Solution-Processed Neodymium Oxide/ZnO Thin-Film Transistors with Electron Mobility in Excess of 65 cm V⁻¹ s⁻¹

This work reports on solution processed Nd₂O₃ thin films that are deposited under ambient conditions at moderate temperatures of about 400 °C and their implementation as gate dielectrics in thin film transistors employing solution processed ZnO semiconducting channels is also demonstrated. The optical, dielectric, electric, structural, surface, and interface properties of Nd₂O₃ films are investigated using a wide range of characterization techniques that reveal smooth Nd₂O₃ films of cubic structure, wide bandgap (6 eV), high-k (11), and low leakage currents (<0.5 nA cm⁻²). Thin film transistors (TFTs) using ZnO channels show excellent characteristics, such as high electron mobility, in excess of 65 cm² V⁻¹ s⁻¹, high on/off current ratio in the range between 10⁶ and 10⁷, and negligible hysteresis. The devices demonstrate excellent constant bias stress and air stability air, i.e., only a small decrease of the electron mobility and threshold voltage (<12%). In addition, the excellent uniformity and homogeneity that is demonstrated combined with the relatively low deposition temperature (compared with those used with the vast majority of the vacuum based techniques employed) in ambient air on glass substrates indicates the potential for the rapid development of metal oxide-based TFTs employing gate dielectrics also grown from solutions at low manufacturing cost.