Scanning Auger microprobe studies of ball cratered CdS/CuInSe2 solar cells

CdS/CuInSe2 solar cell films are typically several micrometers thick. Composition profiles of these films are usually carried out on fracture cross sections by scanning Auger microscopy or by recording Auger spectra during ion milling. For fracture cross sections, the depth resolution depends on the electron beam diameter and the roughness of the fracture surface. Ion milling is time consuming, and artifacts are caused by ion beam faceting. Ball cratering requires only a fraction of an hour and provides significant magnification of the film cross section. There is sufficient contrast, both in optical and electron microscopy, to distinguish between CdS and CuInSe2 layers. Auger line scans and point analyses across crater walls have been used to determine composition depth dependence. Artifacts associated with this technique are electron beam damage of CdS and CuInSe2 during line scan analysis and smearing of CdS for short distances (∼1 μm) along the crater wall during ball cratering.