The positive flat-band voltage (V_FB) shifts of 4H-SiC (0001) MOS capacitors with Al₂O₃/SiO₂ dielectric layers were systematically investigated. After nitridation, there was a negative shift of V_FB due to the dipole layer at the SiO₂/4H-SiC interface induced by Si-N bonds. However, with Al₂O₃ layer deposition on thermally grown oxide, an additional dipole layer was formed at the Al₂O₃/SiO₂ interface, which induced positive shift of V_FB. Interface state density was estimated to show that the Al₂O₃ fabrication process had no impact on the quality of SiO₂/4H-SiC interface.

中文翻译：

---

由氧化物-半导体和氧化物-氧化物界面处的界面偶极层形成引起的 4H-SiC MOS 电容器的平带电压漂移

系统地研究了具有 Al ₂ O ₃ /SiO ₂介电层的 4H-SiC (0001) MOS 电容器的正平带电压 (V _FB ) 偏移。氮化后，由于Si-N键诱导SiO ₂ /4H-SiC界面处的偶极层，V _FB发生负移。然而，随着Al ₂ O ₃层沉积在热生长的氧化物上，在Al ₂ O ₃ /SiO ₂界面处形成了额外的偶极层，这导致了V _{FB 的}正位移。估计界面态密度以表明 Al ₂ O₃制备工艺对SiO ₂ /4H-SiC界面的质量没有影响。