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2D transition metal dichalcogenide based van der Waals materials are promising candidates to realize tunnel field effect transistors (TFETs) with a steep subthreshold swing (SS) for low‐power applications. Their atomically flat, self‐passivated layers offer potentially defect free interlayer tunneling. There are still several issues that need to be addressed to experimentally achieve a steep SS, e.g., the Schottky contacts, impact of thick layers, and device architecture with respect to gate configuration. This paper resolves these challenges by experimentally demonstrating MoS2/MoTe2 TFETs and their electrical characteristics, in conjunction with ab initio simulations and surface Kelvin probe microscopy. The Schottky barrier's effect at the contact regions are isolated by fabricating individual buried gates below the contacts. Devices with different top and bottom gate configurations are produced to understand the impact of gate placement on the heterostructure characteristics. Quantum transport simulations are performed on MoS2/MoTe2 multilayer stack to evaluate the impact of multiple layers on TFET performance, effect of gate placement, and the mechanism behind indirect tunneling over the heterojunction region. This work highlights the influence of the Schottky contacts, multiple layers and the role of different gate configurations on the band‐to‐band tunneling phenomenon in 2D heterojunction TFETs. [ABSTRACT FROM AUTHOR]

Two-dimensional transition metal dichalcogenide (TMD) semiconductors have risen as an important material class for novel nanoelectronic applications. Molybdenum disulfide (MoS2) is the most representative TMD compound due to its superior stability and attractive properties for (opto-) electronic devices. However, the synthesis of single-crystalline and functional MoS2 across large-area substrates remains crucial for its successful integration in semiconductor industry platforms. Therefore, this work focuses on the study of MoS2 epitaxy via two well-established industry-compatible synthesis methods, promising for the large-area and single-crystalline integration of van der Waals (vdW) materials. These methods are molecular beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOVPE) and have studied MoS2 quasi-vdW heteroepitaxy on reconstructed sapphire substrates and MoS2 vdW homoepitaxy on exfoliated MoS2 flakes. By examining the MoS2 structural properties using diffraction and spectroscopy techniques, the epitaxial relation and crystal quality are assessed, which reveals insights into the prevalence of inter- and intragrain defects such as grain boundaries and sulfur vacancies. The MBE method yields superior epitaxial MoS2 registry on both sapphire and MoS2 surfaces as compared to MOVPE, although inferior defectivity arises from the typical lower MBE growth temperature and chalcogen partial pressure. Moreover, both synthesis methods generate high densities of twinned MoS2 grain boundaries, which hamper defect-free integration. As a result, this challenging integration might become an important bottleneck for industrial TMD-based applications with a low tolerance for material defects. [ABSTRACT FROM AUTHOR]