Novel approach to synthesize morphology variant tungsten oxide thin films for efficient chemical sensing

A new approach has been designed to synthesize and modify the morphology of high quality nanocrystalline tungsten oxide (WO₃) thin films using hot filament chemical vapor deposition (HFCVD) technique. The thin films were successfully synthesized having completely distinct morphologies using different processing conditions in very short duration of time 4–6 min. Two types of morphologies resembling a broccoli decorated with WO₃ nanograins (BWN) and another having faceted, pyramidal growth of WO₃ nanograins (PWN) were obtained. Both as-prepared films displayed excellent uniformity and exhibited the formation of standard monoclinic structure without undergoing any additional calcination/sintering. The morphology variant WO₃ thin films were applied as sensing electrodes to detect toxic chemical such as diethylamine (DEA) chemical. Due to smaller particle size, higher surface area and higher oxygen contents, the BWN thin film offered promising performance in DEA sensing with good sensitivity of ∼3.5 μAμM⁻¹cm⁻² and fast response ∼10 s.