Band offsets and electronic properties of the Ga2O3/FTO heterojunction via transfer of free-standing Ga2O3 onto FTO/glass*

Abstract

The determination of band offsets is crucial in the optimization of Ga2O3-based devices, since the band alignment types could determine the operations of devices due to the restriction of carrier transport across the heterogeneous interfaces. In this work, the band offsets of the Ga2O3/FTO heterojunction are studied using x-ray photoelectron spectroscopy (XPS) based on Kraut’s method, which suggests a staggered type-II alignment with a conduction band offset (Δ E C) of 1.66 eV and a valence band offset (Δ E V) of –2.41 eV. Furthermore, the electronic properties of the Ga2O3/FTO heterostructure are also measured, both in the dark and under ultraviolet (UV) illuminated conditions (254 nm UV light). Overall, this work can provide meaningful guidance for the design and construction of oxide hetero-structured devices based on wide-bandgap semiconducting Ga2O3.