A well-designed procedure, including ion beam sputtering of aluminium (Al)–tungsten trioxide (WO₃) composite films, annealing at an elevated temperature and dealloying of aluminium component, was carried out in sequence to fabricate porous nanocrystalline tungsten trioxide thin films. The texture, morphology and electrical and optical properties of the tungsten trioxide thin films were each characterised. It was found that when the annealing temperature of the aluminium–tungsten trioxide composite film reached 550°C, the obtained tungsten trioxide thin film after dealloying was nanocrystalline with a more pronounced porous structure. Electrical property tests showed that in contrast to that of amorphous tungsten trioxide films, the resistance of the porous nanocrystalline tungsten trioxide film was much greater, with a positive temperature coefficient of resistance (TCR) of +4.1 × 10⁻²/°C at temperatures of −10 to 5°C and a negative TCR of −2.4 × 10⁻²/°C at temperatures of 5 to 30°C. It was further demonstrated by ultraviolet–visible spectroscopy that compared with amorphous tungsten trioxide films, the porous crystalline tungsten trioxide film had much higher transmittance at the wavelength of visible light and a larger forbidden band width of 2.75 eV. Therefore, the porous nanocrystalline tungsten trioxide film exhibits unique or excellent electrical and optical properties, which indicate new potential applications in the fields of photoelectric devices and thermistors.

中文翻译：

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多孔纳米晶 WO3 薄膜：制造、电学和光学特性

精心设计的程序，包括铝 (Al)-三氧化钨 (WO ₃) 复合薄膜，依次进行高温退火和铝组分脱合金，以制备多孔纳米晶三氧化钨薄膜。三氧化钨薄膜的质地、形态以及电学和光学性质均被表征。发现当铝-三氧化钨复合薄膜的退火温度达到550℃时，脱合金后得到的三氧化钨薄膜呈纳米晶，多孔结构更加明显。电性能测试表明，与非晶三氧化钨薄膜相比，多孔纳米晶三氧化钨薄膜的电阻要大得多，正电阻温度系数（TCR）为+4.1×10 ^-2/°C 在 -10 至 5°C 的温度下和负 TCR 为 -2.4 × 10 ^-2 /°C 在 5 至 30°C 的温度下。紫外-可见光谱进一步证明，与非晶三氧化钨薄膜相比，多孔结晶三氧化钨薄膜在可见光波长下具有更高的透射率和更大的2.75 eV禁带宽度。因此，多孔纳米晶三氧化钨薄膜表现出独特或优异的电学和光学性能，这表明在光电器件和热敏电阻领域具有新的潜在应用。