The improvement of atomic layer deposited SiO2/4H-SiC interfaces via a high temperature forming gas anneal

This letter reports on the improvement of a SiO2 layer formed by atomic layer deposition on 4H-SiC, using a post-deposition anneal in forming gas ambient. Capacitance–voltage measurements revealed good electrical properties, compared to a thermal oxide which was grown in N 2 O, with flatband voltage values averaging at -0.29 V and a low positive mobile ion charge density in the order of 1010 cm−2. XPS analysis revealed the FG annealed sample to have the most Si rich interface comparatively to other PDAs, with a C:Si ratio of 0.72, allowing more Si bonds to be terminated. SIMS analysis identified an increase in hydrogen near the interface of the FG-annealed sample with a peak concentration of 2.12 × 1021 cm−3. It is concluded that the improvement in electrical performance is due to the hydrogen passivating trap states at the SiO2/4H-SiC interface.