that O atoms mainly contribute to the VBM of λ-Ta 2 O 5 , and thus the amount of
interface O atoms has a great impact on the VBM of metal oxides. As a consequence,
the valance band offset (VBO) increases with the reduction of the amount of
interface O atoms, and the VBO can increase up to 1.5 eV by gradually reducing
the interface O atoms from 0 to 50%. This increase is attributed to the downward
shift of the VBM of Ta 2 O 5 due to the reduced electronegativity of the total interfacial
oxygen as compared to that of the c-O12. Thus, the initial SBH of the Cu/Ta 2 O 5 /Pt
atomic switch can be experimentally controlled by tuning the interface O concentration, a property directly related to the ambient oxygen pressure.
In summary of this subsection, we have discussed the interface structures of Cu/aTa 2 O 5 /Pt atomic switch. Our results reveal that the Cu atoms tend to be ionized at the
Fig. 10 Density of states of a-O12 model. Adapted from Ref. [8] with permission from American
Chemical Society
108
S. Watanabe and B. Xiao
interface O atoms has a great impact on the VBM of metal oxides. As a consequence,
the valance band offset (VBO) increases with the reduction of the amount of
interface O atoms, and the VBO can increase up to 1.5 eV by gradually reducing
the interface O atoms from 0 to 50%. This increase is attributed to the downward
shift of the VBM of Ta 2 O 5 due to the reduced electronegativity of the total interfacial
oxygen as compared to that of the c-O12. Thus, the initial SBH of the Cu/Ta 2 O 5 /Pt
atomic switch can be experimentally controlled by tuning the interface O concentration, a property directly related to the ambient oxygen pressure.
In summary of this subsection, we have discussed the interface structures of Cu/aTa 2 O 5 /Pt atomic switch. Our results reveal that the Cu atoms tend to be ionized at the
Fig. 10 Density of states of a-O12 model. Adapted from Ref. [8] with permission from American
Chemical Society
108
S. Watanabe and B. Xiao