Modification of charge transport in nanostructured TiO_2−x Schottky diodes via post fabrication annealing

Abstract

An ordered, crack-free array of anatase TiO2 nanotubes were prepared via anodization and annealing at 550 °C. Oxygen vacancies are known to improve photocatalytic activity in TiO2 and were introduced using a facile low vacuum annealing. Stoichiometric and nonstoichiometric films were followed by a conformal Pt deposition at 250 °C using atomic layer deposition resulting in a current rectifying device, or Schottky diode. Here, we investigated the current–voltage effects of a post thermal treatment using 350 °C and 400 °C. This paper presents reproducible improvements in the charge transport behavior after a 350 °C post-fabrication annealing process. Oxygen vacancies resulted in the formation of a shunt resistance behavior of 105 Ω and no overall performance improvements compared to stoichiometric films. Additionally, thermal treatments offered trap-based shifts from multiple trap distributions to a single trap distribution. This work hereby provides valuable experimental observations into understanding the effects of oxygen vacancies and effectively modifying the electronic properties of a conformal Pt/TiO2−x nanostructured junction using a facile post-thermal treatment.