Schottky source/drain Ge metal-oxide-semiconductor field-effect transistors with directly contacted TiN/Ge and HfGe/Ge structures

Metal/Ge contacts with high Schottky barrier heights on p- and n-Ge substrates could be formed using direct sputter depositions from TiN and Hf, respectively. The barrier heights were 0.53 and 0.60 eV for the p- and n-Ge substrates, respectively, which are available to source/drains (S/Ds) in Schottky n- and p-channel metal-oxide-semiconductor field-effect transistors (MOSFETs). We fabricated the n- and p-MOSFETs and demonstrated their operation. In particular, the n-MOSFET operation is the first demonstration of S/D using directly contacted metal/Ge. This work opens a method for embodying Schottky S/D Ge complementary MOS devices.