| Summary: | By means of plane wave pseudopotential method we have studied the electronic properties of the heterostructure formed by an high dielectric constant (<em>k</em>) oxide, the hexagonal La<sub>2</sub>O<sub>3</sub> epitaxially grown with (0001)-orientation on Si (111) substrate. We found that for La<sub>2</sub>O<sub>3</sub> both the dielectric constant along the growth direction and the band gap are larger in the epitaxial film than in the bulk. By super-cell techniques we have computed the band alignment of the junction finding a valence band offset and a conduction band offset of ~1.6 eV and ~1.7 eV respectively. We demonstrate that the band alignment can be engineered by <em>δ</em>-doping the interface: our simulations show that, by doping the interface with S or Se monolayer, the valence (conduction) band offset increases (decreases) of about 0.5 eV without the formation of spurious electronic states in the semiconductor band-gap. The simulation of the critical thickness of pseudomorphic Lanthana film complete the work. Our results are relevant for the realization of a new generation of devices based on ultra-scaled complementary metal oxides semiconductors (CMOS) technology.
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