High-Performance UV Photodetectors Using Oriented WO₃ Thin Films Grown at Low Temperature in Open Atmosphere

Tungsten oxide (WO₃), an n-type semiconductor, has many potential applications, e.g. electrochromic devices, photodetectors, photocatalysts, supercapacitors, memristors, electrolyte-gated transistors, etc. In this work, we demonstrate ultraviolet (UV) responsivity in photodetector devices as an exemplar application of WO₃ thin films via a CMOS-compatible atmospheric pressure-spatial chemical vapour deposition (AP-SCVD) method. Films grown on Si at 320°C were conformal over cm², and their orientations were continuously tuned by controlling the deposition rate using unique parameters of AP-SCVD. Even though the films were grown in open atmosphere and did not undergo any further annealing, they showed high responsivity (10^-3A/W) in short response time (3.6 s), comparable to the performance of vacuum- or solution- grown films post-processed at temperatures of up to 600°C. More broadly, the films deposited by AP-SCVD have very strong potential for the wide-ranging applications of WO₃.