Comparative study of laser induced breakdown spectroscopy and secondary ion mass spectrometry applied to dc magnetron sputtered as-grown copper indium diselenide (CIS)

The University of Salford has led the way in the fundamental research that has underpinned the development of thin film copper indium diselenide (CIS) based photovoltaics. These devices have demonstrated exceptional energy conversion efficiencies (>19%) and a high tolerance to radiation damage and are thus leading researchers towards the 20% efficiency barrier. Conventional CIS thin film growth processes require a post-selenisation step to incorporate Se into the as-grown material. This helps to achieve stoichometry, improves the crystallinity, controls the defect structure and also can be used to convert the semiconductor type. This paper will report the use of pulsed dc magnetron sputtering from a CIS powder target. This approach has resulted in as–grown stoichiometric thin films consisting of pinhole free, densely packed grains. An important consideration in the thin film growth of complex materials is that stoichiometry is maintained throughout the film. Conventionally, secondary ion mass spectrometry (SIMS) is used to depth profile thin films but it has been reported that laser induced breakdown spectrometry (LIBS) can also be used. W e will report the initial results comparing and contrasting these two techniques and show that LIBS can produce meaningful data.