Vector Substrates: Idea, Design, and Realization

• Published in: Advanced functional materials 2024-01, Vol.34 (4), p.n/a
• Main Authors: Harbola, Varun, Wu, Yu‐Jung, Hensling, Felix V. E., Wang, Hongguang, Aken, Peter A., Mannhart, Jochen
• Format: Article
• Language: English
• Subjects: Crystal growth; Crystal lattices; Crystallography; Deposition; epitaxy; Film growth; membranes; oxides; Substrates; Thin films
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202306289

Substrates are essential in thin‐film deposition, yet they do not always meet the requirements of a given application. For example, they might be prohibitively expensive or not even available with the necessary crystal lattice structures. This paper introduces the innovative concept of “vector substrates,” where the template layer for thin‐film growth, referred to as vector, is chemically and crystallographically independent of the bulk of the substrate. This approach reduces material costs and offers unparalleled flexibility. The fabrication of vector substrates leverages thin‐film membrane technology. The process begins by growing a template layer on a parent substrate. The template layer is then transferred onto a carrier substrate, thereby generating the vector substrate. Vector substrate technology enables researchers and manufacturers with thin‐film deposition facilities to fabricate optimized substrates that would otherwise be difficult to obtain using bulk single‐crystal growth technology. An in‐depth discussion of the benefits and limitations of vector substrates compared with traditional substrates is provided. Furthermore, the practical viability of the concept is demonstrated by fabricating sets of vector substrates. Although this concept is still in its infancy, it has a significant potential to complement conventional substrates for future advancements in substrate technology and thin‐film deposition. This work introduces vector‐substrates for thin film deposition, promising to reduce costs and provide a high level of flexibility by separating the template layer for epitaxial growth from the bulk of the substrate. This method utilizes freestanding membranes and stands to complement traditional substrates while also demonstrating potential for new kinds of interfaces and heterostructures.