Thin Films Made Research Articles

Electrochemical Stability and Large Optical Modulation of the V2O5 Thin Films Made by Spray Pyrolysis

Electrochemical Stability and Large Optical Modulation of the V₂O₅ Thin Films Made by Spray Pyrolysis

Effect of Oxygen Pressure on the Magnetic Properties of Yttrium-Iron-Garnet Thin Films Made by Pulsed Laser Deposition

Yttrium-iron-garnet (YIG) thin films were grown on quartz substrates using pulsed laser deposition (PLD) while varying oxygen gas pressure (P O2 ) in the range of 6.5 × 10 -3 mbar to 1 mbar. YIG phase formation and magnetic properties were strongly dependent on P O2 . The YIG thin film grown at 1.7 × 10 -1 mbar shows the best magnetic properties (4π M s ≈ 1650 G, low H C ≈ 2 Oe) and FMR linewidth (ΔH ≈ 60 Oe) compared to films grown at other P O2 . Our results show that it is possible to obtain single-phase YIG films with low H C and ΔH even on quartz substrates by adjusting the P O2 during deposition.

White Luminescence by Up-Conversion from Thin Film Made with Ln3+-Doped NaYF4 Nanoparticles

Growth of hierarchical ZnO nanostructures composed of ZnO nanoneedles have been achieved via simple thermal evaporation process by using metallic zinc powder in the presence of oxygen at low temperature of 460 degrees C on silicon substrate without the use of any kind of metal catalysts or additives. It is confirmed by detailed structural studies that the as-grown hierarchical nanostructures are single crystalline with a wurtzite hexagonal phase and nanoneedles of these structures are grown along the c-axis in the [0001] direction. The Raman-scattering analysis substantiates a wurtzite hexagonal phase with a good crystal quality for the as-grown products. Room-temperature photoluminescence (PL) exhibits a strong UV emission at 380 nm confirming the excellent optical properties of as-synthesized hierarchical structures. A plausible growth mechanism is also proposed to clearly understand the growth process of the synthesized structures.

The Characteristics of Pb(Mg1/3, Nb2/3)O3–PbTiO3 Thin Films Made by Ultrasonic Spraying MOCVD

Thin films of Pb(Mg 1/3 ,Nb 2/3 )O 3 -PbTiO 3 (PMN-PT) were fabricated on Pt/Ti/SiO 2 /Si substrates by ultrasonic spraying MOCVD and their characteristics were investigated. The content of pyrochlore phase in PMN-PT films decreased with the increase of PT content and nearly single perovskite films were obtained at the composition of 80PMN-20PT. The 70PMN-30PT films with perovskite phase showed a typical butterfly type C-V curve which verifies the ferroelectricity and had the relative dielectric constant of about 500 and the resistivity of about 5 × 10 12 Ω · cm.

Effect of Processing Conditions on the Microstructure and Electrical Resistance of Nanocrystalline ITO Thin Films Made by Laser Ablation

Nanocrystalline indium tin oxide (ITO) thin films were deposited on Si/SiO2 substrates by laser ablation from a ceramic target with a composition of 0.9 In2O3 . 0.1 SnO2. Samples were prepared in the pressure range from 10-1 to 5mbar, either in-situ at 500°C or at room temperature and heat-treated in air at 500°C. X-ray diffraction results show that the films are not oriented, except the ones made at high temperature which exhibit strong (400) orientation. AFM pictures show that the grains are round shaped and the sizes are in the range between 50 and 200nm, except for films made in-situ at 10-1mbar which are elongated and faceted. For higher pressures the grains tend to be small and to form agglomerates. The porosity of the films increases with the deposition pressure and the thicknesses reach a maximum of 2.8µm at 1mbar for the films made at room temperature and of 1.2µm at 2mbar for the ones made in-situ; for higher pressures the growth rate drop drastically, as revealed from SEM observations of cross-sections. The electrical resistance increases with the deposition pressure due to the increase in porosity, changing from 3.3k to 38.9M for films deposited at room temperature and from 20 to 265k for the ones made in-situ.

