研究目的
To properly discuss the issue of adherence of chemical-solution-deposited chalcogenide films, specifically CdS, by examining the effects of Cd2+ concentration, substrate surface chemistry, and reaction temperature.
研究成果
The adherence of CdS thin films depends on the formation of surface intermediate entities, which is influenced by substrate surface chemistry (e.g., tin content), Cd2+ concentration, and reaction temperature. Conditions that promote these entities (high reagent concentration, reactive surface sites like SnO2, low temperature) lead to good adherence. The proposed reaction scheme provides a basis for understanding and improving adherence in chemical bath deposition.
研究不足
The study is limited to inorganic substrates (float glass, ITO, silicon wafers) and does not cover polymer or metal substrates. The reaction scheme does not consider film growth mechanisms, which are noted for future work. The use of low-cadmium formulations may lead to poor adherence on certain substrates, and methods to improve this without increasing costs or waste are not fully resolved.
1：Experimental Design and Method Selection:
The study used chemical bath deposition (CBD) to deposit CdS thin films on various substrates (float glass, ITO, silicon wafers) under controlled conditions. Two reaction solutions were prepared: a concentrate solution with 12 mM CdCl2 and a dilute solution with 6 mM CdCl2, both containing Na3C6H5O7, NaOH, and thiourea. The deposition was carried out at temperatures ranging from 30 to 70°C for different times.
2：Sample Selection and Data Sources:
Substrates included Corning float glass microscope slides (with tin-bath and atmosphere sides), indium tin oxide (ITO) surfaces, and silicon wafers. These were cleaned and characterized using X-ray photoelectron spectroscopy (XPS) to analyze surface chemistry.
3：List of Experimental Equipment and Materials:
Equipment included a PerkinElmer Physical Electronics PHI 5100 spectrometer for XPS measurements, profilometry for thickness measurements, and standard laboratory glassware for deposition. Materials included CdCl2 (Spectrum,
4：0% purity), Na3C6H5O7·2H2O (Fermont, 7% purity), NaOH (J.T. Baker, 6% purity), thiourea (Fermont, 9% purity), and distilled water. Experimental Procedures and Operational Workflow:
Substrates were cleaned and immersed in the reaction solutions at specified temperatures. Deposition times varied from minutes to hours. After deposition, films were rinsed and dried. Adherence was tested by visual inspection and mechanical actions like water jet or wet cotton cleaning. Thickness was measured using profilometry.
5：Data Analysis Methods:
XPS data were analyzed to determine atomic composition and chemical states. Adherence was qualitatively assessed, and film thickness was plotted against time and temperature. Statistical analysis was not explicitly mentioned, but uncertainties were assessed with 95% confidence for XPS data.
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