Fabrication of asymmetric Ge Schottky tunneling source n-channel field-effect transistor and its characterization of tunneling conduction

An asymmetric Schottky tunneling source field-effect transistor (STS FET) is a prospective device structure to suppress the short channel effect and to reduce the off-state current. An obstacle to implement a STS FET with a high mobility Ge channel was to form a metal/Ge contact with a low electron barrier height (Φ_BN). Recently, we succeeded in the fabrication of a TiN/Ge contact with an extremely low Φ_BN. In this study, a Ge-STS n-channel FET was fabricated, here PtGe/Ge and TiN/Ge contacts were used as the source and the drain. The device showed well-behaved transistor operation. From the current-voltage measurements in the wide temperature range of 160–300 K, the conduction mechanism from the source to the channel is confirmed to be field emission tunneling. This result will be the first step toward achieving a high-performance Ge-STS n-FET.