Papers by Keyword: Sputtering

Abstract: Anatase-type TiO₂ films synthesised on quartz glass demonstrated cell adhesion control when illuminated from the backside with a 150 W Xe lamp emitting white light. The UV component was fully absorbed by the TiO₂ film, preventing cell exposure to it. By selectively applying localised light, non-contact control of cell adhesion areas was achieved. If non-toxic films responsive to conventional LED panels could be used, this would enable precise and easy control of cell adhesion areas. The purpose of this study was to synthesise inorganic semiconductor films with a narrower bandgap than TiO₂, responding to visible light from LED, and to investigate their photo-responsive properties. α-Fe₂O₃ films were deposited on borosilicate glass or ITO-coated quartz glass using RF sputtering with the corresponding metallic targets under an Ar or Ar/O₂ mixed atmosphere. XRD analysis showed sharp diffraction peaks, confirming the successful synthesis of the films. The absorption edges of the oxides shifted to longer wavelengths compared to that of TiO₂, corresponding to their bandgap differences. When a tablet device (HUAWEI MediaPad M3 Lite 10wp) displaying a white image was used as a light source, the oxide films showed a noticeable photocurrent. In the photocurrent profile during the on/off cycle of the light, a phenomenon of current flowing in the reverse direction when the light was turned off was observed. Moreover, this current reversal was more pronounced when the grains were fine. This suggests that the grain boundaries acted like a capacitor and induced polarisation behaviour.

Abstract: SiC sputtered and e-beam evaporated layers have been deposited on 4H-SiC substrates. High temperature annealing with two plateaus at 1400°C and 1700°C is performed to recrystallize the layers. The crystallinity was investigated by Raman spectroscopy with laser lines of 785, 405 and 325nm. To determine the electrical conductivity of the layers, electrical measurements are made. Only the electron beam evaporated layers presents a recrystallization close to homoepitaxial quality but, contrary to sputtered layers, they don’t have an electrical conductivity.

Abstract: This paper investigates performance of ZnO/SnO₂ nanorods structure thin film deposited at two different ZnO seed layer (ZnO seed A and ZnO seed B) for humidity sensor application. ZnO seed A and ZnO seed B were deposited using two different method which were sputtering method and spin coating method respectively. ZnO/SnO₂ nanorods structure thin film that has been prepared on ZnO seed A and ZnO seed B using thermal chemical vapor deposition (CVD). The structural properties have been characterized using field emission scanning electron microscopy (FESEM) (JEOL JSM 6701F). Base on the FESEM image the size of ZnO seed A and ZnO seed B were ranging around 75 to 85 nm and 17 to 21 nm respectively. The results analyzed were for ZnO/SnO₂ composite nanorods structure size on ZnO seed A and ZnO seed B were averagely around 18 nm to 29 nm. The sensor properties were characterized by using current-voltage (I-V) measurement (Keithley 2400). ZnO/SnO₂ nanorods structure thin film deposited on ZnO Seed A performed highest sensitivity with 265 ratio compare to ZnO/SnO₂ nanorods structure thin film deposited on ZnO Seed B with 75 ratio of sensitivity.

Abstract: We study the crystal structure of carbon-doped Al-rich MnAl thin films deposited on Si substrates. The effects of carbon content and vacuum heat treatment parameters are studied. It is shown that the carbon content, in combination to heat treatment, allows to tailor structural phase transitions in the films. The main phases detected are Al₂Mn₃, pure Mn, and pure C. As carbon content increases, the amount of Al₂Mn₃ phase decreases and the content of pure crystallized Mn phase increases. In addition, it is shown that as the heat treatment temperature increases – up to 500 °C – the Al₂Mn₃ phase content increases, whereas a pure C phase appears at lower temperatures.

Abstract: In this research study, aluminum Nitride (AlN) thin film co-doped with erbium and ytterbium has been deposited on Si (100) substrate by RF magnetron Sputtering. After deposition, the film was annealed at 1100 °C in ambient conditions. It’s structural properties were investigated X-ray diffraction (XRD). Thin films morphology is studied using SEM, and EDX provides the chemical composition information. The photoluminescence property of deposited film was investigated by FS5 spectrofluorometer. XRD result revealed that the film has grown along the c-axis oriented in hexagonal wurtzite structure. SEM Result shows that the average size of the particle is 100 nm. The up-conversion luminescence showed intense green and red emission peaks at 530 nm, 552 nm, and 665 nm due to the transition of Er (²H_11/2 → ⁴I_15/2, ⁴S_3/2 → ⁴I_15/2, and ⁴F_9/2 → ⁴I_15/2) with excitation of 984 nm. The excitation wavelength with 483 nm photons produces visible luminescence in the green and red region with 557 and 660 nm due to Erbium.

