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 (ΦBN). Recently, we succeeded in the fabrication of a TiN/Ge contact with an extremely low ΦBN. 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.