Pulsed Laser Deposition of Epitaxial and Polycrystalline Bismuth Vanadate Thin Films

Abstract

We report pulsed laser deposition (PLD) synthesis of epitaxial and polycrystalline monoclinic bismuth vanadate (BiVO 4 , 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 575−600°C, and an oxygen pressure of 7.8 mTorr. The volatility of Bi necessitated a large excess (Bi:V = ∼6:1) 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 ∼0.15 and ∼0.05 mA cm −2 at 1.23 V vs RHE under backside AM1.5G illumination with and without a hole scavenger (Na 2 SO 3 ), 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.

Micropatterning of BiVO4 Thin Films Using Laser‐Induced Crystallization

“…[22a,b] Additionally, the crystalline form of the powder is very crucial for further preparation of the thin layers since it enhances the preservation of bismuth and vanadium stoichiometry. However, according to previous studies, the deposition of layers containing volatile species, e.g., Bi might be nonstoichiometric . In our studies, we confirmed the stoichiometry (Bi to V ratio) of as‐deposited films using energy dispersive X‐ray spectroscopy (EDX).…”

“…The properties of BiVO 4 can be modified by layer preparation techniques. Up to date, many approaches for thin film deposition were reported, including drop casting, spray‐, dip‐, or spin‐coating of BiVO 4 precursor solutions, pulsed laser deposition (PLD) technique, electrochemical deposition and reactive sputtering . Unfortunately, in order to obtain the desired monoclinic crystalline structure all these deposition methods require high temperature as high as 500 °C, either in situ or as post‐treatment.…”

Photoelectrochemical Device Designs toward Practical Solar Water Splitting: A Review on the Recent Progress of BiVO4 and BiFeO3 Photoanodes

“…In general, the establishment of epitaxial thin film photoelectrode has been widely recognized to maximize the potential of photoelectrode materials in pursuit of a further breakthrough by exploring its fundamental properties. For that reason, recently, various research on the growth of the epitaxial BiVO 4 have been reported, to explore its fundamental properties for PEC water splitting [13,19,[56][57][58][59][60][61][62][63]. Based on many theoretical predictions, the research related to the growth of the epitaxial monoclinic BiVO 4 (a = 5.1956 Å, b = 5.0935 Å, c = 11.6972 Å, β = 90.387 • ) films have been focused on growth along the c-axis.…”

Recent Advances in BiVO4- and Bi2Te3-Based Materials for High Efficiency-Energy Applications

“…In order to investigate the experimental crystal and electronic structure of monoclinic BiVO 4 , the single crystal BiVO 4 , which possesses good crystallinity and eliminates the structural and electronic defects as well as impurity phases, is required. The vacuum deposition such as sputtering, molecular beam epitaxy, and pulsed laser deposition for the single crystal monoclinic BiVO 4 has been developed recently [18][19][20]. A good lattice match (mismatch less than 1%) of cubic yttrium-stabilized zirconia (YSZ, a = 5.145 Å) was used as substrate for epitaxial growth of high-quality epitaxial monoclinic BiVO 4 (a = 5.1935 Å, b = 5.0898 Å, c = 11.6972, γ = 90.3871) films.…”

“…To date, there are many methods, which have been developed to prepare BiVO 4 photoelectrodes for use in solar water oxidation. The representative synthesis methods are (1) metal organic decomposition (MOD) combining with the spin coating or spray pyrolysis deposition [21][22][23], (2) electrophoretic deposition (EPD) and chemical bath deposition (CBD) [24][25][26][27], and (3) vacuum deposition methods such as sputtering deposition and pulsed laser deposition (PLD) [18][19][20][28][29]. The MOD is a facile method to synthesize BiVO 4 materials for photoelectrodes.…”