Lagging Thermal Annealing for Barrier Height Uniformity Evolution of Ni/4H-SiC Schottky Contacts

The electrical behavior improvement of nonuniform Ni/4H-SiC Schottky diodes, akin to that caused by thermal annealing, is demonstrated after continuous exposure to high operating temperatures (400 <tex-math notation="LaTeX">∘</tex-math> C). After only the standard rapid thermal annealing (RTA), samples with different contact diameters exhibit barrier height and ideality factor fluctuations, typical for nonuniform contacts. After 2 h at 400 <tex-math notation="LaTeX">∘</tex-math> C, a shift in Schottky barrier is observed, toward a plateau of 1.63 V, constant with temperature and bias, for all investigated structures, with current flow being nearly fully accounted for by single-barrier thermionic emission. Coupled with operational contact area enhancement, this lagging treatment ensures the devices' ability to operate at high temperatures.