Band offsets, charge transfers, and formation energies of oxygen vacancies in c-ZrO2/Si interface

Abstract Due to the high dielectric constant and wide band gap, ZrO 2 has become a widely used gate dielectric material in complementary metal-oxide-semiconductor devices, and the ZrO 2 /Si interface plays a critical role in determining overall device performance. In this work, we systematically study the effects of oxygen vacancy defects on the band structure, band offset, and charge transfer in cubic ZrO 2 /Si (c-ZrO 2 /Si) interface structure. Our results reveal that the constructed (c-ZrO 2 ) 9 /(Si) 9 interface is an indirect band gap semiconductor, with the band edges contributed by Si and a band offset greater than 2 eV. The three oxygen vacancy defects reduce the band gap and induces quasi-flat band. The band offset is partially influenced by the location of oxygen vacancies, but the valence band offset and conduction band offset always exceed 1 eV. Notably, the V O 1 and V O 2 alter the bonding environment and charge transfer of adjacent Si atoms, whereas V O 3 , located farther from the interface, preserves the native charge transfer characteristics of the (c-ZrO 2 ) 9 /(Si) 9 interface. The V O 1 0 defect exhibits the lowest formation energy across all conditions, with the value in O-poor conditions being 6.992 eV lower than that in the O-rich environment. These findings suggest that the presence of oxygen vacancies may significantly affect the electrical and carrier properties of c-ZrO 2 /Si interface, providing theoretical insights into optimizing the design and fabrication of Si-based semiconductor devices.