Crystal phase content-dependent functionality of dual phase SnO(2)–WO(3) nanocomposite films via cosputtering crystal growth

In this study, crystalline SnO(2)–WO(3) nanocomposite thin films were grown through radio-frequency cosputtering of metallic Sn and ceramic WO(3) targets. The W content in the SnO(2) matrix was varied from 5.4 at% to 12.3 at% by changing the WO(3) sputtering power during thin-film growth. Structural analyses showed that increased WO(3) phase content in the nanocomposite films reduced the degree of crystallization of the SnO(2) matrix. Moreover, the size of the composite films' surface crystallites increased with WO(3) phase content, and the large surface crystallites were composed of numerous nanograins. Addition of WO(3) crystals to the SnO(2) matrix to form a composite film improved its light harvesting ability. The SnO(2)–WO(3) nanocomposite films exhibited improved photodegradation ability for Rhodamine B dyes compared with their individual constituents (i.e., SnO(2) and WO(3) thin films), which is attributable to the suitable type II band alignment between the SnO(2) and WO(3). Moreover, an optimal WO(3) phase content (W content: 5.4 at%) in the SnO(2) matrix substantially enhanced the ethanol gas-sensing response of the SnO(2) thin film. This suggested that the heterojunctions at the SnO(2)/WO(3) interface regions in the nanocomposite film considerably affected its ethanol gas-sensing behavior.