Ala’eddin A. Saif

AC Conductivity and Dielectric Relaxation Behavior of Sol-gel BaxSr1-xTiO3 Thin Films

BaxSr1-xTi03 sol-gel thin films with x=0.5, 0.7 and 0.8 have been fabricated as AI/BST/Pt capacitor. The AC conductivity and dielectric properties over a frequency rang of 10 Hz and 1 MHz have been studied in order to explore the ion dynamics and relaxation mechanisms in the films. The frequency dependent conductivity plots show three regions of conduction processes. Dielectric results show that ɛ′ at low frequencies increases as Sr content decreases, whereas at high frequencies, it shows opposite variation, which is attributed to the dipole dynamics. The electric modulus plots reveal the relaxation peaks which are not observed in the ɛ″ plots and the contribution of the grains, grain boundaries and electrode to the relaxation mechanisms.

Microstructure Study on Gd-Doped BaTiO3 Sol-Gel Multilayer Thin Films Using AFM for Optoelectronic Applications

Gadolinium doped barium titanate (Gd-BaTiO3) thin films with the molar ratio of 70:30 have been fabricated on SiO2/Si substrates using sol-gel technique. The effect of number of deposited layers on the grain size and surface morphology has been investigated using an atomic force microscope in contact mode. AFM micro-images show that the films have well distributed grains, dense and crack free surface. In general, the results show that the grain size increases from ~170 nm to ~189 nm as the number of deposited layers increase from one to four layers which attributed to the grain growth mechanism during heating and annealing processes. However, the surface of the films is analysed through amplitude parameters to find out that the films surface is smooth with a predominant for peaks and relatively low number of high peaks and low valleys.

X-ray line profile analysis of BaTiO3 thin film prepared by sol-gel deposition

Barium titanate (BaTiO3) thin film was prepared using sol-gel method and spun-coated on SiO2/Si substrate. The phase and crystallinity of the synthesized film were identified using X-ray diffractometer (XRD), which scanned at the range of 20° to 60°. The phase and lattice parameters of the fabricated film were extracted from the recorded XRD patterns using lattice geometry equations. The crystallite size and lattice strain were determined using X-ray line profile analysis (XLPA) with various approaches. The Scherrer equation was applied to the perovskite peaks of the film to explore the size contribution on the peak broadening. Meanwhile, the Williamson-Hall and size-strain plot (SSP) methods were used to review two main independent contributions, i.e. crystallite sizes and lattice strain, on the X-ray line broadening. From the analysis, it is found that Scherrer method gives smallest crystallite size value by ignoring the strain-induced broadening effect. On the other hand, Williamson-Hall and SSP graphs revealed the existence of the lattice strain within the film, which contributes to the broadening in the Bragg peak. The results that analyzed via both techniques show a linear trend with all data points fitted. However, result obtained from SSP method gives better settlement due to the best fit of the data.Barium titanate (BaTiO3) thin film was prepared using sol-gel method and spun-coated on SiO2/Si substrate. The phase and crystallinity of the synthesized film were identified using X-ray diffractometer (XRD), which scanned at the range of 20° to 60°. The phase and lattice parameters of the fabricated film were extracted from the recorded XRD patterns using lattice geometry equations. The crystallite size and lattice strain were determined using X-ray line profile analysis (XLPA) with various approaches. The Scherrer equation was applied to the perovskite peaks of the film to explore the size contribution on the peak broadening. Meanwhile, the Williamson-Hall and size-strain plot (SSP) methods were used to review two main independent contributions, i.e. crystallite sizes and lattice strain, on the X-ray line broadening. From the analysis, it is found that Scherrer method gives smallest crystallite size value by ignoring the strain-induced broadening effect. On the other hand, Williamson-Hall and SSP graphs...

Influence of the Grain Size on the Conduction Mechanism of Barium Strontium Titanate Thin Films

Sol-gel barium strontium titanate ( Ba0.6Sr0.4TiO3) thin films with different grain sizes have been successfully fabricated as metal-insulator-metal (MIM) capacitors. The perovskite structure of the material has been confirmed via X-ray diffraction (XRD). In order to correlate the effect of the grain size to the conduction mechanisms of these films, atomic force microscopy (AFM) results are presented. The grain size shows an important effect on the conduction mechanism for the films. The results show that as the grain size increases, both the impedance and the permittivity of the films decrease, whereas the conductivity shows an inverse variation. The Z* plane for all films shows two regions, corresponding to the bulk mechanism and the distribution of the grain boundaries-electrodes conduction process.M´´ versus frequency plots reveal non-Debye relaxation peaks, which are not able to be observed in the e´´ plots. Alternating current (AC) conductivity versus frequency plots show three regions of conduction processes, i.e. a low-frequency region due to direct current (DC) conduction, a mid-frequency region due to translational hopping motion, and a high-frequency region due to localized hopping and/or reorientational motion.

