Band offsets in HfTiO/InGaZnO4 heterojunction determined by X-ray photoelectron spectroscopy

• Band offsets in HfTiO/InGaZnO4 heterojunction were determined by XPS.
• Valence band offset of HfTiO/IGZO heterojunction is determined to be 0.35 eV.
• Conduction band offset of 1.61 eV is deduced for HfTiO/IGZO heterojunction.

In current report, X-ray photoelectron spectroscopy has been pursued to obtain the valence band discontinuity (ΔEv) of sputter deposited HfTiO/InZnGaO4 (IGZO) heterostructures. A ΔEv value of 0.32 ± 0.1 eV was obtained by using the Ga 2p3/2, Zn 2p3/2, and In 3d5/2 energy levels as references. Taking into consideration the experimental band gaps of 5.35 eV and 3.39 eV for HfTiO and IGZO thin films measured by absorption method, respectively, this would result in a conduction band offset of 1.64 eV in this heterostructure.