Band alignment between (1Â 0Â 0)Si and Hf-based complex metal oxides

The electron energy band alignment at the interfaces of Hf-based complex oxides with (100)Si and Au is determined using internal photoemission and photoconductivity measurements. In Hf:Al and Hf:Ti oxides the cations form two sub-networks with no detectable interaction of their unoccupied electron states in the oxide conduction band. Only in the case of Hf and Ta cations with the same symmetry and principal quantum number of the unoccupied atomic orbitals, a gradual variation of the conduction band bottom energy is observed suggesting quantum mixing of Hf- and Ta- 5d* states.