LaFeO3thin films were successfully epitaxially grown on single-crystalline SrTiO3substrates by the one-step hydrothermal method at a temperature of 320 °C in a 10 mol/L KOH aqueous solution using La(NO3)3and Fe(NO3)3as the raw materials. The growth of the films was consistent with the island growth mode. Scanning electronic microscopy, elemental mapping, and atomic force microscopy demonstrate that the LaFeO3thin films cover the SrTiO3substrate thoroughly. The film subjected to hydrothermal treatment for 4 h exhibits a relatively smooth surface, with an average surface roughness of 10.1 nm. X-ray diffraction in conventional Bragg–Brentano mode shows that the LaFeO3thin films show the same out-of-plane orientation as that of the substrate (i.e., (001)LaFeO3||(001)SrTiO3). The in-plane orientation of the films was analyzed by φ-scanning, revealing that the orientational relationship is [001]LaFeO3||[001]SrTiO3. The ω-rocking curve indicates that the prepared LaFeO3films are of high quality with no significant mosaic defects.
Beilei Yuan,Haoming Wei,Jingwei Li,Yu Zhou,Fan Xu,Jinkai Li,Bingqiang Cao
In this paper, inorganic halide perovskite cesium lead bromide (CsPbBr3) films are epitaxially grown on (100)-oriented SrTiO3 substrates by pulsed laser deposition (PLD). This method has the distinctive advantages to grow high-quality films with a precise composition, designed crystalline orientation, and controlled uniform thickness. By optimizing the substrate temperatures and laser pulse numbers, (100)-CsPbBr3 films with uniform morphology are grown on a SrTiO3 substrate via a cubic-on-cubic epitaxial growth mode, which is proven by XRD investigation. Detailed photophysical spectroscopy study including femtosecond transient absorption spectra and detailed low-temperature photoluminescence spectra indicate that such epitaxial CsPbBr3 films are of very low defects in the bandgap. The temperature-dependent resistivity measurement reveals that the epitaxial CsPbBr3 films show a typical thermally activated carrier behavior with a bandgap value of 2.37 eV, which is very consistent with the optical result and indicates a quasi-intrinsic semiconductor nature of such an epitaxial film. Our results confirm that CsPbBr3 films with high crystal quality and lower defect density can be epitaxially grown with PLD for further superlattices and quantum wells.
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