Metal-ion doped p-type TiO2 thin films and their applications for heterojunction devices

Our study revealed that wet chemically processed metal-ion (i.e., Al+3, Cr+3, Ni+2) doped TiO2 thin films could convert its conducting nature from n-type to extrinsic p-type. X-ray photoelectron spectroscopy (XPS) showed shifting of valence band edges with increasing doping concentration. The metal-ion doped TiO2 films were employed as active component in bipolar heterojunction devices, which recorded low turn-on voltage and showed rectification behavior. These results were analyzed to conclude that the doped TiO2 is p-type in nature. Temperature-dependent responses of field effect transistors (FETs) with the p-TiO2 films as channel component revealed efficient features. Conclusive results revealed that reliable and reproducible p-type conductivity could be obtained with Ni+2 doped TiO2.

► Solution processed Al+3, Cr+3 and Ni+2 doped TiO2 thin films display p-type conductivity. ► The p-type conductivity was examined through X-ray photoelectron spectroscopy and current–voltage responses. ► The doped thin films were employed as active components in field effect transistor (FET) devices.