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

The electrical behavior improvement of nonun iform Ni/4H-SiC Schottky diodes, akin to that caused by thermal annealing, is demonstrated after continuous exposure to high operating temperatures (400(degrees)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(degrees)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.