Pulsed Laser Deposition of Epitaxial and Polycrystalline Bismuth Vanadate Thin Films

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• 作者：Alexander J. E. Rettie ; Shirin Mozaffari ; Martin D. McDaniel ; Kristen N. Pearson ; John G. Ekerdt ; John T. Markert ; C. Buddie Mullins
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：November 20, 2014
• 年：2014
• 卷：118
• 期：46
• 页码：26543-26550
• 全文大小：425K
• ISSN：1932-7455

文摘

We report pulsed laser deposition (PLD) synthesis of epitaxial and polycrystalline monoclinic bismuth vanadate (BiVO₄, BVO) thin films. X-ray diffraction (XRD), atomic force microscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy were used to characterize the samples. Epitaxial, c-axis oriented growth was achieved using single crystal yttria-stabilized zirconia (100), a substrate temperature of 575鈥?00 掳C, and an oxygen pressure of 7.8 mTorr. The volatility of Bi necessitated a large excess (Bi:V = 鈭?:1) of this element in the ceramic targets to obtain stoichiometric films. XRD confirmed a BVO (001)||YSZ (001) and BVO [100]||YSZ [100] epitaxial relationship. Film growth was 3-D, and the morphology was discontinuous, consisting of irregular, smooth grains. Additionally, dense, continuous polycrystalline films were deposited on fluorine-doped tin oxide (FTO) on glass substrates at room temperature with stoichiometric targets and postdeposition annealing in air. Evaluation of these samples as photoanodes yielded photocurrents of 鈭?.15 and 鈭?.05 mA cm^鈥? at 1.23 V vs RHE under backside AM1.5G illumination with and without a hole scavenger (Na₂SO₃), respectively. We argue that the photocurrents are due to the high oxygen content inherent in the PLD process and suggest that these continuous films may be well-suited to investigating oxygen-related defects in BVO.