Enhanced Raman Scattering in Copper-doped TiO2 films

• Pure TiO2 and Cu-doped TiO2 films on LaAlO3 substrates by molecular beam epitaxy
• Interface states of Cu–TiO2 samples enriched compared to TiO2 samples
• Charge transfer enhanced the vibrational patterns A1g mode in Raman scattering of LaAlO3.

Pure TiO2 and copper-doped TiO2 (Cu–TiO2) films were prepared on LaAlO3(111) substrates by molecular beam epitaxy. We found that the Cu–TiO2 films could enhance the Raman scattering of LaAlO3. The Raman scattering of the LaAlO3 substrates is selectively enhanced in the Cu-doped TiO2/LaAlO3 heterojunctions. The doped Cu on TiO2 can enrich the energy level states of TiO2, which is attributed to the dominant contribution of the TiO2-to-LaAlO3 charge transfer (CT) mechanism. This work is valuable in developing doped TiO2 films which are promising materials used in the field of surface-enhanced Raman scattering as well as in studying the CT mechanism between Cu and TiO2 for potential photoelectrochemical applications.