Growth and Characterization of BaBi2Nb2O9 Thin Films Made by RF-Magnetron Sputtering

The RF-magnetron sputtering technique has been used to deposit polycrystalline thin films of layered-structured ferroelectric BaBi2Nb2O9 (BBN). The XRD patterns for the films annealed at 700°C for 1 hour show the presence of the BBN phase as well as the BaNb2O6 secondary phase. A better crystallization of the BBN phase and an inhibition of the secondary phase is obtained with the increase of temperature. The surface of the prepared films was rather dense and smooth with no cracks. The 300 nm thick BBN thin films exhibited a room-temperature dielectric constant of about 779 with a dissipation factor of 0.09 at a frequency of 100 kHz.

Effect of Zr/Ti Ratio on the Properties of PZT Thin Films Made by MOCVD Using Ultrasonic Nebulization

Pb(Zr,Ti)O3 (PZT) films with various Zr/Ti ratios were fabricated on Pt/MgTi2O5/Si substrates by MOCVD using the ultrasonic nebulization and their characteristics were investigated. PZT thin films with various composition deposited at 400°C were annealed in a RTA (Rapid Thermal Annealing) system at 800°C for 30 sec to minimize the loss of the lead and improve electrical properties. The composition ratio of PZT films affected the crystallographic and electrical properties. For the films crystallized by the RTA process, the remanent polarization of PZT film with near MPB (Morphotropic phase boundary) composition was about 15 μC/cm2 at ±5 Voltage in P-E hysteresis loops. Leakage-current density of PZT films was about 1.0 × 10−7 A/cm2 and 7.0 × 10−5 A/cm2 at +5 V and −5 V, respectively.

Effect of Niobium Modifications to PZT (53/47) Thin Films Made by a Sol-Gel Route

Niobium-modified lead zirconate titanate thin films (PNZT) with nominal compositions, Pb(1−0.5x) (Zr0.53 Ti0.47)1−x Nb x O3:x = 0.02–0.07, have been prepared using a diol based sol-gel route. Single-layer (0.5 μm) films were fabricated on platinised silicon substrates by spin-coating. The effect of niobium additions with regard to phase development, microstructure, and ferroelectric and dielectric properties were investigated for different annealing temperatures. For comparison, unmodified PZT films were also prepared. Niobium substitution increased the crystallisation temperatures for perovskite PNZT phase formation. The values of remanent polarisation P r and dielectric constant e r were found to decrease with the introduction of Nb. For example, in films heated at 700°C for 15 min, the P r value of an unmodified PZT film was 31 μC cm−2, compared to 17 μC cm−2 for an x = 0.05 PNZT film, whilst respective relative permittivity values fell from 1190 to 600. The highest Nb concentration film, x = 0.07, did not display any switchable polarisation characteristics, which is consistent with high levels of intermediate pyrochlore phase.

Substrate Influenced Nucleation and Crystallization of LiNbO3 Thin Films Made by Sol-Gel

AbstractLithium niobate films were deposited on amorphous carbon, silicate glass, (0001) sapphire, and (100) silicon by spin or dip coating double metal ethoxide sols. The crystallinity and microstructure of the deposited films were examined by XRD and TEM. Crystallization behavior and resulting microstructure were strongly influenced by the type of substrate. The formation of crystalline LiNbO3 on amorphous carbon was detected at room temperature. Randomly oriented polycrystalline films were obtained on glass at 400°C. Choice of one mole of water per mole of ethoxide generated heteroepitaxial growth of LiNbO3 thin films on (0001) sapphire. Oriented but polycrystalline films were obtained on silicon. The electrical behavior of film on silicon was evaluated in metal-ferroelectric-semiconductor configuration. A dielectric constant of 35 and a dissipation factor of 0.004 was measured at 100 KHz.

Anomalous Grain Growth of Gold Thin Films Made by Evaporation on Low Temperature Substrate

Anomalous Grain Growth of Gold Thin Films Made by Evaporation on Low Temperature Substrate