Abstract: Thin Mo films in the thickness range between 1 and 164 nm have been deposited on high-quality quartz and Corning glass substrates by Radio Frequency (RF) magnetron sputtering under high vacuum (base pressure ~ 3 × 10^-7 mbar). The sputtering target was metallic Mo. Subsequent short annealing of Mo at temperatures between about 400 °C - 600 °C in a muffle furnace in air produced MoO₃ thin films. Heating even to 400°C resulted in significant growth of crystal size. Surprisingly, films thinner than about 50 nm could not be heated at higher temperatures due to the evaporation of the oxide. Ultraviolet – visible light absorption spectroscopy experiments were employed for the determination of the optical band gap. The results for direct and indirect allowed transitions are discussed.

Abstract: Genome engineering is a powerful tool that enhances the accelerated innovation in materials development allowing both the discovery and optimization of functionalities based on a wide range of techniques. Thin films engineering is in the forefront of this new approach by allowing the generation of a wide range of compositions in a limited number of experiments and taking advantage out of the possibility to use high-throughput characterization techniques. The paper exemplifies the innovation via compositional spreads generated by magnetron sputtering and the mapping of the material’s manufactured libraries via electric resistivity and interfacial contact resistance measurements.

Abstract: The deposition of Zinc Sulfide (ZnS) thin films is optimized using a radio-frequency (RF) magnetron sputtering technique with variable RF power to minimize deposition steps and lower the fabrication costs. Room temperature as-deposited film growth optimization is conducted by studying their structural, morphological, optical, and electrical properties. The target power and deposition rate were related by a slope of 0.1648 and a linear correlation coefficient (R) of 0.9893. Only one significant peak for the films in the XRD pattern indicated that the films are of a single crystalline structure. All the deposited thin films exhibited a ZB structure. It is observed that the micro-strain ranged from 36.00x10^-3 to 4.14x10^-3, and that of dislocation density ranged from 6.68 to 0.08 Line/cm². The optical energy band gaps of as-deposited ZnS films at different deposition power were found from 3.31 to 3.37 eV. The average transmittance percentage was increasing from 71.63% to 84.29%, above 400 nm wavelength. The films exhibited n-type conductivity with bulk carrier density in the order of 10¹² cm^-3. The carrier concentration and mobility ranged from 2.84x10¹¹ to 3.98x10¹² cm^-3 and 1.06 to 27.68 cm²/Vs, respectively. The minimum and maximum resistivity of 1.01x10⁴ and 2.52´10⁵ Ω-cm were noted for the film deposited at 90 and 60W power, respectively.

Abstract: Transparent conductive oxides are materials combining great transparency with high conductivity. In photovoltaic applications, they are developed under thin layer for the realization of upper electrodes of solar cells. Among transparent oxide materials, Zinc Oxide (ZnO) presents unique properties, starting with its first qualities to be abundant, low-cost and non-toxic oxide. Zinc Oxide thin film was deposited on rectangular glass substrate by magnetron sputtering. After an overview of the properties expected for good transparent conductive materials, the effect of distance from the center of the cell on the morphology of the film was investigated by Atomic Force Microscopy (AFM). The scanning was done on different area of the sample as function of the distance from the central position of the direct sputtering jet. As far as the distance increased, it has been noticed a quasi-linear increase in thickness of the ZnO deposited film and a change in the grain shape from spherical to pyramidal with an increase in the size of the particles. Controlling the sputtering distance allows the control of texture, thus of the Haze factor, the photo-generation of excitons, as well the optical transmission of the TCO layer and finally an improvement in the efficiency of the so-built photovoltaic cells.

Abstract: The effect of various target to substrate distance on the physical properties of sputtered Gd-doped ZnO thin films were investigated. The thin films with three distances between a target to substrate ranged from 12.0, 13.5 and 15.0 cm were deposited by a dual-target sputtering method. All the thin film properties were characterized using x-ray diffraction, atomic force microscope, energy dispersive x-ray analysis and ultra-violet visible spectrophotometer. The sharp and intense peak of (002) was observed for a sample with the target to substrate distance of 13.5 cm which indicated good crystallinity as compared to other samples. Gd incorporations of 3 at% in ZnO films were further confirmed via the energy dispersive x-ray analysis. AFM images revealed that the surface topology Gd-doped ZnO thin film have a smooth and uniform surface. The transmittance was above 90 % and slightly decrease with the increase of target to substrate distance. The bandgap value was static at 3.14 eV for all the 12.0, 13.5 and 15.0 cm of various target to substrate distances.