[5a-A203-1~10] 15.6 Group IV Compound Semiconductors (SiC)

▲ [5a-A203-5] Verification of density distribution of near-interface traps in 4H-SiC MOS capacitors with different oxide thicknesses

〇(D)Xufang Zhang¹, Dai Okamoto¹, Tetsuo Hatakeyama², Mitsuru Sometani², Shinsuke Harada², Noriyuki Iwamuro¹, Hiroshi Yano¹ (1.Tsukuba Univ., 2.AIST)

Keywords:4H-SiC MOS capacitors, Near-interface traps, density distribution

Near-interface traps (NITs) are one of the most harmful oxide defects locating near the interface of SiO₂/4H-SiC, which leads to the poor properties of 4H-SiC MOSFETs. Recently, we have developed a modified distributed circuit model to characterize the NITs. In the proposed model, we assumed an exponentially decaying distribution of NITs for 4H-SiC MOS capacitors with oxide thickness of around 50 nm to explain both the C–f and G–f characteristics in strong accumulation conditions. However, the exponential distribution assumption has not been fully validated. To assess the validity of the exponential assumption of NITs, it would be effective to test the distributed circuit model for different oxide thicknesses formed by different oxidation times. On the other hand, Watanabe et al. reported that the D_it depends on oxidation time, and the D_it increases with increasing the oxide thickness. Here, we verified the exponential approximation of NIT distribution by using the MOS capacitors formed by different oxidation times and also investigated the impact of oxidation time on the NIT density distribution in 4H-SiC MOS capacitors with the proposed model.