Impacts of band alignment change after interface nitridation on the leakage current of SiO₂/4H-SiC (0001) and (11̄00) MOS capacitors

Unexpected fixed charge generation by an additional annealing after interface nitridation processes at the SiO2/4H-SiC (0001) interfaces

“…Such positive fixed charges could induce the negative V FB or V th shift of SiC MOS devices in addition to the interface dipole layer formation as we have discussed for the MOS capacitors only with NO-POA. 26,27,31) In this study, we did not take into account the influences of bulk fixed charges in the thermally grown oxide layer, because we could fit the data by a single linear line for the thickness range of 10-50 nm without any significant deviations. Also, we excluded the change of dipole effects after N 2 -PNA, because we could obtain almost the same intercept of V FB -T ox plots [ q dipole ms j + D j from Eq.…”

“…[23][24][25] Therefore, it is extremely important to understand the origin of negative V FB or V th shift in nitrided SiC devices. We suggested in a previous report that such negative V FB shift is partially originated from band alignment change by the introduction of a high density of nitrogen atoms at the SiO 2 /SiC interface, 26,27) but its impact on V FB shift is limited. On the other hand, the negative V FB shift would be more significant if it is caused by a significant amount of positive fixed charge generation, although the origin of such fixed charges is unclear.…”

Simultaneous electric dipoles and flat-band voltage modulation in 4H-SiC MOS capacitors through HfO2/SiO2 interface engineering

“…Carbon clusters are primarily formed during the high-temperature thermal oxidation process, oxidizing Si atoms on the SiC surface, believed to be the defects at the SiO 2 /SiC interface [22][23][24]. ALD is a suitable and conventional method for the gate oxide of the 4H-SiC MOSFET [4,25,26], providing good film quality, superior uniformity, precise thickness control [27] and reducing carbon clusters. Figure 5 illustrates the D it of the SiC MOS capacitors with and without the additional HfO 2 layer (T HfO2 : 30 nm, T SiO2 : 5 nm).…”