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Low work function, stable thin films

United States Patent

December 19, 2000
View the Complete Patent at the US Patent & Trademark Office
Lawrence Livermore National Laboratory - Visit the Industrial Partnerships Office Website
Generation of low work function, stable compound thin films by laser ablation. Compound thin films with low work function can be synthesized by simultaneously laser ablating silicon, for example, and thermal evaporating an alkali metal into an oxygen environment. For example, the compound thin film may be composed of Si/Cs/O. The work functions of the thin films can be varied by changing the silicon/alkali metal/oxygen ratio. Low work functions of the compound thin films deposited on silicon substrates were confirmed by ultraviolet photoelectron spectroscopy (UPS). The compound thin films are stable up to C. as measured by x-ray photoelectron spectroscopy (XPS). Tests have established that for certain chemical compositions and annealing temperatures of the compound thin films, negative electron affinity (NEA) was detected. The low work function, stable compound thin films can be utilized in solar cells, field emission flat panel displays, electron guns, and cold cathode electron guns.
Dinh; Long N. (Concord, CA), McLean, II; William (Oakland, CA), Balooch; Mehdi (Berkeley, CA), Fehring, Jr.; Edward J. (Dublin, CA), Schildbach; Marcus A. (Livermore, CA)
The Regents of the University of California (Oakland, CA)
09/ 080,096
May 18, 1998
The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the United States Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.