Via Size-Dependent Properties of TiAl Ohmic Contacts on 4H-SiC

P-type Ti/Al-based contact vias of different sizes but identical processing were electrically characterized using linear transfer length method (TLM) patterns and metal-oxide-semiconductor (MOS) transistors. While the TLM patterns and MOS transistors with large vias follow ohmic contact behavior, Schottky contact properties were observed for smaller contact via dimensions. Focused ion beam (FIB) analysis of the contact vias verified the presence of Ti3SiC2 on large 66 µm x 25 µm contact vias and its absence on smaller 16 µm x 3 µm ones, correlating its absence with the electrical Schottky properties.