auger electron spectroscopy (AES)

characterization

1. Auger electron spectroscopy Sharif University of Technology Kamal Asadi Pakdel

2. History Of The Auger spectroscopy Lise Meitner Pierre Auger

3. The Auger Process K L M Vacuum Level Eject core electron Higher electron falls into hole Another higher level electron is ejected to carry away excess energy. Measure kinetic energy of ejected electron. Incident Electron Beam (5 kV) E kinetic = E(K) - E(L) - E(L)

4. KE of Auger electron ~ - E A – E B E C Emitted energy of relaxed electron Energy needed to overcome BE of Auger electron NOTE : KE of Auger electron is not proportional to the primary beam energy Different from XPS Kinetic Energy Of The Auger Electron

5. K L M Source of auger electron Origin of relaxing electron Initial core hole Four main Auger series: KLL, LMM, MNN, NOO As the atomic number increases, the number possible electron transfers are also high.

6. Auger yield

7. electron escape depths

8. In addition, the entire system must be shielded from the earth’s magnetic field AES instrument schematic configuration

9. Electron Gun Properties

10. Electron energy analyzer

11. Electron energy analyzer

12. Cylindrical mirror analyzer(CMA)

13. (HSA) henmispherical scefor alualyser

14. Read-out system

15. Qualitative Identification of Elements Analytical Information Ex: From the differential AES spectrum Ni, Fe and Cr have been identified. Ni Fe Cr

16. Chemical Shift Auger spectra from elemental silicon and oxidized silicon showing the chemical shift which occurs in the oxide

17. Quantification External standard ( 1 Sensitivity factor(2

18. Sensitivity factor of elements

19. Surface Analysis Auger Electron Spectroscopy (AES) Depth Profiling E - Gun Ar + Sputter Gun

20. •The primary electron beam is focussed on the surface and scanned (similarly to SEM). •At each point (pixel), an Auger spectrum is recorded. •Peaks that correspond to a specific element are indentified and their intensity measured. •A colour is assigned to each element •The brightness of colour at each pixel is proportional to the intensity of the corresponding Auger peak. •Result: multicoloured images as chemical element maps . Scanning auger microscopy(SAM):

21. XPS vs. Auger

22. Thanks