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Evolutions on surface chemistry, microstructure, morphology and electrical characteristics of SnO2/p-Si heterojuction under various annealing parameters
摘要： The influences of annealing temperature and ambient on surface chemistry, microstructure, morphology and electrical characteristics of Tin Oxide (SnO2)/Si heterojuctions are systematically identified. Metallic and oxygen deficient SnO2-x bonds have been consistently treated to stoichiometric SnO2 with annealing temperatures up to 600 0C in nitrogen environment. It has been observed that further increase in the annealing temperature causes the formation of the silicate layer. Presence of hydrogen in forming gas environment causes formation of the oxygen deficient SnO2-x, while the presence of the oxygen contributes to the formation of the stoichiometric SnO2 layer in oxygen annealing ambient. Parasitic phases significantly affect the crystalline structure of the films. Surface roughness of the samples decreases up to 1.02 nm which is strongly correlated with stress and strain on the film. On the other hand, oxidations of the dangling bonds and/or hydrogen diffusion cause variations in the total dipole moments which significantly change the capacitance. Depending on the annealing parameters, effective charge densities and interface trap densities decrease to 1011 cm-2, while the ideality factor and barrier potential are improved to 1.43 and 0.59 eV, respectively. Owing to the crystallization of the SnO2 layer, leakage current increase at low temperature annealing. However, passivation of the dangling bonds becomes more effective than phase crystallization at higher temperatures on the leakage characteristics. The current study shows that any changes in the surface chemistry directly affect the device performance.
关键词： Tin Oxide,XPS,Oxide Films.,Heterojuction,Surface Chemistry,Annealing
更新于2025-09-10 09:29:36
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Graphene oxide enwrapped polyimide composites with efficient photocatalytic activity for 2,4-dichlorophenol degradation under visible light irradiation
摘要： In this study, graphene oxide (GO) enwrapped polyimide (PI) composite photocatalyst was prepared via a facile ultrasonic chemical method. The as-synthesized GO/PI hybrid composite can serve as a stable metal-free photocatalyst for 2,4-dichlorophenol (2,4-DCP) degradation under visible-light irradiation. After loading of GO, the GO/PI composites displayed enhanced photocatalytic performance. The apparent rate constant for 2,4-DCP degradation of the composites was approximately 4.5 times as high as that of bare PI. The results of radical trapping experiments and electron spin resonance indicated that the photogenerated hole (h+) and O2? were the main responsible for the 2,4-DCP degradation. The energy band diagram derived from Mott-Schottky and UV–vis diffuse absorption spectra revealed that the formed heterojunction between PI and GO is type-II. The formed heterojunction with well matched energy levels leads to an efficient injection of photoinduced electrons from PI to GO, and facilitates the separation of photoinduced charge carrier. The combined transient photocurrent and electrochemical impedance spectroscopy results further verified the enhancement was mainly ascribed to the improved charge carrier separation performance of composite.
关键词： Photocatalysis,2,4-dichlorophenol,Heterojuction,Polyimide,GO
更新于2025-09-04 15:30:14