研究目的
Investigating the growth, morphology, and crystal structure of electrodeposited Bi2Se3 films on different substrates (n-Si, Au, Ru) to understand the influence of the substrate on film properties and phase formation.
研究成果
The substrate significantly influences the growth, morphology, and crystal structure of electrodeposited Bi2Se3 films. Pure orthorhombic phase forms on n-Si with high Faradaic efficiency, while mixed or rhombohedral phases form on Au and Ru with lower efficiencies. Annealing transforms phases to rhombohedral, with onset around 125°C. Room temperature deposition favors metastable orthorhombic phase, highlighting the role of substrate epitaxy and deposition parameters in controlling film properties for potential applications in optoelectronics.
研究不足
The study is limited to specific substrates (n-Si, Au, Ru) and deposition conditions; results may not generalize to other substrates or methods. Faradaic efficiencies are indicative due to morphological variations and voiding. The surface energy of Bi2Se3 is estimated from elemental values, lacking direct measurement. Epitaxial relationships are hypothesized but not fully confirmed for all substrates.
1:Experimental Design and Method Selection:
Electrodeposition of Bi2Se3 films using potentiostatic deposition from acidic baths with varying Bi and Se precursor concentrations. Characterization includes cyclic voltammetry, SEM, EDS, XRD, and Raman spectroscopy to analyze growth, morphology, composition, and crystal structure. In-situ Raman spectroscopy is used to study phase transformation during annealing.
2:Sample Selection and Data Sources:
Substrates used are n-type Si (100), polycrystalline Au (111), and polycrystalline Ru wafers. Films are deposited at specific potentials vs. SCE, with charge densities (Qd) ranging from 1 mC/cm2 to 2 C/cm2.
3:List of Experimental Equipment and Materials:
Equipment includes FEI Quanta 650 and LV200 SEMs with EDS, PANalytical Empyrean X-ray diffractometer, Renishaw Raman spectrometer with 514 nm laser, hot stage for in-situ annealing. Materials include Bi(NO3)3, SeO2, HNO3, HF solution, GaIn eutectic, Kapton tape.
4:Experimental Procedures and Operational Workflow:
Substrates are prepared by etching in HF to remove oxide layers. Electrodeposition is performed at specified potentials. Films are characterized for thickness, composition, and structure. Annealing is done in nitrogen atmosphere with temperature ramping and holding.
5:Data Analysis Methods:
Faradaic efficiency is calculated from film thickness and composition. XRD patterns are matched to crystal phases. Raman spectra are analyzed for vibrational modes indicative of phase changes.
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