Capabilities and limitations of LA-ICP-MS for depth resolved analysis of CdTe photovoltaic devices†
The analytical potential of ArF* excimer Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is investigated for fast qualitative depth profile analysis of multi-layer CdTe photovoltaic (PV) devices. Critical parameters (e.g. laser fluence and laser repetition rate) are evaluated and optimized to reduce the aerosol mixing from consecutive laser shots and to achieve a low penetration rate. As a result, a high depth resolution (10 s of nm) is demonstrated through the analyses of superficial and embedded coatings. For instance, a layer with a thickness of 100 nm at a depth of 3 μm is successfully measured. Moreover, qualitative profiles of major and minor elements obtained by LA-ICP-MS are validated using reference techniques such as Secondary Ion Mass Spectrometry (SIMS) or Glow Discharge Time of Flight Mass Spectrometry (GD-TOFMS). Additionally, the shape and morphology of the laser-induced craters, after different numbers of laser shots, are investigated using mechanical profilometry and Atomic Force Microscopy (AFM), respectively.