Release Time:2019-03-12  Hits:

Indexed by: Journal Article

Date of Publication: 2018-04-01

Journal: CHINESE PHYSICS B

Included Journals: SCIE

Volume: 27

Issue: 4

ISSN: 1674-1056

Key Words: 4H-SiC; interface defect; density of states; first principle

Abstract: An amorphous SiO2/4H-SiC (0001) interface model with carbon dimer defects is established based on density functional theory of the first-principle plane wave pseudopotential method. The structures of carbon dimer defects after passivation by H-2 and NO molecules are established, and the interface states before and after passivation are calculated by the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional scheme. Calculation results indicate that H-2 can be adsorbed on the O-2-C = C-O-2 defect and the carbon-carbon double bond is converted into a single bond. However, H-2 cannot be adsorbed on the O-2-(C = C)'-O-2 defect. The NO molecules can be bonded by N and C atoms to transform the carbon-carbon double bonds, thereby passivating the two defects. This study shows that the mechanism for the passivation of SiO2/4H-SiC (0001) interface carbon dimer defects is to convert the carbon-carbon double bonds into carbon dimers. Moreover, some intermediate structures that can be introduced into the interface state in the band gap should be avoided.