Shallow electron traps at the 4H-SiC/SiO2 interface

Low-temperature electrical measurements and photon-stimulated electron tunn eling experiments reveal the presence of a high density of interface states at around 0.1 eV below the conduction band of 4H-SiC at its interface with thermally grown SiO2. These states, related to defects in the near-interfa cial oxide layer, trap a considerable density of electrons from the SiC, an d are likely responsible for the severe degradation of the electron mobilit y observed in the surface channel of 4H-SiC/SiO2 devices. The negative impa ct of the observed defects can be minimized by using SiC modifications (e.g ., 6H, 15R, 3C) with a larger conduction band offset with the oxide than 4H -SiC leading to a largely reduced density of electrons trapped in the oxide . (C) 2000 American Institute of Physics. [S0003-6951(00)01503-5].