Si/Ge1−xSnx/Si transistors with highly transparent Al contacts

We study the monolithic quasi-ohmic contact formation with single-elementary Al to Ge${}_{1-x}$Sn${}_x$ channel devices with various Sn concentrations between 0.5 % and 4 %. Thereby we investigate the influence of increasing Sn content on the electrical transport properties in field-effect transistors for a wide temperature range between 77 K and 400 K. At low temperatures, the devices exhibit improved performance metrics, promising for cryo-CMOS applications. Compared to pure Ge control devices, the introduction of Sn into the channel leads to a 20 times increased on-current. In a multi-gate architecture, we analyze the decoupled influence of the carrier injection through the metal–semiconductor junction and the channel conduction.