Largely-Tuned Effective Work-Function of Al/Graphene/SiO2/Si Junction with Electric Dipole Layer at Al/Graphene Interface

Abstract

The effective work-function of metal electrode is one of the major factors to determine the threshold voltage of metal/oxide/semiconductor junction. In this work, it is demonstrated experimentally that the effective work-function of the Aluminum (Al) electrode in Al/SiO2/n-Si junction increases significantly by approximate to 1.04 eV with the graphene interlayer inserted at Al/SiO2 interface. The device-physical analysis of solving Poisson equation analytically is provided when the flat-band voltage is applied to the junction, supporting that the large tuning of Al effective work-function may originate from the electric dipole layer formed by the off-centric distribution of electron orbitals between Al and graphene layer. Our work suggests the feasibility of constructing the dual-metal gate CMOS circuitry just by using Al electrodes with area-specific underlying graphene interlayer.