Effects of sputtering deposited homoseed layer microstructures on crystal growth behavior and photoactivity of chemical route-derived WO3 nanorods

• Published in: CrystEngComm 2019, Vol.21 (38), p.5779-5788
• Main Authors: Yuan-Chang, Liang, Chen-Shiang, Hung
• Format: Article
• Language: English
• Subjects: Arrays; Crystal growth; Crystal structure; Crystallinity; Crystals; Direct current; Grain size; Morphology; Nanorods; Organic chemistry; Sputtering; Substrates; Thin films; Tungsten oxides
• ISSN: 1466-8033
• DOI: 10.1039/c9ce00779b

The crystal growth properties of hydrothermally derived tapered WO3 nanorod arrays were investigated using predeposited homoWO3 thin films as seed layers. The WO3 seed layers with various microstructures were deposited using direct current and radio-frequency sputtering techniques with and without subsequent postannealing procedures at 600 °C. The seed layers prepared using different sputtering methods and annealing treatments had different surface grain sizes and crystallinities, and these characteristics of the prepared seed layers substantially influenced the morphology of the WO3 nanorod arrays subsequently grown on the layers. The amorphous homoWO3 seed layer led to the growth of WO3 nanorods, which were dispersedly stacked on the substrate with a random orientation. By contrast, the vertically aligned WO3 nanorods were successfully grown on the crystalline homoWO3 seed layers. A larger surface grain size of the crystalline WO3 seed layer decreased the bundle degree of the adjacent WO3 nanorods. Moreover, the larger surface grain size improved the vertical alignment degree of the as-synthesized WO3 nanorods. In this study, the WO3 nanorods exhibited superior photoactivated properties when grown on a homoseed layer with a surface grain size of larger than 114 nm.