Ar plasma treatment for III-V semiconductor-based transistor source/drain contact resistance reduction

In this study, a lower contact resistant metal/n-GaAs contact is formed through Ar plasma treatment of the GaAs surface. A native oxide of GaAs substrate is effectively removed by Ar ion bombardment. At the metal-semiconductor (MS) contact interface, the Fermi-level pinning induced by the Ga- and As-oxide bonds results in a large Schottky barrier height. However, removing the native oxide through Ar ion bombardment causes the Fermi-level to become unpinned. leading to ∼60x reduction of the specific contact resistivity (ρ_c). Although the Ar ion bombardment can damage the surface of GaAs, only native oxide is removed with smooth surface because the plasma is created under low power. A simulation based MS contact model is implemented to confirm the ρ_c values for high substrate doping concentration. The results suggest that the proposed Ar treatment method can be used for the non-alloyed source/drain (S/D) contact resistance reduction of metal-oxide-semiconductor field effect transistors (MOSFETs) and high electron mobility transistors (HEMTs).