Chemical concentration depth profiles of thick layers

GDOES instrument from Spectruma.
© Fraunhofer IST, Kirsten Schiffmann
GDOES instrument from Spectruma.

Glow discharge spectroscopy GDOES

Glow Discharge Optical Emission Spectroscopy (GDOES) or glow discharge spectroscopy is a technique for determining chemical composition as a function of depth for film thicknesses from a few 100 nm to a few hundred micrometers. In this process, an Ar plasma is ignited over the surface of the sample and the material is ablated at a relatively high rate. The ablated atoms are excited and therefore emit light in the visible range, which is measured with a variety of spectrometers and the concentration of the elements is determined. 

Areas of application

Fields of application: Routine examinations of nitriding, boriding or carburizing coatings, electroplating coatings, spray coatings, inorganic paints, etc.

Advantages:

  • Fast removal of even very thick layers within minutes
  • Detection limits in the range 0.01%

Limitations: 

  • Low spatial resolution (5 mm)
  • No curved specimens
  • Reduced depth resolution due to crater edge effects. 
  • Calibration effort
Glimmentladungsspektroskopie GDOES Tiefenprofil eines carbonnitrierten Stahls: GDOES-Tiefenprofil eines carbonitrierten Stahls zeigt die Tiefenverteilung von Kohlenstoff und Stickstoff auf einer logarithmischen Tiefenskala.
© Fraunhofer IST

GDOES depth profile of a carbonitrided steel shows the depth distribution of carbon and nitrogen on a logarithmic depth scale.