Gate stack and Ni(SiGeSn) metal contacts formation on low bandgap strained (Si)Ge(Sn) semiconductors

GeSn is a promising material to make the most of two worlds [1]: (i) its direct bandgap for high Sn contents yields high-mobility and decent optical properties; (ii) as a CMOS compatible material, it benefits from the maturity of group IV semiconductor ultra-large scale integration. However the benefit of high carrier mobility in MOSFETs or direct bandgap in tunnel-FETs can only be used in combination with a high quality, scaled and low defective gate oxide and metallic contacts. In this work, we report on (i) the fabrication and characterization of MOS capacitors on high-Sn-content direct bandgap GeSn alloys and (ii) the formation of metallic contacts with low resistivity. We will also briefly discuss the Schottky barrier tuning by dopant segregation during Ni-stano-germanidation