AES, EDX, SIMS, XPS
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AES (Auger Electron Spectroskopy) is a very sensitive method for surface analyses. The ecitation is effected by an electron beam and the emitted Auger electrons are then detected for analyses.
 

Characteristics of  AES are:

  • A hight lateral resolution due to thin beam diameter of  approximately 10 nm → it is possible to perform mapping of the chemical composition of the surface with Scanning Auger Microscopy (SAM)

  • Auger electrons are emitted of surface near region. The depth of the received information is about 2,5 – 10 nm. Therefore, AES is very applicable for the investigation of thin surface films.

  • The atomic resolution is about 0,5 – 1 At%

  • Depth profiles to a depth of up to 500 nm can be taken by sputtering with an ion gun (e.g. Argon ions).

Normally, elements from Lithium upwards can be detected. Very seldom it is also possible to get information about the chemical bond.


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EDX (Energy Dispersive X-Ray Analysis) is an often used method for determination of the chemical composition of thicker samples (not surface sensitive). Excitation is effected with an electron beam. For analysis, the emitted x-rays are detected.
 

Characteristics for EDX are:

  • limited lateral resolution due to an electron beam diameter of approximately 1 – 10 µm  (depending on the acceleration voltage)

  • Information are received from a depth of absolute 1 – 3 µm (also depending on the acceleration voltage). Therefore it is not possible to investigate thin surface layers.

  • The atomic resolution is approximately 0,5 – 1 At%

  • It is only possible to detect elements but no chemical bonding


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SIMS (Secondary Ion Mass Spectroskopy) is a very surface sensitive analysis method. Two different methods are used. TOF-SIMS (Time Of Flight) and D-SIMS (dynamic). It is possible to detect elements in the ppm-range with TOF-SIMS and in the ppb-range with D-SIMS (currently not available for us). For analysis, the surface is sputtered with ions (Ga, Cs, O2, In) and the emitted ions are detected. Therefore, a change of the chemical compositions occurs on the surface.
  

Characteristics of TOF-SIMS are:

  • Good lateral resolution due to a beam diameter of approximately 100 nm

  • The lowest emitted ions are from a depth of about 1,5 nm

  • The atomic resolution is within the ppm range

  • EAll elements can be detected (inclusive hydrogen). Furthermore, it is possible to receive information of the chemical bonding by comparative measurement of standards

  • Sputter profiles can be performed to a depzh of approximately 3 – 4 µm


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XPS (X-Ray Photoelectron Spectroskopy, also named ESCA = Electron Spectroskopy for Chemical Analyses) is a surface sensitive analyses method. Excitation is affected by a x-ray or photon beam. For analysis the emitted electrons are detected..
 

Characteristics of  XPS are:

  • A limited resolution due to a beam diameter of approximately 10 µm of the x-ray or photon beam

  • Emitted electrons are from a depth of aproximately 5 – 10 nm

  • Atomic resolution is about 0,5 – 1 At%

  • By sputtering with inert ions (e.g. argon) surface layers can be removed and depth profiles can be performed to a depth of up to 500 nm

  • It si possible to detect elements (from lithium upwards) and it is also possible to receive information about chemical bonding.

 

 
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Technics for surface analysis