Fermi level depinning in metal/Ge Schottky junction for metal source/drain Ge metal-oxide-semiconductor field-effect-transistor application

Abstract

Schottky barrier height modulation in metal/Ge Schottky junction was demonstrated by inserting an ultrathin interfacial silicon nitride layer. The SiN interfacial layer suppressed strong Fermi level pinning in metal/Ge Schottky junction, which resulted in effective control of Schottky barrier height. Metal/SiN/Ge Schottky diode was systematically investigated in terms of SiN thickness dependence and metal work function dependence. At an optimal SiN thickness, Ohmic contact between metal and Ge was obtained as a result of Fermi level depinning, and almost ideal Schottky barrier height determined by the work function difference between the metal and Ge was achieved. This technology was finally applied to metal source/drain Ge metal-oxide-semiconductor field-effect-transistors with low source/drain resistance.