Electrical Characteristics of SiO2 Deposited by Atomic Layer Deposition on 4H-SiC After Nitrous Oxide Anneal

Properties of SiO2 gate dielectric deposited by atomic layer deposition (ALD) on Si-face of 4H silicon carbide (SiC) were systematically studied. The interface state and effective fixed charge densities of ALD SiO2 on n-type 4H-SiC with various post deposition anneal (PDA) conditions were evaluated. It has been found that nitrous oxide (N2O) PDA not only reduces the effective fixed charge density, which includes the fixed oxide charge and charged interface states, at SiC/SiO2 interface but also decreases the gate leakage current. Negative effective fixed charge is observed at SiC/ALD SiO2 interface after N2O PDA. ALD SiO2-based lateral n-channel MOSFETs show high threshold voltage with the promising field-effect mobility and the peak field-effect mobility increases with N2O PDA temperature.