For SiO2/4H–SiC (0001) and (000–1) n-type metal-oxide-semiconductor capacitors, the relationship between flatband voltage and the thickness of oxide was investigated after NO post-oxidation annealing to evaluate the expected flatband voltage (VFB) without a fixed charge effect. After removal of the fixed charge effect, there was an anomalous negative shift of VFB on (0001) 4H–SiC, which would be attributed to the result of dipole layer formation at the interface. The effects of the dipoles were investigated from the perspective of the SiO2/4H–SiC band alignment shift. We could find the correlation between the shift of VFB and that of the band alignment between SiO2 and the 4H–SiC interface; we concluded that stable Si–N bonds at the interface induce a dipole layer, and this is one of the reasons for the unexpected shift reported for VFB or threshold voltage of metal-oxide-semiconductor field-effect transistors, as well as the fixed charge effects. A significant difference in the band alignment on (0001) and (000–1) was also clarified, which would be one of the reasons for the disagreement of VFB on those faces.

中文翻译：

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NO-POA引起的SiO2/4H-SiC（0001）和（000-1）MOS电容器的异常能带排列变化及其可能的起源

对于 SiO2/4H-SiC (0001) 和 (000-1) n 型金属氧化物半导体电容器，在 NO 后氧化退火后研究了平带电压与氧化物厚度之间的关系，以评估预期的平带电压（ VFB) 没有固定电荷效应。去除固定电荷效应后，(0001) 4H-SiC 上的 VFB 出现异常负移，这归因于界面处偶极层形成的结果。从 SiO2/4H-SiC 能带排列偏移的角度研究偶极子的影响。我们可以发现 VFB 的位移与 SiO2 和 4H-SiC 界面之间的能带排列之间的相关性；我们得出结论，界面处稳定的 Si-N 键会产生偶极层，这是金属氧化物半导体场效应晶体管的 VFB 或阈值电压出现意外偏移的原因之一，以及固定电荷效应。还澄清了（0001）和（000-1）上波段对齐的显着差异，这将是这些面上 VFB 不一致的原因之一。