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VO <i> <sub/>n</sub></i> Complexes in RTA Treated Czochralski Silicon Wafers Investigated by FTIR Spectroscopy
摘要： Oxygen-vacancy complexes formed after rapid thermal annealing in silicon wafers were investigated by FTIR spectroscopy at 6 K. It was found that VO4 is the only detectable complex. The concentration of VO4 complexes increases with increasing temperature of RTA treatment in the temperature range between 1250?C and 1400?C. The concentration at maximal temperature is equal to 4.5 × 1013 cm?3. The experimental results were compared with concentrations of VOn complexes in silicon wafers obtained using ab-initio calculations combined with rate equation modelling. The simulated concentration of VO4 corresponds well to the measured concentration. The bulk microdefect density increases with increasing VO4 concentration. The vacancies stored in VOn complexes after RTA are slowly released during further annealing and enhance oxide precipitation.
关键词： VO4 complexes,silicon wafers,Rapid thermal annealing,FTIR spectroscopy,oxygen precipitation
更新于2025-09-09 09:28:46
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Highly Transparent Conducting Indium Tin Oxide Thin Films Prepared by Radio Frequency Magnetron Sputtering and Thermal Annealing
摘要： High-quality ITO (indium tin oxide) films were grown by radio frequency (RF) magnetron sputtering and post thermal annealing. Both the thermal annealing temperature and the atmosphere significantly influenced the optical and electrical properties of ITO films. The as-grown 110-nm-thick ITO film showed an optical transmittance of 34.2% at a wavelength of 550 nm and electrical resistivity of 9.2 × 10?4 Ωcm. Notably, the ITO films annealed at 850 °C for 1 min in nitrogen ambient led to a significantly improved optical transmittance (97.3%) and the low electrical resistivity of 1.3 × 10?4 Ωcm, while those annealed in air or oxygen ambient produced poorer electrical properties despite their good optical transmittance owing to the presence of oxygen. The high quality of the ITO film annealed in nitrogen could be attributed to the combined effects of effective suppression of oxygen incorporation into films (thus maintaining oxygen vacancies in the ITO film), enhanced Sn doping, and improved the crystallinity with larger grain size.
关键词： ITO,RF-Magnetron Sputtering,Optical Transmittance,Rapid Thermal Annealing
更新于2025-09-04 15:30:14
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Influence of Post-deposition Heat Treatments on the Optical Properties of Chemically Deposited Nanocrystalline TiO2 Thin Films
摘要： The aim of this study is to investigate the potentials of TiO2 thin films for device applications. Nanocrystalline single phase of rutile TiO2 thin films have been prepared by Chemical Bath Deposition (CBD) technique at bath temperature range from 75-80°C, keeping other deposition variables constant. The films were then subjected to post-deposition heat treatments with annealing temperatures in the range 373 to 673 K. The optical characterisation was done using the Elmer Lambda-2 spectrometer to investigate the transmittance and absorbance versus wavelength measurements. The data obtained from the transmittance and absorbance measurements were used to deduce the important optical constants. The results show that the energy bandgap was direct, with values in the range ≤1.8 eV for the as-deposited layers and ≥2.2 eV for the annealed layers. At lower temperatures, the band gaps of the annealed samples did not differ significantly from the energy gap (1.8 eV) of the as-deposited film. At higher thermal treatment, the energy gaps increased with the increase in annealing temperatures and a maximum of 2.2 eV for the energy gap was determined for TiO2 film annealed at 673 K. The values of the energy bandgap obtained in study, are within the range suitable for application in photovoltaic solar cell devices and in related photonic applications.
关键词： thermal annealing,Energy band gap,solar cells,TiO2
更新于2025-09-04 15:30:14
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Combined mechanochemical/thermal annealing approach for the synthesis of Co9Se8 with potential optical properties
摘要： Synthesis of Co9Se8 phase from metallic cobalt and selenium powders by one-pot mechanochemical synthesis in a planetary ball mill and subsequent thermal treatment in argon atmosphere is reported. Crystal structure and morphology of the products were characterized by X-ray diffraction, specific surface area measurements, and transmission electron microscopy. Our study revealed that only mixture with excess of Co resulted in the formation of higher fraction of the Co9Se8 phase. While milling of Co and Se in 13.5:8 ratio resulted in the synthesis of nanocrystalline hexagonal CoSe (freboldite) and only around 13?wt.% of the targeted Co9Se8 phase, additional isothermal treatment at 450?°C increased yield of the Co9Se8 phase to more than 70%. Optical properties of the product with the highest Co9Se8 fraction showed broad absorption in whole UV–Vis optical region and band-gap energy of 1.93?eV, blue-shifted relative to the bulk Co9Se8. Both UV–Vis and photoluminescence spectra indicated quantum size effect of the finest nanocrystals in Co9Se8 product. The new combined approach represents a simple, fast, and easy up-scalable route for the synthesis of Co9Se8.
关键词： thermal annealing,optical properties,mechanochemical synthesis,Co9Se8,quantum size effect
更新于2025-09-04 15:30:14