Experimental estimation of charge neutrality level of SiO₂

Highlights: • The charge neutrality level (CNL) of SiO₂ is experimentally obtained to be 4 eV above the VBM of SiO₂. • This paper proposes a new method to experimentally obtain the CNL of oxide. • Our work confirm the feasibility of gap state model in understanding the band lineup at oxide/semiconductor structure. - Abstract: The charge neutrality level of SiO₂ is experimentally extracted by investigating conduction band offset (CBO) of SiO₂/Si stack with different SiO₂ thicknesses using X-ray photoelectron spectroscopy. The CBO is found to be dependent on SiO₂ thickness. The CNL of SiO₂ is determined to be 4 eV above valence band maximum by modeling the CBO vs. thickness of SiO₂ using gap states and charge neutrality level based model.