Enhanced UV photodetector performance in bi-layer TiO2/WO3 sputtered films

In this work, we describe the efficiency of ultra-violet (UV) photodetector performance through RF magnetron sputtered TiO2/WO3 bi-layer thin films. The structural, chemical, morphological and photocurrent response properties of as-grown TiO2, WO3 and bi-layer TiO2/WO3 films were systematically studied. Herein, the merit of enhanced oxygen vacancies in the TiO2/WO3 bi-layer plays a crucial role in photoresponse which is due to the shift of W4f spectrum towards lower binding energy side. Consequently, the addition of WO3 layer on TiO2 might be responsible for the superior charge carrier generation when light is illuminated on bi-layer thin film. Besides, linear I-V characteristics of as-resulted samples confirm the ohmic-contact behaviour between the photodetector material and the electrode. The bi-layer of TiO2/WO3 sample generates more electrons and these are might be trapped at Fermi-level of the film surface and it causes for the suppression of the charge carriers recombination rate. As a result, by fine tuning of the bi-layer of TiO2/WO3 structure provides a promising UV photodetector performance than the single-layer of TiO2 and WO3.