Impact of Interface Defect Passivation on Conduction Band Offset at SiO2/4H-SiC Interface
The change in energy band alignment of thermally grown SiO2/4H-SiC(0001) structures due to an interface defect passivation treatment was investigated by means of synchrotron radiation photoelectron spectroscopy (SR-PES) and electrical characterization. Although both negative fixed charge and interface state density in SiO2/SiC structures were effectively reduced by high-temparature hydrogen gas annealing (FGA), the conduction band offset (ΔEc) at the SiO2/SiC interface was found to be decreased by about 0.1 eV after FGA. In addition, a subsequent vacuum annealing to induce hydrogen desorption from the interface resulted in not only a slight degradation in interface property but also a partial recovery of ΔEc value. These results indicate that the hydrogen passivation of negatively charged defects near the thermally grown SiO2/SiC interface causes the reduction in conduction band offset. Therefore, the tradeoff between interface quality and conduction band offset for thermally grown SiO2/SiC MOS structure needs to be considered for developing SiC MOS devices.
Robert P. Devaty, Michael Dudley, T. Paul Chow and Philip G. Neudeck
T. Hosoi et al., "Impact of Interface Defect Passivation on Conduction Band Offset at SiO2/4H-SiC Interface", Materials Science Forum, Vols. 717-720, pp. 721-724, 2012