Ar Plasma Treatment for III-V Semiconductor-Based Transistor Source/Drain Contact Resistance Reduction

Abstract

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 similar to 60x reduction of the specific contact resistivity (rho(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 rho(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).