Probing the trap levels in the wide bandgap TiO₂ by Deep Level Transient Spectroscopy

Titanium dioxide (TiO₂) is an important material due to its application in various fields of science and technology, including medicine. However, it suffers from an enormous amount of native defects. Moreover, many of the exciting properties, such as resistive switching and intrinsic n-type conductivity, are governed by these. Hence, a genuine understanding of these defects will be essential and provide insight into designing the new devices based on TiO₂. In this, work we have fabricated a TiO₂ thin film-based Metal - Oxide - Semiconductor (MOS) capacitor to study the deep defects present in wide bandgap TiO₂ by Deep Level Transient Spectroscopy (DLTS) method. DLTS is a valuable tool for precisely studying the various defects parameters such as activation energy, capture-cross section, and density of traps. The analysis reveals five peaks in the DLTS spectrum, and in light of theoretical reports, we believe these belong to the oxygen vacancies and Ti interstitial related defects. These defects levels are located at 0.66 – 1.07 eV below the conduction band edge of TiO₂. The capture cross-sections and defect densities are in the range of 4.3×10^-17 – 3.2×10^-19 cm² and 1.9×10¹⁴ – 2.7×10¹⁶ cm^-3, respectively.