Peak-fitting Process – Examples
Examples: Si (2p), C (1s), and Mg (2p) spectra
Chemical States from Silicon – Si (2p) electrons
Raw Spectrum of Silicon “2p” type electrons from a Native Oxide on a Silicon Wafer.
Measure Survey Spectra First, Then Measure Chemical State Spectra
Survey Spectra use low energy resolution settings. As a result we can not see the different Chemical State signals until we change the instrument settings to give high energy resolution settings.
Next: If sample was Non-Conductive, then correct all spectra by using Charge Referencing method.
Then: Peak-fit each Chemical State Spectra.
Peak-fitting Steps Used to Peak-fit a Raw Si (2p) Spectrum – from a Native Oxide of Silicon
Raw Spectra of Pure Silicone and Silicon Dioxide
Result of Peak-fitting Spectrum – No Chemical State (species) Assignments Yet
How to Assign Chemical States to Each Peak in a Peak-fitted Spectrum
This spectrum shows the positions of the different Chemical States that exist in the Native Oxide of Silicon.
This Chart Shows Chemical Shifts and Chemical State BEs for Various Silicone Chemicals
Chemical States from Carbon – C (1s) electrons
Raw Spectrum of Carbon “1s” type electrons from acetone washed Mylar (PET)
Chemical States from Magnesium – Mg (2p) electrons
Chemical State Spectra Variables to Consider
- Atom %vs PE settings
- Calibration Check done recently?
- C 1s FWHM as charge indicator
- Charge induced broadening
- Charge referencing
- Charging artefacts
- Chemical shifts
- Chemical states
- Data collection parameters
- Data interpretation
- Data quality
- Differential charging
- Dwell time
- Number of data points
- Pass energy vs FWHM
- Peak area ratios
- Peak assignment
- Peak fitting
- Peak overlaps
- Reference BEs used
- Reference FWHMs
- Reference spectra
- Sample degradation ?
- Sample preparation affects
- S/N vs # of scans
- Spectrum features
- Spectrum width
- Step size
- Thickness calculations