Water-Assisted Liftoff of Polycrystalline CdS/CdTe Thin Films Using Heterogeneous Interfacial Engineering

Recent advances in device design and process optimizations have enabled the production of CdTe devices on flexible substrates, but the necessary high-temperature processing (>450 degrees C) to recrystallize grains limits the use of alternative lightweight substrates. Here, a new synthesis method is reported to create a freestanding CdS/CdTe film by combining high-temperature depositions (CdS/CdTe on Si/SiO2) and a simple lift-off process in a water environment at room temperature. Analysis of the results indicate that the delamination is facilitated by the innate lattice mismatch as well as the presence of an unexpected Te-rich layer (approximate to 20 nm), which accumulates on the SiO2 surface. High-resolution electron microscopy and spectroscopy measurements confirm that the CdS/CdTe film is physically liberated from the substrate without leaving any residue, while also preserving their initial structural and compositional properties.