III-V epitaxy is normally performed on mono-crystalline substrates a few hundred micrometers thick, while the active thin-film device itself is usually only a few micrometers. During the fabrication process, the substrate is either etched or retained in the structure without serving any functional purpose. In this project, we aim to detach the thin film from the substrate. This will yield semiconducting membranes that are altogether flexible, lightweight, integrable, and high-performance (both optically and electronically). These membranes have applications in numerous fields, including silicon photonics, flexible devices, and high-efficiency solar cells. Furthermore, this approach offers the opportunity to recycle the mono-crystalline substrates, which are both expensive and made from critical materials, thereby reducing material consumption 100-fold. Our strategy is to deposit a graphene layer onto the substrate before performing the epitaxy (see figure in attached pdf). We have demonstrated that graphene enables the fabrication of high-quality mono-crystalline material while allowing its exfoliation. The general purpose of the internship is to develop this method, which requires both exploring the fundamental physical phenomena occurring at the graphene surface during material synthesis and defining practical methodologies and quality assessment protocols for each process step. Without restrictions, we aim to fabricate ultrathin solar cells.