Browsing by Subject "Radio frequency magnetron sputtering"

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Open Access
Postdeposition annealing on RF-sputtered SrTiO3 thin films
(AVS Science and Technology Society, 2017) Bayrak, T.; Kizir,S.; Kahveci, E.; Bıyıklı, N.; Goldenberg, E.
Understanding of structural, optical, and electrical properties of thin films are very important for a reliable device performance. In the present work, the effect of postdeposition annealing on stoichiometric SrTiO3 (STO) thin films grown by radio frequency magnetron sputtering at room temperature on p-type Si (100) and quartz substrates were studied. Highly transparent and well adhered thin films were obtained in visible and near infrared regions. As-deposited films were amorphous, while nanocrystalline and polycrystalline phases of the STO thin films formed as a function of annealing temperature. Films annealed at 300 ï¿½C showed nanocrystallinity with some amorphous phase. Crystallization started after 15 min annealing at 700 ï¿½C, and further improved for films annealed at 800 ï¿½C. However, crystallinity reduced for films which were annealed at 900 ï¿½C. The optical and electrical properties of STO thin films affected by postdeposition annealing at 800 ï¿½C: Eg values decreased from 4.50 to 4.18 eV, n(λ) values (at 550 nm) increased from 1.81 to 2.16. The surface roughness increased with the annealing temperature due to the increased crystallite size, densification and following void formation which can be seen from the scanning electron microscopy images. The highest dielectric constants (46 at 100 kHz) observed for films annealed at 800 ï¿½C; however, it was lower for 300 ï¿½C annealed (25 at 100 kHz) and as-deposited (7 at 100 kHz) STO films having ∼80 nm thickness.
Open Access
Structural, optical and electrical characteristics BaSrTiOx thin films: Effect of deposition pressure and annealing
(Elsevier BV * North-Holland, 2017) Bayrak, T.; Ozgit-Akgun, C.; Goldenberg, E.
Among perovskite oxide materials, BaSrTiOx (BST) has attracted great attention due to its potential applications in oxide-based electronics. However, reliability and efficiency of BST thin films strongly depend on the precise knowledge of the film microstructure, as well as optical and electrical properties. In the present work, BST films were deposited at room temperature using radio frequency magnetron sputtering technique. The impact of deposition pressure, partial oxygen flow, and post-deposition annealing treatment on film microstructure, surface morphology, refractive index, and dielectric constants were studied by X-ray diffraction, scanning electron microscopy, spectrophotometry, ellipsometry, photoluminescence, as well as capacitance-voltage measurements. Well-adhered and uniform amorphous films were obtained at room temperature. For all as-deposited films, the average optical transmission was ~ 85% in the VIS-NIR spectrum. The refractive indices of BST films were in the range of 1.90–2.07 (λ = 550 nm). Post-deposition annealing at 800 °C for 1 h resulted in polycrystalline thin films with increased refractive indices and dielectric constants, however reduced optical transmission values. Frequency dependent dielectric constants were found to be in the range of 46–72. However, the observed leakage current was relatively small, about 1 μA. The highest FOM values were obtained for films deposited at 0.67 Pa pressures, while charge storage capacity values increased with increased deposition pressure. Results show that room-temperature grown BST films have potential for device applications.