Effect of lanthanum silicate interface layer on the electrical characteristics of 4H-SiC metal-oxide-semiconductor capacitors

The effect of La-silicate interface layer (IL) on the electrical characteristics of 4H-SiC metal-oxide-semiconductor (MOS) capacitors with atomic-layer-deposited SiO2 (ALD-SiO2) gate dielectrics was investigated. In addition to a slight reduction in the interface state density (Dit), the surface potential fluctuation was greatly reduced due to the reduction in the fixed charges (Qfix) with La-silicate IL. Moreover, two orders of magnitude reduction in the oxide trap density in the ALD-SiO2 layer adjacent to the La-silicate IL was confirmed. Physical analysis revealed the reduction in carbon concentration and incorporation of La atoms adjacent to the La-silicate IL.