Band alignment in ZrSiO4/ZnO heterojunctions

We have measured the band offsets of sputtered ZrSiO4 on bulk ZnO wafers using X-Ray Photoelectron Spectroscopy and obtained the bandgaps of these two materials using reflection electron energy loss spectroscopy. The valence band offset was determined to be −0.60 eV ± 0.04 eV for ZrSiO4 on ZnO, while the respective bandgaps were 3.22 eV for ZnO and 5.9 eV for ZrSiO4. The conduction band offset for ZrSiO4/ZnO was then determined to be 3.28 eV. The ZrSiO4/ZnO system has a staggered, type II alignment. This means that while ZrSiO4 may be useful for surface passivation applications on ZnO, it is not suitable for thin film transistors where a positive valence band offset is needed.