A new photoreflectance signal possibly due to midgap interface states in buried F-doped SnO_2/TiO_2 junctions

摘要

A new optical anomaly has been found in photoreflectance spectra at temperatures above 250 K at spray-pyrolysis-deposited junctions composed of F-doped SnO2 and anatase TiO2 junctions. The energetic position of this anomaly at room temperature is considerably lower than those associated with the bulk optical transitions of TiO2. Its intensity monotonically grows against the temperature rise. These experimental facts suggest that the new anomaly comes from optical transition from the valence band of TiO2 to midgap interface states. (C) 2019 The Japan Society of Applied Physics