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A dependence of the binding energy of the Hf 4f and O 1s photoemission lines on the thickness of the HfO2 film is identified in HfO2/Si heterojunctions and associated with differential charging phenomena. No shifts of Hf 4f and O 1s binding energies are observed in HfO2/Ge heterojunctions, irrespective of the HfO2 film thickness. The time evolution of Hf 4f and Ge 3d signals correlates with a large number of electrically active traps, which are close to the Ge valence bands and determine a negative charge builds-up at the interface, causing the commonly observed p-type surface inversion in n-Ge.
Publication date: 
19 Nov 2012
Biblio References: 
Volume: 101 Issue: 21 Pages: 211606
Applied Physics Letters