CVD diamond: a novel high γ-coating for plasma display panels?

Abstract

Minimization of the firing voltage of plasma display panels requires electrode coatings with high ion-induced secondary electron emission coefficients (γ-coefficients). This paper discusses the methodology of Paschen-curve-based γ-measurements and compares measured γ-coefficients of MgO, the standard material for this application, with data measured for CVD diamond of various thicknesses, a-C:H and ta-C films grown on glass. Ne, Ar and Xe discharges are investigated. The negative electron affinity (NEA) of H-terminated CVD diamond is shown to lead to high γ-values, stable operation and low plasma firing voltages that rival or even surpass those of the best quality MgO(111) single crystals with the advantage of diamond being less sensitive to panel processing conditions. Replacing the H-termination of diamond by positive electron affinity (PEA) O-termination results in a dramatic increase of the firing voltage, thus demonstrating the importance of the electron affinity for ion-induced secondary electron emission. Diamond is found to be particularly interesting for high Xe panel fillings. The γ-coefficients of DLC- and ta-C layers are significantly lower and show considerable instability and degradation over time. The advantages and drawbacks of diamond as a PDP cell coating are discussed.