Reduction of interface state density in SiC (0001) MOS structures by low-oxygen-partial-pressure annealing

We report that annealing in low-oxygen-partial-pressure (low-p(O2)) ambient is effective in reducing the interface state density (D-IT) at a SiC (0001)/SiO2 interface near the conduction band edge (E-C) of SiC. The D-IT value at E-c - 0.2 eV estimated by a high (1 MHz)-low method is 6.2 x 10(12) eV(-1)cm(-2) in as-oxidized sample, which is reduced to 2.4 x 10(12) eV(-1)cm(-2 )by subsequent annealing in O-2 (0.001%) at 1500 degrees C, without interface nitridation. Although annealing in pure Ar induces leakage current in the oxide, low-p(O2) annealing does not degrade the oxide dielectric property (breakdown field similar to 10.4 MV cm(-1)). (C) 2019 The Japan Society of Applied Physics