- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
On the Effect of Thin Film Growth Mechanisms on the Specular Reflectance of Aluminium Thin Films Deposited via Filtered Cathodic Vacuum Arc
摘要： The optimisation of the specular reflectance of solar collectors is a key parameter to increase the global yield of concentrated solar power (CSP) plants. In this work, the influence of filtered cathodic vacuum arc deposition parameters, particularly working pressure and deposition time, on the specular and diffuse reflectance of aluminium thin films, was studied. Changes in specular reflectance, measured by ultraviolet–visible and near-infrared spectroscopy (UV-vis-NIR) spectrophotometry, were directly correlated with thin film elemental concentration depth profiles, obtained by Rutherford backscattering spectrometry (RBS), and surface and cross-sectional morphologies as measured by scanning electron microscopy (SEM) and profilometry. Finally, atomic force microscopy (AFM) provided information on the roughness and growth mechanism of the films. The two contributions to the total reflectance of the films, namely diffuse and specular reflectance, were found to be deeply influenced by deposition conditions. It was proven that working pressure and deposition time directly determine the predominant factor. Specular reflectance varied from 12 to 99.8% of the total reflectance for films grown at the same working pressure of 0.1 Pa and with different deposition times. This transformation could not be attributed to an oxidation of the films as stated by RBS, but was correlated with a progressive modification of the roughness, surface, and bulk morphology of the samples over the deposition time. Hence, the evolution in the final optical properties of the films is driven by different growth mechanisms and the resulting microstructures. In addition to the originally addressed CSP applications the potential of the developed aluminium films for other application rather than CSP, such as, for example, reference material for spectroscopic diffuse reflectance measurements, is also discussed.
关键词： structural characterisation,total and specular reflectance,filtered cathodic vacuum arc,thin film deposition conditions
更新于2025-10-22 19:40:53
-
Optical, electrical, structural and magnetic properties of BiSe thin films produced by CBD on different substrates for optoelectronics applications
摘要： BiSe thin films have been grown on substrates as PMMA, ITO, glass and Si wafer by using chemical bath deposition (CBD) method. Deposition temperature and time and pH are kept to be constant during the production of the thin films. The thickness of BiSe thin films, which are produced on ITO, glass, PMMA and Si wafer substrate are 513, 468, 1039 and 260 nm, respectively. According to GAXRD results, the films, which are grown on glass and PMMA substrate, have amorphous structure, but, the films, which are grown on ITO and Si wafer substrate, have peaks of Bi2Se3 crystal. Grain sizes, crystallization number per unit area and dislocation density for ITO and Si wafer substrate are calculated as 112.40 nm and 43.04 nm; 2.25×10?5 and 7.91×10?5 (1/nm2), respectively. The contact angles and critical surface tension of distilled water, ethylene glycol, formamide and diiodamethane liquids for thin films grown on glass, ITO, PMMA and Si wafers were obtained by the Zisman method. The % transmittance and % reflectance values of thin films grown on glass, ITO, PMMA are calculated as % T: 79.90, 92.76 and 67.37; % R: 6.18, 2.07 and 10.59, respectively. Eg values of thin films grown on glass, ITO, PMMA are calculated as Eg=1.92; 2.18; 1.60 eV. The extinction coefficients, refractive indexes and relative dielectric constants of thin films grown on glass, ITO, PMMA are calculated as k=0.007; 0.002 and 0.012; n=1.65; 1.34 and 1.96; ε1=0.271; 0.083 and 0.528 respectively. Sheet resistance, hall mobility, sheet carrier densities, bulk carrier densities and conductivity types for glass, ITO, PMMA and Si are 6.52×107, 6.65×101, 1.09×108 and 6.45×102 (Ω/cm2); 2.38, 1.21×10?1, 5.34 and 1.52 (cm2/V.s); 4.01×1010, 7.71×1017, 1.06×1010 and 6.34×1015 (cm?2); 4.58×1014, 1.50×1022, 1.02×1014 and 2.89×1020 (cm?3); p, n, p and p, respectively. In addition, I–V characteristics and changes of magnetoresistance values versus magnetic field of the thin films are obtained by Van der Pauw method and HEMS.
关键词： magnetoresistance,thin film deposition,optical band gap,carrier density,surface properties,crystal growth
更新于2025-09-23 15:21:21
-
Mechanism of Liquid-Phase Reductive Thin-Film Deposition under Quasiballistic Electron Incidence
摘要： Highly reducing activity of quasiballistic hot electrons emitted from a nanocrystalline silicon (nc-Si) diode is veri?ed in terms of liquid-phase thin ?lm deposition. Incident electrons reduce positive ions in salt solutions coated on a target substrate, and then result in deposition of thin metal (Cu) and semiconducting (Si, Ge, and SiGe) ?lms. This mechanism is investigated here throughout the process from electron incidence to thin ?lm deposition. Thermodynamic criterion deduced from classical nucleation theory suggests that the output electron energy of the nc-Si emitter is suitable for promoting preferential reduction of target ions in solutions leading to the nuclei formation. In accordance with mass-transport analyses on generated nanoclusters, the most primary factor of thin ?lm growth is the dose of incident electron. The formulated deposition rate rapidly increases and reaches a stationary value within 0.1 s after electron incidence. The theoretical dependency of the thin ?lm thickness on the electron incidence time is consistent with the experimental results. Speci?c features of this scheme as an alternative approach for thin ?lm deposition are discussed in comparison with the conventional dry and wet processes.
关键词： nanocrystalline silicon diode,quasiballistic hot electrons,mass-transport analyses,thermodynamic criterion,liquid-phase thin film deposition
更新于2025-09-23 15:21:21