Characterization of Al2O3/LaAlO3/SiO2 Gate Stack on 4H-SiC After Post-Deposition Annealing

We fabricated Al ₂ O ₃ /LaAlO ₃ /SiO ₂ (ALS) gate stacks on 4H-SiC, with LaAlO ₃ (LAO) film being annealed in O ₂ atmosphere. The ALS gate stack annealed at 700 °C exhibits a much higher breakdown effective electric field ( ${E}_{\text {eff}}$ ), which is approximately 1.8 times higher than that of traditional SiO ₂ gate oxide. The ALS gate stack also yields a low interface state density ( ${D}_{\text {it}}$ ) thanks to the intact LAO film. However, an annealing temperature as high as 800 °C induced traps in the LAO film and deteriorated the SiO ₂ –SiC interface. The 700 °C-annealed LAO film with a high dielectric constant ( $\kappa $ ) of 14 and a low trap density, coupled with good electrical characteristics, makes it a promising gate dielectric for SiC power metal-oxide-semiconductor (MOS) device applications.