InZnON-based Thin Film Transistor for the Development of New Type Photo Detec-tors with a Colloidal Quantum Dots Sensitive Layer

Abstract

Some applications of thin film transistors (TFTs) need the bottom-gate architecture and unpassivated channel backside. In present work, we propose rather simple way to fabricate nitrogen doped InZnO-based TFT by DC reactive magnetron sputtering technique. The moderate nitrogen doping of the channel's semiconductor layer is studied in terms of the reproducibility and stability device's electrical characteristics. When nitrogen concentration in gas mix reaches the upper level of 71 % the best TFT parameters are achieved such as VON = -0.3 V, μ = 12 cm2/Vs, SS = 0.5 V/dec. The TFTs operate in depletion mode exhibiting high turn on/turn off current ratio more than 106. It is shown that the oxidative post-fabrication annealing at 250 °C in pure oxygen and next ageing in dry air for several hours provide highly stable operational characteristics under negative and positive bias stresses despite open channel backside. The prospects of using the thin-film transistor for the new type of photo detectors with a colloidal quantum dots (CQDs) sensitive layer are demonstrated. The solution-cast colloidal-quantum-dots were decorated on the nitrogen doped InZnO layer by spin-coating method. N-type CdSe/ZnS CQDs modified by the ligand (pyridine) are utilized as electron donor to inject electron to the channel layer. Higher photocurrent responsibility about 104 A/W at incident monochromatic light 405 nm is reached for hybrid phototransistor.