Nonthermionic Cathode Development
Abstract
This project focused on developing methods for fabrication of nonthermionic cold cathodes based on a lattice-matched material system consisting of a conducting substrate (source of electrons), a wide-bandgap semiconductor (conduction band closer to the vacuum level), and a low-work function material (to facilitate high emission of electrons). A material system fulfilling these requirements was found in indium phosphide (InP) as a substrate, cadmium sulfide (CdS) as the wide-bandgap semiconductor, and lanthanum monosulfide (LaS) as the low-work-function material. Growth of CdS was conducted using three methods: low-energy, ion-assisted growth (LEIAG); solid-source molecular beam epitaxy (SS-MSB); and gas-source MBE (GS-MBE). In situ reflection, high-energy electron diffraction (RHEED) indicated that growth of the desired epitaxial cubic-CdS occurred over a wide range of temperatures. However, surface decoration of hydrogen during GS-MBE resulted in initiation of hexagonal CdS phase as the layer grew thicker. Auger electron microscopy (AES) depth profiling showed stoichiometric composition of CdS and abrupt CdS/InP interfaces, while atomic force microscopy (AFM) showed small surface roughness, depending on the deposition method used. Thin layers of LaS were also grown on CdS. Further work will be needed to develop processing techniques for a testable electron emitter.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2002
- Accession Number
- ADA419083
Entities
People
- M. A. Hasan
Organizations
- University of North Carolina at Charlotte