High speed 3-dimensional characterisation of graded CdSeTe/CdTe PV devices using a xenon plasma-focused ion beam (PFIB)

3D electron backscatter diffraction (3D EBSD) was carried out using a Xe-PFIB on CdTe thin film solar cells, with a graded CdSeTe (CST) layer. Devices with different ranges of CST and CdTe thickness were investigated. Grain size, texture, coincident site lattice (CSL) boundaries through the film thickness were revealed by 3D EBSD and the elemental composition of the layers was studied using energy dispersive x-ray spectroscopy (EDS). Results show a reduction of (111) texture intensity and grain size when transitioning from CdTe to the graded (CST) layer. The CST has near randomised texture with weak (001) texture. Analysis of CSL boundaries showed that the CST layer in all devices has a lower frequency of Σ3 grain boundaries relative to other types of grain boundaries with a reduction of 15-22% from the CdTe to the CST layer.