研究目的
Investigating the evolution of Bi2Se3 topological phase from Bi diffusion into GeSe2 layer in Bi/GeSe2 heterojunction films induced by light and thermal energy, and studying the resulting changes in structural and optical properties.
研究成果
The research successfully demonstrated the photo- and thermally induced diffusion of Bi into GeSe2, leading to the formation of Bi2Se3 topological phase and changes in optical properties. The decrease in optical band gap and increase in absorption coefficient are attributed to increased disorder and defect states. These findings suggest potential applications in phase change materials and optical devices, with recommendations for future studies to explore broader parameter ranges and other material systems.
研究不足
The study is limited to specific annealing temperatures (200°C and 250°C) and laser parameters (532 nm, 50 mW cm?2), which may not cover all possible conditions. The use of glass substrates and thermal evaporation might introduce constraints in scalability or application in other environments. Potential optimizations could include varying diffusion parameters or exploring other metal/chalcogenide combinations.
1：Experimental Design and Method Selection:
The study involved thermal evaporation for film deposition, followed by thermal annealing and laser irradiation to induce diffusion. Characterization techniques included XRD, EDAX, SEM, UV-Vis-NIR spectroscopy, and Raman spectroscopy to analyze structural and optical changes.
2：Sample Selection and Data Sources:
Thin films of GeSe2 (1000 nm) and Bi/GeSe2 (8 nm Bi) were deposited on glass substrates. Samples included as-deposited, annealed at 200°C and 250°C for 2 hours, and illuminated with a 532 nm laser for 3 hours at 50 mW cm?2 intensity.
3：List of Experimental Equipment and Materials:
Equipment included a Hind High Vacuum coating unit (Model 12A4D) for deposition, XRD with Cu-Kα radiation (Bruker D8 Advanced), EDAX with SEM attachment, UV-Vis-NIR spectrometer (Bruker Optics IFS66v/S), and Raman spectrometer (LabRAM HR system). Materials included Bi and GeSe2 for film preparation.
4：Experimental Procedures and Operational Workflow:
Films were deposited at room temperature with a base pressure of ~5×10?? Torr and deposition rate of 5 nm/s. Substrates were rotated for uniformity. Thickness was monitored. Annealing and irradiation were performed, followed by characterization using the specified techniques.
5：Data Analysis Methods:
Optical parameters (absorption coefficient, band gap, Tauc parameter, Urbach energy) were calculated from transmission data. Crystallite size was estimated using Scherrer's formula from XRD data. Raman spectra were analyzed for vibrational modes.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容
