Interfacial study and energy-band alignment of annealed Al2O_3 films prepared by atomic layer deposition on 4H-SiC

摘要

Al2O_3 films were prepared by atomic layer deposition using trimethylaluminum and H_2O at 250 ℃ on 4H-SiC substrates and annealed at 1000 ℃ in N_2. The as-deposited and annealed Al2O_3 films were measured and analyzed near the Al2O_3/SiC interfaces by using an X-ray photoelectron spectroscopy (XPS) with etching processing. The XPS results showed that as-deposited Al2O_3 films were O-rich and converted to anhydride Al2O_3 films after annealed at 1000 ℃ in N_2. Si suboxides were found both at as-deposited and annealed Al2O_3/SiC interfaces. Energy band shift between Al2O_3 and 4H-SiC was found after annealing. The conduction band offsets of as-grown and annealed Al2O_3/SiC were 1.90 and 1.53 eV, respectively. These results demonstrated that Al2O_3 can be a good candidate to be applied in SiC metal-oxide-semiconductor devices.