Surface properties of metal-nitride and metal-carbide films deposited on Nb for radio-frequency superconductivity
Various effects occur which can prevent attainment of the high Q's and/or the high gradient fields necessary for the operation of radio-frequency (rf) superconducting cavities. One of these effects, multipactor, both causes the cavity to detune during filling due to resonant secondary electron emission at the cavity walls, and lowers the quality factor (Q) by dissipative processes. TiN deposited onto the high-field regions of room-temperature Al cavities has been used at the Stanford Linear Accelerator Center to successfully reduce multipactor in the past. We have therefore studied TiN and its companion materials, NbN, NbC, and TiC, all on Nb substrates under several realistic conditions: (1) as-deposited, (2) exposed to air, and (3) electron bombarded. The studied films (up to 14-nm thickness) were sputter deposited onto sputter-cleaned Nb substrates. Results indicate that all the materials tested gave substantially the same results. The maximum secondary electron yields for as-deposited films were reduced to nearly the preoxidized values after electron bombardment (2--3 x 10/sup 17/ electrons cm/sup -2/ in the case of NbN and NbC). X-ray photoelectron spectroscopy analysis showed that the oxides (e.g., TiO/sub 2/ in the case of TiN films) formed during air exposure were slightly reduced (converted to lower oxides) by the electron-beam exposure. Auger electron spectroscopy (AES) showed a slight reduction in the surface O concentration following beam exposure. These results suggest that the chemical nature of top surface layers is responsible for the substantial changes in secondary electron yield observed upon electron-beam exposures and that AES does not reflect this change strongly because of the difficulty in extracting chemical (versus elemental) information from AES.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- DOE Contract Number:
- AC03-76SF00515
- OSTI ID:
- 6751899
- Journal Information:
- J. Appl. Phys.; (United States), Vol. 61:3
- Country of Publication:
- United States
- Language:
- English
Similar Records
Properties of thin antimultipactor TiN and Cr/sub 2/O/sub 3/ coatings for klystron windows
An ultrahigh vacuum, magnetron sputtering system for the growth and analysis of nitride superlattices
Related Subjects
GENERAL PHYSICS
36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
NIOBIUM CARBIDES
ELECTRON COLLISIONS
OXIDATION
SECONDARY EMISSION
NIOBIUM NITRIDES
SUPERCONDUCTING CAVITY RESONATORS
OPERATION
QUALITY FACTOR
TITANIUM CARBIDES
TITANIUM NITRIDES
AUGER ELECTRON SPECTROSCOPY
NIOBIUM
PHOTOELECTRON SPECTROSCOPY
SPUTTERING
STANFORD LINEAR ACCELERATOR CENTER
SURFACE CLEANING
SURFACE CONTAMINATION
CARBIDES
CARBON COMPOUNDS
CAVITY RESONATORS
CHEMICAL REACTIONS
CLEANING
COLLISIONS
CONTAMINATION
ELECTRON SPECTROSCOPY
ELECTRONIC EQUIPMENT
ELEMENTS
EMISSION
EQUIPMENT
METALS
NATIONAL ORGANIZATIONS
NIOBIUM COMPOUNDS
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
REFRACTORY METAL COMPOUNDS
RESONATORS
SPECTROSCOPY
SUPERCONDUCTING DEVICES
SURFACE FINISHING
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
US DOE
US ERDA
US ORGANIZATIONS
640301* - Atomic
Molecular & Chemical Physics- Beams & their Reactions
360204 - Ceramics
Cermets
& Refractories- Physical Properties
656100 - Condensed Matter Physics- Superconductivity
420201 - Engineering- Cryogenic Equipment & Devices