Energy band alignment of atomic layer deposited H_fO_2 on epitaxial (110)Ge grown by molecular beam epitaxy

摘要

The band alignment properties of atomic layer HfO_2 film deposited on epitaxial (110)Ge, grown by molecular beam epitaxy, was investigated using x-ray photoelectron spectroscopy. The cross-sectional transmission electron microscopy exhibited a sharp interface between the (110)Ge epilayer and the HfO_2 film. The measured valence band offset value of HfO2 relative to (110)Ge was 2.28 ± 0.05 eV. The extracted conduction band offset value was 2.66 ± 0.1 eV using the bandgaps of HfO_2 of 5.61 eV and Ge bandgap of 0.67 eV. These band offset parameters and the interface chemical properties of HfO_2/(110)Ge system are of tremendous importance for the design of future high hole mobility and low-power Ge-based metal-oxide transistor devices.