Process-dependent band structure changes of transition-metal (Ti,Zr,Hf) oxides on Si (100)

Fulton, C. C.; Lucovsky, G.; Nemanich, R. J.
January 2004
Applied Physics Letters;1/26/2004, Vol. 84 Issue 4, p580
Academic Journal
In this study, we have deposited Ti, Zr, and Hf oxides on ultrathin (∼0.5 nm) SiO[sub 2] buffer layers and have identified metastable states which give rise to large changes in their band alignments with respect to the Si substrate. This results in a potential across the interfacial SiO[sub 2] layer, significant band bending, and large shifts of the high-k valence band. The magnitude of the shift differs for the three materials and is dependant on both the SiO[sub 2] buffer layer thickness and annealing temperature. We propose a model where excess oxygen accumulates near the high-k-SiO[sub 2] interface providing electronic states, which are available to electrons that tunnel from the substrate. © 2004 American Institute of Physics.


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