Temperature effect on field emission properties and microstructures of polymer-based carbon films

We investigated the field emission properties and resistivity of polymer-based carbon films prepared from poly ethyl-co-phenyl carbyne polymer precursors after treatment at different temperatures. As the heat-treatment temperature increased from 40 to 1200 °C, the emission threshold field decreased from 12.4 to 2.1 Vμm, the emission current density increased from 0.1 to 6.1 mA cm2, and the film resistivity decreased from 108 to 102 Ω cm. The structural changes of the polymer films during the heat-treatment process were analyzed by Raman spectroscopy and atomic force microscopy. Raman analysis of these polymer-based carbon films suggests that the hydrogen content decreased while the sp2 carbon phase increased as the heat-treatment temperature increased. The dependence of the field emission properties of the polymer-based carbon films on the film structures (such as sp3, sp2 phases), film surface morphology and film resistivity is discussed. The enhancement of field emission from polymer-based carbon films was related to the increase of sp2 sp3 ratio, film conductivity, and surface roughness with the heat-treatment temperature.