Surface production of negative hydrogen ions
Production of H{sup {minus}} ions on hydrogenated and cesiated semiconductor and metal surfaces has been investigated. An H{sup {minus}} ion is formed when an electron tunnels from a target surface to an escaping hydrogen atom. The efficiency of this process is dependent on target work function and hydrogen escape velocity. The motion of the hydrogen atom moving from the surface was realized by sputtering and backscattering. The sputtering of adsorbed hydrogen by Cs{sup +} ion bombardment was studied. H{sup {minus}}, Mo{sup {minus}}, and e{sup {minus}} were sputtered from a polycrystalline molybdenum cathode by Cs{sup +} ions in the energy range 150 to 1000 eV. The H{sup {minus}} ions parallel energy distribution is Maxwellian. For optimum coverage, the temperature varies from 0.60% to 0.32% of the bombarding energy for Cs{sup +} ion energies of 250 and 1000 eV, respectively. The H{sup {minus}} ion yield, defined as the number of H{sup {minus}} ions produced per incident Cs{sup +} ion, reaches a maximum of 0.41 for a Cs{sup +} ion bombarding energy of 750 eV. The yield goes to zero for a Cs{sup +} threshold energy of 120 eV. This indicates a binding energy of 3 eV for the hydrogen to the target surface. H{sup {minus}} ions were also formed by simultaneously bombarding a ruthenium target with H{sub 2}{sup +} and Cs{sup +} ions. The H{sup {minus}} ion energy distribution consisted of three components due to Cs{sup +} sputtering, H{sub 2}{sup +} sputtering, and reflection of hydrogen ions. The production of H{sup {minus}} ions was also investigated by backscattering thermal hydrogen atoms from partially cesiated polycrystalline molybdenum and (100) n-type silicon targets. The experimental results are compared with a theoretical model.
- Research Organization:
- Stevens Inst. of Tech., Hoboken, NJ (USA)
- OSTI ID:
- 6836296
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
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75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CESIUM IONS
CHARGED PARTICLES
DATA
DATA ANALYSIS
ELEMENTS
EXPERIMENTAL DATA
HYDROGEN IONS
INFORMATION
IONS
MATERIALS
MEASURING INSTRUMENTS
MEASURING METHODS
METALS
NUMERICAL DATA
PLATINUM METALS
PRODUCTION
RUTHENIUM
SEMICONDUCTOR MATERIALS
SPUTTERING
SURFACE PROPERTIES
TRANSITION ELEMENTS
TUNNELING