Band alignment of Ta2O5 on sulphur passivated Germanium by X-ray photoelectron spectroscopy

In this work Ta
₂
O
₅
films were deposited on germanium, by atomic layer deposition (ALD) at 250°C with and without sulphur passivation. X-ray photoelectron spectroscopy (XPS) was carried out to investigate the band line-up of Ta
₂
O
₅
films with respect to germanium. The results show that the valance band offsets of Ta
₂
O
₅
with respect to sulphur-passivated and unpassivated Germanium are 2.67 eV and 2.84 respectively. The band gap value of 20 nm thick Ta
₂
O
₅
films was determined to be 4.44 eV from the electron energy loss spectrum of O1s core level.