Tailorable tungsten oxide for near-IR photonics and transparent-conductive films.

Tungsten oxide is a polymorph wide-bandgap semiconductor, with multiple possible stable stoichiometries at normal conditions. Physical characteristics, including electrical, optical, and dielectric properties, are versatile and can be manipulated through stoichiometric and structural tailoring. In this sense tungsten oxide can contribute its role to a broad range of advanced applications. In our study, optical-grade tungsten oxide thin films were fabricated by non-reactive RF-sputtering and their compositional ratio as well as structural phase were adjusted by annealing in air. Analyses were performed to evaluate performances of the as-prepared and the thermally treated tungsten oxide films in different physical aspects. Results showed that tungsten oxide films may exhibit good electrical conductivity in the presence of high optical transparency in the near-IR optical range. Besides, an effective enhancement of near-IR optical field is numerically found on tungsten oxide films when integrated into 1-D photonic band-gap structures. Thus, we quest possible applications of tungsten oxide films to the fields of 1-D photonics and transparent-conductive films in the near-IR range.