Solid-State Emitter Development
Abstract
Theoretical and experimental studies were performed to investigate the feasibility of realizing a new, voltage-activated, nonthermionic cathode proposed by Mumford and Cahay (based on W. Friz s concept). It consists of a heavily n-doped indium phosphide (InP) substrate upon which a layer of thin-film cadmium sulfide (CdS) is grown followed by a layer of lanthanum sulfide (LaS) with a metal grid atop it. Theoretically, only a low voltage (<20 volt) would need to be applied between grid and substrate to produce electron emission from the surface. Under this contract, theoretical analysis of expected self-heating, space-charge, current self-quenching and current-crowding effects was performed. Also, an attempt was made to develop growth techniques for the CdS/LaS layers needed for the structure. CdS thin films were deposited by RF magnetron sputtering and were characterized. Also, a technique was developed to synthesize bulk LaS in the form of a 2-inch-diameter target. The lowest work function measured from this material was 2.6 eV in air. Finally, LaS was grown on Si, glass, and InP by sputtering this target. These films were characterized by X-ray diffraction and X-ray photoelectron and atomic force spectroscopy. Further work will be needed to develop processing techniques for fabricating a testable emitter.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 2002
- Accession Number
- ADA417857
Entities
People
- Marc Cahay
- Punit Boolchand
Organizations
- University of Cincinnati