Novel sputtering method for Pd-Al₂O₃ UV transparent conductive coatings

A thin film structure of Pd-Al₂O₃ was developed as a signal plate for ultraviolet (UV) vidicon television picture tubes. The Pd-Al₂O₃ films were deposited using a novel sputtering method. The 20 angstroms thick Pd layer served as a conducting plate while the 30-50 angstroms thick Al₂O₃ layer functioned as a transparent protective passivation film. The obtained signal plates had a sheet resistance of 2.5 kΩ and a transparency coefficient of 71% at a wavelength of 250 nm, which is suitable for near-UV applications. The main advantage of vidicons equipped with such signal plates is its less than 0.05 nA dark current.