화학공학소재연구정보센터
Journal of Vacuum Science & Technology B, Vol.26, No.2, 764-769, 2008
Field emission characteristics of a lanthanum monosulfide cold cathode array fabricated using microelectromechanical systems technology
Using microelectromechanical systems technology, an array of cold cathodes was fabricated by pulsed laser deposition of chemically and thermally stable lanthanum monosulfide (LaS) thin film anode and cathode contacts. The latter were defined via etching and processing of two different pieces of (100) Si wafers separated via a highly resistive sputter deposited aluminum nitride (A1N) layer, whose thickness was used to control the anode to cathode spacing. The top and bottom Si wafers were aligned and glued together using high temperature, vacuum compatible epoxy. Field emission characteristics were recorded in a vacuum chamber with a base pressure less than 10(-7) Torr. An average electric field threshold for Fowler-Nordheim field emission in the range of 100 V/mu m was measured. The largest emission current measured was about 5 x 10(-7) A, above which thermal runaway occurred, leading to a failure of the cathode. The failure mechanism is analyzed in terms of a patchwork field emission model from the LaS thin film reported recently. Suggestions for improvements in the cathode design are discussed. (c) 2008 American Vacuum Society.