Perspectives for the Growth of Epitaxial 2D van der Waals Layers with an Emphasis on Ferromagnetic Metals for Spintronics

Abstract

Wafer scale epitaxial growth of 2D van der Waals materials and heterostructures is of ultimate importance for applications. Using synthetic thin film methods is also important to realize 2D materials which do not exist in nature and cannot be grown in equilibrium in bulk form. In this work, the perspectives in wafer scale growth of 2D van der Waals metallic ferromagnets (FMs) and the combination with other structurally and chemically compatible materials are described to propose functional devices. The areas such as 2D van der Waals ferromagnetic π‐junctions for quantum computing, and all 2D magnetic tunnel junctions (MTJs) and spin orbit torque devices which can be used for spintronics are identified. It is foreseen that a new class of Janus materials which can be realized only by epitaxial synthetic methods can enhance the performance of spintronic devices. Finally, this work describes the perspectives to overcome the shortcomings of epitaxial techniques and layer transfer by proposing remote epitaxy for the detachment of 2D materials films from the substrate and the use of liquid substrates or liquid catalysts to achieve single crystalline 2D materials films over large areas on the wafer.

van der Waals 2D transition metal dichalcogenide/organic hybridized heterostructures: recent breakthroughs and emerging prospects of the device

“…An alternative approach, metal–organic chemical vapor deposition (MOCVD), has demonstrated successful results in the fabrication of polycrystalline MoS 2 on 4-inch SiO 2 /Si substrates and the creation of FETs with an impressive 99% yield and satisfactory mobility around 30 V s cm −2 , as reported. 46 MOCVD offers a range of precursors with varying decomposition temperatures, allowing for the precise control of growth conditions including temperature and growth rate. Crucially, these precursors must prevent gas-phase reactions to maintain the crystalline quality and composition control.…”

“…56 It uses physical vapor deposition (PVD), and refractory metals such as Mo, W, Cr, Fe, and Co are vaporized. 46,57 However, magnetic metals can cause scattered evaporation beams. An alternative is using high-temperature (above 850 °C) effusion cells, but it increases thermal load and contamination risks.…”