Chiou-Mei Chen

Effects of Supercritical Fluids Activation on Carbon Nanotube Field Emitters

This paper proposes a novel method to enhance the emission characteristics of carbon nanotubes (CNTs). It is extremely possible for CNTs to adsorb moisture and other contaminants during the fabrication processes, leading to the degraded field emission characteristics. In this work, CNT emitters are activated with commonly used heating process and supercritical carbon dioxide (SCCO2) fluids technology for removing adsorbed residue moisture. Experimental results have demonstrated that the electrical stability and field emission enhancement of CNT emitters are effectively achieved by the SCCO2 fluids treatment compared to the heating process, due to the minimization of residuary moisture in CNTs

Activation of Carbon Nanotube Emitters by Using Supercritical Carbon Dioxide Fluids with Propyl Alcohol

Carbon nanotubes CNTs as electric field emitters have especially received great attention, due to their high mechanical strength and chemical stability coupled with very high aspect ratios, leading to extremely strong local fields. 1-3 These attractive properties of CNTs make them extraordinary materials for field emission display FED applications. 4 For most electrical applications, the nanotubes need to be produced free of impurities, contamination, and minimized moisture adsorption. The two major sources of contamination in the growth of CNTs, including amorphous carbon and extraneous metal catalyst, can be eliminated by the cautious use of etching gases and by optimizing the catalyst formula, respectively. 5,6 However, few studies have been reported for the efficient drying methods to minimize residual moisture in the nanostructure CNTs. In general, a trace of residual moisture in electronic devices tends to degrade electrical performance and cause electrical instability. As for the field emission characteristics of CNTs, experimental work really focused on the study of the moisture adsoption effect also has been lacking so far. Therefore, in this work the influence of residual moisture on the field emission of CNTs is investigated first. In addition, the application of supercritical carbon dioxide SCCO2 fluids is proposed to activate CNT emitters, minimizing residual moisture uptake with no possible damage to the CNTs. The CO2-based processing is attractive because of its environmental compatibility, as it is nontoxic, nonflammable, and unreactive under most conditions. 7 SCCO2 is similar to liquid CO2 since it also dissolves methanol. Additionally, it possesses gas-like properties of diffusivity and viscosity that allow it to remove solvents from the narrow spaces between micro- and nanotructure surfaces. 8 Also, the extremely low surface tension of SCCO2 can account for its negligible effect i.e., extremely low damage on the morphology and microstructures. 9-11

Effect of Supercritical Fluids on Field Emission from Carbon Nanotubes

This paper proposes a novel method to enhance the emission characteristics of carbon nanotubes (CNTs). It is extremely possible for CNTs to adsorb moisture and other contaminants during the fabrication processes, leading to the degraded field emission characteristics. In this work, CNT emitters are activated with commonly used heating process and supercritical carbon dioxide (SCCO2) fluids technology for removing adsorbed residue moisture. Experimental results have demonstrated that the electrical stability and field emission enhancement of CNT emitters are effectively achieved by the SCCO2fluids treatment compared to the heating process, due to the minimization of residuary moisture in CNTs.