Thermal annealing studies in epitaxial 4H-SiC Schottky barrier diodes over wide temperature range

Thermal annealing effects on electrical characteristics of Ni/4H-SiC and Ti/4H-SiC Schottky barrier diodes (SBDs) are investigated in the temperature range of 400-1100 °C. The thermal evolution of deep level traps in annealed SBDs is also analyzed by thermally stimulated capacitance (TSCAP) spectroscopy. As-deposited Ni/4H-SiC SBDs exhibited non-ideal electrical properties compared to Ti/4H-SiC SBDs. The electrical parameters of the Ni/4H-SiC SBDs are improved upon annealing at 400 °C for 30 min. in Ar ambient. However, deterioration in the SBD characteristics is observed from the temperature of 500 °C, so optimal annealing temperature for our Ni/4H-SiC SBDs is 400 °C. On the other hand, electrical properties of the Ti/4H-SiC SBDs are found to degrade even from the annealing temperature of 400 °C and hence as-deposited Ti/4H-SiC SBDs have the better properties. No considerable changes in the trap concentrations at Ec-0.63 eV and Ec-1.13 eV are identified in the SBDs up to the annealing temperature of 600 °C. The heat treatment on or above 800 °C results in poor rectifying behavior in both the SBDs, therefore the diode rectification is disappeared from 800 °C.