Deformation and material removal in a nanoscale multi-layer thin film solar panel using nanoscratch

Amorphous Si thin film solar panels are multi-layer structures consisting of nanometric layers of hard and brittle materials. The deformation and material removal characteristics of the panel cross-section were investigated using nano-mechanical testing. Nanoindentation and nanoscratching were performed using indenters of various geometries at a range of loads. Atomic force microscopy and electron microscopy were used to study the resulting deformation structures and mechanisms. Plastic deformation of the brittle layers was observed below a critical scratch depth, where material removal occurred without fracture. The critical depth was found to be dependent on indenter geometry and material properties. The indenter tip with the smallest included angle resulted in the greatest scratch depths and material removal. The increased scratching speed also improved the removal efficiency. The results of this work can be applied to develop the ductile regime machining process for thin film solar panels.