Measurement of SiO2/InZnGaO4 heterojunction band offsets by x-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy was used to measure the energy discontinuity in the valence band (ΔEv) of SiO2/InZnGaO4 (IGZO) heterostructures deposited by low temperature plasma enhanced chemical vapor deposition and sputtering at <50 °C, respectively. A value of ΔEv=1.43±0.15 eV was obtained by using the Ga and Zn 2p3 and In 3d3 and 3d5 energy levels as references. Given the experimental bandgap of 3.2 eV for the IGZO, this would indicate a conduction band offset ΔEC of 4.27 eV in this system.