1. XPS and SIMS
MSN 506 Notes

2. X-Ray Photoelectron Spectroscopy

3. Photoelectron Emission
X-Rays kick a core shell electron out

4. XPS data
Signal mainly comes from few nanometers of the surface

5. XPS data
Tails associated with peaks are not random bu are due to loss of electron energy through scattering

6. XPS data
Absolute positions of peaks are not always the same because of accumulated surface charge

7. Chemical Bonds perturb energies
Bonding states of nuclei can be estimated by looking at chemical shifts

8. SIMS Secondary Ion Mass Spectrometer
Primary beam species useful in SIMS include Cs+, O2+, O , Ar+, and Ga+ at energies between 1 and 30 keV. Primary ions are implanted and mix with sample atoms to depths of 1 to 10 nm.
Sputter rates in typical SIMS experiments vary between 0.5 and 5 nm/s. Sputter rates depend on primary beam intensity, sample material, and crystal orientation.
The sputter yield is the ratio of the number of atoms sputtered to the number of impinging primary ions. Typical SIMS sputter yields fall in a range from 5 and 15.

9. SIMS Secondary Ion Mass Spectrometer

10. Depth Profiling
Valuable tool for depth profiling of material layers or interdiffused elements