A/B/…/A/B/A stacks, in which A is considered to be a semimetallic sp2-rich graphite-like layer with B being a semiconducting sp3-rich diamond-like layer. According to the proposed structural model, the electron field emission properties of the ta-C multilayers that could be modulated by adjusting the total number of layers, layer thickness and sp3 content of each layer have been predicted. Correspondingly, three kinds of ta-C multilayers were designed and deposited to confirm this model by enabling us to measure the electron field emission properties. Agreement between the prediction and the experimental results has been observed. It was found that field emission from ta-C multilayers can be optimized by changing the number of layers, layer thickness and sp3 content of each layer. In our experiments, a threshold electric field (Eth) as low as ∼5 V/μm has been obtained for field emission from ta-C multilayers with a total of 20 layers and with a 10 nm layer thickness.