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

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 ≈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. The electric dipole layer formed by the off‐centric distribution of electron orbitals between metal and graphene can modulate the effective work‐function of metal electrode in MOS junction. This effect of electric dipole layer is indeed found to make the effective work‐function of Aluminum electrode in Al/SiO2/n‐Si junction with a graphene interlayer inserted at Al/SiO2 interface increase significantly by ∼1.04 eV.