MoS2/MoTe2 Heterostructure Tunnel FETs Using Gated Schottky Contacts. (4th November 2019) - Balaji, Yashwanth
Abstract: 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 : Heterojunction tunnel field effect transistors (TFETs) based on MoS2 /MoTe2 are fabricated by placing individual gates below the contact regions to suppress the Schottky barrier's influence on band‐to‐band tunneling current. The work reports a detailed study on the influence of source/drain contacts, gate architecture, and impact of multiple layers in conjunction with quantum transport simulations on 2D TFET performance.