Surface Science Lab. --- A laboratory dedicated mainly to the study of the surfaces of superconducting radio frequency cavities and the support of other relevant activities at JLab.

Superconducting Radio Frequency (SRF) cavities are the indispensable parts of the CEBAF accelerator. The performance of SRF cavities relies critically on surfaces properties. A Surface Science Laboratory (SSL) has been established to study the surfaces of SRF cavities in general and Nb surfaces in particular. A better understanding of Nb surfaces prepared by various techniques and procedures in terms of texture, morphology, oxide structure, defect, impurity, and level of tolerable contamination will enable us to make cavities with the highest performance and reproducibility at the lowest possible cost.

The SSL has all the instruments for doing surface observation and measurement on Nb, including sample preparation. Some surface instruments are quite unique. Each instrument is explained briefly below:

Scanning Auger Microscope (SAM)

*: Surface composition determination (0.3% accuracy except H and He).

*: Depth profile

*: Surface composition mapping

*: In-situ heat treatment (-35 ~ 1000 ^oC)

*: Scanning Electron Microscope

*: Can be extended to include X-ray Photoelectron Spectroscope

Scanning Field Emission Microscope (SFEM)

*: Large scanning size d=25mm

*: Spatial resolution 2.5 mm

*: Routine operation electric field up to 140 MV/m

*: In-situ heat treatment chamber

*: Coupled with SEM and EDX

Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Analysis (EDX)

*: Morphology and Topography (Surface and Cross-section)

*: Magnification can be up to 100,000 routinely (a few nanometer resolution)

*: Can detect all elements with mass heavier than Boron

*: Probe depth ~ 1-5 micrometer

*: Detection limit ~ 0.5% atm weight

*: Can be extended to include the measurement of secondary electron yield

Secondary Ion Mass Spectrometry (SIMS)

*: Surface composition analysis (ppm or ppb)

*: Can detect all elements and their isotopes including hydrogen

*: Depth profile

Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), and Scanning Transmission Electron Microscope (STEM) system

Used for observing dislocation, grain structure, interstitial atom, stacking fault, secondary phase, grain orientation, crystal structure, texture, morphology, etc. (very useful for thin film microstructure analysis).

*: Accelerating voltage 100 kV

*: Magnification up to 800,000 X

*: Point to point resolution 0.3 nm

*: Lattice resolution 0.14 nm

High Precision & Large Scan Area Profiler

*: Vertical resolution of 0.1 nm with a guaranteed repeatability of 0.75 nm.

*: Scanning area of 80X200 mm².

*: Three-dimensional plots

Metallographic Optical Microscope (MOM)

*: Computer-controlled image caption and processing

*: Magnification up to 2,000X

*: Resolution ~ 150 nm

Sample Preparation Room

This sample preparation room is one of the best-equipped sample preparation facilities in this area. It can do all sample preparation required by the SSL except ion milling (will be acquired).