Substrate effect on structural and humidity sensing of sol-gel derived Er-BaTiO3 thin films

Sol-gel erbium doped barium titanate (Er-BaTiO3) thin films have been coated on SiO2/Si, fused silica, and Pt/Ti/SiO2/Si substrates. The crystallinity and phase of the thin films have been identified using X-ray diffractometer (XRD). The effect of substrate type on the surface morphologies of the films has been investigated using atomic force microscope (AFM). The influence of humidity on the electrical properties of Er-BaTiO3 films has been carried out using semiconductor parameter analyzer (SPA). XRD patterns show that the films are crystallized with perovskite structure. AFM microimages show well-distributed grains, dense and crack-free surface for the films. The film fabricated on fused silica substrate gives the smoothest surface with smallest grain size, whereas the film coated on Pt/Ti/SiO2/Si gives a relatively rough surface with the largest grain size among the other substrates. The resistance values of the Er-BaTiO3 films at different humidity percentages show that a decrement trend with the hum...

Structural and optical study on sol-gel Ba0.7Gd0.3TiO3 thin films for optoelectronics

Ba0.7Gd0.3TiO3 thin films have been fabricated on fused silica by sol-gel spin coating route and annealed at 900 °C to obtained crystallized films. The effects of number of deposited layers on the surface morphology and optical band gap have been studied using atomic force microscopy and ultraviolet-visible spectroscopy, respectively. The films surface analysed through amplitude roughness parameters which show that the grain size and surface roughness are increased as the number of deposited layers increased. The transmittance spectra disclosed the UV absorption property of the BGT thin films at around 350 nm. The estimated optical band gap from Tauc plot is achieved in the range of 4.091 - 4.193 eV and it is found to be reduced as the number of deposited layers increased.Ba0.7Gd0.3TiO3 thin films have been fabricated on fused silica by sol-gel spin coating route and annealed at 900 °C to obtained crystallized films. The effects of number of deposited layers on the surface morphology and optical band gap have been studied using atomic force microscopy and ultraviolet-visible spectroscopy, respectively. The films surface analysed through amplitude roughness parameters which show that the grain size and surface roughness are increased as the number of deposited layers increased. The transmittance spectra disclosed the UV absorption property of the BGT thin films at around 350 nm. The estimated optical band gap from Tauc plot is achieved in the range of 4.091 - 4.193 eV and it is found to be reduced as the number of deposited layers increased.

Sol-gel synthesis and nanostructure study on multilayered Ba0.7Gd0.3TiO3 thin films

Sol-gel synthesized Ba0.7Gd0.3TiO3 thin films have been fabricated on SiO2/Si substrate. The grain size and surface morphology for different number of deposited layers have been investigated using SEM and contact-mode AFM. SEM images show that the grain size increases from 77 nm to 94 nm as the number of deposited layers increases from one to four layers, which attributed to the grain growth mechanism during baking and annealing processes. On the other hand, AFM images show a dense, smooth and crack-free surface. However, the surface roughness shows a decreasing trend as the number of deposited layers increases, which attributed to the distribution behavior of the grain during the layer deposition and baking process.

Effect of Barium-to-Strontium on Leakage Current Mechanism of Sol-Gel BaxSr1-xTiO3 Thin Films

Ferroelectric barium strontium titanate (BaxSr1-xTiO3) thin films with different Ba content have been fabricated as MFM configuration using sol-gel technique. The effect of barium-to-strontium ratio on the leakage current mechanism of BaxSr1-xTiO3 thin films has been investigated. The results show that the leakage current density increases as Ba content increases, which attributed to the grain size effect. The leakage current for the tested films has been studied using log (J) vs log (E) plane, which shows three distinguished linear regions. These regions have been characterized using power law () to find that: the region at low electric fields (E < 20 KV/cm) is controlled by Ohmic conduction and the other two regions (E > 20 KV/cm) are due to space charge limited conduction, which is also confirmed via modified Langmuir-Child law. In addition, it is observed that at high electric fields region (E > 1.29×105 V/m) the films show Schottky emission (SE) and PooleFrenkel (PF) emission mechanisms.