Reduction of interface-state density in 4H-SiC n-type metal-oxide-semiconductor structures using high-temperature hydrogen annealing

The effects of hydrogen annealing on capacitance-voltage (C-V) characteristics and interface-state density (D-it) of 4H-SiC metal-oxide-semiconductor (MOS) structures have been investigated. The D-it was reduced to as low as 1x10(11) eV(-1) cm(-2) at E-c-E=0.6 eV using hydrogen annealing above 800 degrees C, where E-c-E is the energy level from the conduction-band edge. Secondary ion mass spectroscopy and D-it analysis revealed that D-it decreased with the increase of hydrogen concentration accumulated at the SiO2/4H-SiC interface. The interface states at SiO2/4H-SiC are thought to be originated from the dangling bonds of C atoms as well as Si atoms, because D-it decreases as the hydrogen annealing temperature increases and saturates around 800 degrees C. This high-temperature hydrogen annealing is useful for accumulation-type SiC metal-oxide-semiconductor field-effect transistors, which have n-type MOS structures to reduce the D-it. (C) 2000 American Institute of Physics. [S0003-6951(00)03012-6].