Bilayer Insulator Tunnel Barriers for Graphene-Based Vertical Hot-electron Transistors

Abstract

Vertical graphene-based device concepts that rely on quantum mechanical tunneling are intensely being discussed in literature for applications in electronics and optoelectronics. In this work, the carrier transport mechanisms in semiconductor-insulator-graphene (SIG) capacitors are investigated with respect to their suitability as the electron emitter in vertical graphene base transistors (GBTs). Several dielectric materials as tunnel barriers are compared, including dielectric double layers. Using bilayer dielectrics, we experimentally demonstrate significant improvements in the electron injection current by promoting Fowler-Nordheim tunneling (FNT) and step tunneling (ST) while suppressing defect mediated carrier transports. High injected tunneling current densities approaching 10${}^3$ A/cm${}^2$ (limited by series resistance), and excellent current-voltage nonlinearity and asymmetry are achieved using a 1 nm-thick high quality dielectric, thulium silicate (TmSiO), as the first insulator layer, and titanium dioxide (TiO${}_2$) as a high electron affinity second layer insulator. We also confirm the feasibility and effectiveness of our approach in a full GBT structure which shows dramatic improvement in the collector on-state current density with respect to the previously reported GBTs. The device design and the fabrication scheme have been selected with future CMOS process compatibility in mind. This work proposes a bilayer tunnel barrier approach as a promising candidate to be used in high performance vertical graphene-based tunneling devices.

References in corpus (9)

• Two-Dimensional Material Nanophotonics
• Field-effect tunneling transistor based on vertical graphene heterostructures
• A Graphene Field-Effect Device
• Operation of Graphene Transistors at GHz Frequencies
• Utilization of a Buffered Dielectric to Achieve High Field-Effect Carrier Mobility in Graphene Transistors
• Vertical Graphene Base Transistor
• Chemical vapor deposited graphene: From synthesis to applications
• A Graphene-based Hot Electron Transistor
• Deposition of thin silicon layers on transferred large area CVD graphene

Cited by in corpus (6)

• Mixed-Dimensional van der Waals Heterostructures
• Nonequilibrium spin injection in monolayer black phosphorus
• Dielectric Properties and Ion Transport in Layered MoS_{2} Grown by Vapor-Phase Sulfurization
• Going Ballistic: Graphene Hot Electron Transistors
• Graphene in 2D/3D Heterostructure Diodes for High Performance Electronics and Optoelectronics
• Two-dimensional Indium Oxide at the Epitaxial Graphene/SiC Interface: Synthesis, Structure, Properties, and Devices