Electrical and optical properties of titanium oxynitride thin films

A TiNxOy (TiNO) material system has been synthesized in thin film form for the first time using a pulsed laser deposition process. X-ray diffraction and X-ray photoelectron spectroscopy measurements have been carried out to show partial oxidation of TiN to TiNO. The current (I)-voltage (V) characteristics recorded from TiNO films sandwiched between indium tin oxide (ITO) and gold (Au) layers and/or copper (Cu) electrodes have shown that the I–V curves lie in the first and third quadrants (i.e., both I and V are either positive or negative) in the dark conditions, while the I–V curves lie in the second and fourth quadrants (i.e., I and V with opposite sign) in the illuminated conditions. The positive sign of power (I × V = Positive) under dark conditions indicates dissipation of power in the TiNO system, while the negative sign of the power (I × V = Negative) under optical illumination indicates the power generation capability of TiNO system. The bandgap of the TiNO thin film samples, measured using ultra violet (UV)–visible (400–800 nm) spectroscopy, was found to be ~ 1.6 eV. As the number of photocatalysts/semiconductors that are active under the visible light irradiation is very limited, our approach to develop a unique visible-light-driven TiNO photoactive material system can open a new avenue for the realization of novel optical devices.