Valence band offsets of the strained and longitudinally relaxed diamond/c-BN superlatticesTANG Min-yan ( ), XU Run ( ), GAO Yong-chao ( ), WANG Lin-jun ( ) Abstract The valence band offsets of the strained and longitudinally relaxed diamond/cubic boron-nitride (c-BN) (110) superlattice are investigated by the plane wave density functional theory approach and using the on-site core electron as a reference energy level. For the strained diamond/c-BN superlattice, the valence band offset of around 1.50 eV is in good agreement with those using all the electrons methods. As for the longitudinally relaxed superlattice, the valence band offset of around 1.28 eV is smaller than that of the strained superlattice. The reason for this is mainly due to the split of the valence band maximum caused by the anisotropic strain.

The band offset and interface chemistry of HfO 2 films prepared by ultrahigh-vacuum electron-beam evaporation was investigated by synchrotron radiation photon electron spectroscopy (SRPES). A relatively large valence band (VB) offset of the HfO 2 film with Si was determined to be 3.56 eV. Both the Hfsilicate and a small number of Hf-Si bonds were formed at the interface of HfO 2 /Si. This Hf-Si bond, which cannot be prevented completely in an ultrahigh-vacuum preparation system using the Hf metallic source despite the atomic oxygen source adopted, may be mainly responsible for this large value of VB offset of HfO 2 /Si(001). This result also suggests that metal-silicon bonds at the interface of high k oxides on Si may generally lead to a larger VB offset than that with all silicon atoms at the interface bonding directly with oxygen.

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