In-situ stress and thermal stability studies of molybdenum bilayer back contacts for photovoltaic applications

Molybdenum bilayers have been used as back contacts for CIGS and CZTS based solar cell for years. Mo bilayer films undergo a heat treatment during the CIGS/CZTS deposition process which in turn changes the stress and morphological properties and affects the adhesion and morphological features of CIGS/CZTS layers. This work reports in-situ studies of Mo stress variation during anneals ranging from 20°C to 500°C and compares its morphological and electrical properties before and after heating to develop a thermally stable Mo bilayer. We have also used a low tensile stress bilayer developed in this way to demonstrate CZTS and CIAGS films with good adhesion properties.