| 초록 |
Carbon nanotubes (CNTs) have drawn much attraction as the most promising field emitter material studied ever due to their excellent electrical conductivity and superior chemical and mechanical stability as well as their high aspect ratios. The screen-printing technology using photosensitive CNT paste has been widely adopted to form the large area field emission devices because they are characteristic of low cost, uncomplicated processes, uniform emission sites, and large-area production capability. In the screen-printing method, the CNT paste, which is the most major material in manufacturing the field emission devices using this method, has to be designed mainly in consideration of dispersion, printability, adhesion, conductivity, population of CNT emitters, etc. This study carried out a parametric approach to formulating the photo-sensitive CNT paste by changing the amounts of conductive fillers and their particle sizes. The morphologies and emission properties of the CNT pastes with different mixing ratios of micrometer-size and nanometer-size fillers were investigated. We successfully fabricated CNT emitter dot arrays of 10 μm diameter with excellent field emission properties using photosensitive CNT paste. Among many combinations of µm-size and nm-size conductive fillers, the mixing ratio of 3:1 produced the best J-E curve. Optimum is the filler content of 5% under the mixing ratio of 3:1. The 5% filler paste showed the emission uniformity 2% higher than no filler one. Optimum CNT paste which showed excellent emission property had vertically well-aligned CNTs on the surface after surface treatment using an adhesive tape. The amount and morphology of fillers would have a considerable effect on the shape, processing stability, and field emission characteristics of CNT emitter dots. We believe that the addition of a small amount of nm-size fillers seems to be helpful to improve the field emission characteristics of the photosensitive CNT paste. |
