Vector Substrates: How to Grow Epitaxially Impossible Heterostructures

Substrates play a crucial role in thin film deposition, but they do not always align with the specific requirements of a particular experiment or application. For instance, they might be expensive or unavailable with a desired crystal lattice structure. To address this, we introduce the novel concept of "vector substrates." In this approach, the template layer for growing thin films is both chemically and structurally independent from the main substrate. Vector substrates are fabricated by transferring a membrane, which serves as the template layer and is grown on a reusable parent substrate, onto a carrier substrate. The template and carrier layers can be independently chosen and optimized, which reduces material costs and offers more flexibility. We validate the feasibility of this technology by presenting sets of vector substrates for high-quality epitaxial film growth and by demonstrating a clean interface between the transferred membrane and the carrier substrate. The vector substrate concept is in its early stages of development but holds significant promise to supplement conventional substrates and drives future advancements in substrate technology and the deposition of films and heterostructures.