Horiba GD-Profiler-2: Glow Discharge Optical Emission Spectrometer
Glow Discharge Optical Emission Spectrometry uses a high-power RF plasma to sputter a crater into nearly any material, and measures the atomic emission of the sputtered material as it is excited within the plasma. This technique therefore gives depth-resolved elemental analysis up to ~1 mm deep with down to 10 nm resolution. Atomic emission lines for 40 elements are collected simultaneously using a high-resolution Nitrogen purged polychromator. These elements are highlighted in the graphic below.
The sputtering source is very versatile and works with nearly any sample. A 4 mm diameter anode is standard, but a 2 mm option is also available. Under high-power operation, a crater ~100 microns deep is sputtered in less than 5 minutes. The source can additionally operate in a pulsed mode for higher resolution or for fragile samples (such as those with glass substrates). The only restrictions on samples are that they must be flat, rigid, and large enough to cover the anode.
The GD plasma can also be used as a sample preparation tool for SEM. To accentuate material features with otherwise low contrast or fragile features that might be destroyed by traditional polishing methods, the slight variations in GD sputtering rates for different materials and even crystal domains of a homogenous material can be used to increase contrast.
For an example of quantitative GDOES for thin film solar cell applications, please see:
Clark, James A., et al. “Evolution of Morphology and Composition during Annealing and Selenization in Solution-Processed Cu2ZnSn (S, Se) 4.” Chemistry of Materials 29.21 (2017): 9328-9339.