Papers by Keyword: Growth Temperature

Abstract: Photo-supercapacitor (PSC) is integrated harvesting energy, that a combination of DSSC with a symmetric supercapacitor. A crucial part of the conversion of photon energy by DSSC is a photoanode. The DSSC photoanode used ZnO NR, because it is known as one of the optical semiconductor materials, which has bandgap of 3.37 eV. Due to good cycle stability and high conductivity, the supercapacitor electrode uses activated carbon-carbon black (AC-CB) materials. This study observed the enhance of temperature growth on the structure, morphology, and optical properties of ZnO NR photoanode to improve the photo-supercapacitor's performance. The hydrothermal method has been chosen to grow ZnO NR photoanode at growth temperature of 100, 150, and 200 °C for 4 hours. The structure, morphology, and optical properties of ZnO NR were analyzed by XRD, SEM-EDX, and UV Vis, respectively. The electrical performance of photo-supercapacitor were analyzed by IV data. XRD pattern has identified an increase peak in the hkl (002) of c-axis orientation and SEM data has identified that ZnO NR grows perpendicular to the substrate according to the preferred orientation. The optical properties has identified a shift to a small bandgap (redshift). For the electrical performance, photo-supercapacitor has increased in maximum current (I_max) as the growth temperature increases, and the maximum current is obtained by a growth temperature of 200 °C, which is 14.45 μA.

Abstract: The study highlights the effects of growth temperatures ranging from 500 to 650 °C on the properties of indium nitride (InN) thin films prepared by sol-gel spin coating method followed by nitridation, also, the growth mechanism was studied in depth. The findings revealed that the InN crystal growth was promoted at the growth temperature of 600 °C, by which the crystalline quality of the deposited thin films was improved and the densely packed InN grains were formed. However, thermal decomposition of InN was observed at increasing temperature to 650 °C. Apart from that, the infrared (IR) reflectance measurement shows the presence of transverse and longitudinal-optical phonon modes of wurtzite structure InN. These vibrational modes were found to be slightly shifted from the theoretical values as a result of the incorporation of oxygen contamination in the deposited thin films.

Abstract: Co:TiO₂ (cobalt-doped titanium dioxide) thin films have been deposited on the n-type Si (100) substrate at the temperatures range of 325°C 450°C using MOCVD (metal organic chemical vapor deposition) technique. We investigated the effect of growth temperature on the structural and morphological quality of Co:TiO₂ thin films. The structure of Co:TiO₂ thin films were characterized by XRD while the morphology and the thickness of films were characterized by SEM. The XRD results reveal that all films show the anatase structure and the dominant orientation of anatase phase depends on the growth temperature. The grain size of crystal increases as the growth temperature increases. We also reveal that the growth rate of Co:TiO₂ film has a maximum value at the growth temperature of 400°C.

Abstract: Oxide scales have negative effects on the security and economy of supercritical and ultra-supercritical units.The finite volume method was exploited to simulate oxide scales growth temperature on the inside of superheater tube,then the appropriate time and spatial intervals were selected to calculate oxide scales thickness along the circumferential direction with the correspond growth temperature.At last,the stress response of the oxides was simulated with finite element method.The simulated temperature is closed to the analytical temperature, confirming that the simulation results are credible.The results show that the growth temperature rises fast at the beginning and drops in the circumferential direction,which changes rapidly at the 90°. Oxide scales thickness is thinner and thinner in the circumferential direction and changes fast at approximately 90°.Though the magnitude of circumferential stress and axial stress is different, but the trend same.The simulation results can provides a theoretical basis for the failure research of the oxide scales.

Abstract: A novel and simple approach is reported to fabricate ZnO nanorods. Zinc acetate dihydrate, ethanol and de-ionized water were used to prepare seed layer. Zinc nitrate and hexamethylenetetramine solution were used for growth of ZnO nanorods. The ZnO nanorods were grown at two different temperatures of 90°C and 120°C and annealed at three different temperatures of 300°C, 400°C and 500°C in air atmosphere. Nanorod growth temperature and annealing temperature are varied and the corresponding changes in structural, morphological and optical properties were reported. The structure, orientation, surface morphology and optical properties of the ZnO nanorods were investigated by XRD, SEM & UV studies. The influence of growth and annealing temperatures on structural and optical properties were reported.

Abstract: InAs/GaAs quantum dots structures are grown by meta-organic chemical vapor deposition. The effects of growth temperatures on the structural and optical properties of quantum dots are investigated by the atomic force microscopy and photoluminescence. An areal density of 9.3×109cm2 and a strongly enhanced photoluminescence intensity are obtained at the temperature of 505°C, furthermore, the low and high growth temperature tend to form coalescent islands and decrease the intensity of photoluminescence spectra.

Abstract: The size of quantum dots (QDs), their shape, and ordered arrays have significant impact on electrical and optical properties of the QDs. We synthesized near-infrared-emitting PbSe QDs via an oil phase method in a noncoordinating solvent. Transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy were used to characterize the samples. Sizes of the QDs were accurately controlled from 4.2 nm to 10.2 nm through control of the reaction time as well as the growth temperature. The PL spectra showed strong size dependence, which is large red shift with increasing size of the QDs.

Abstract: Slow positron beam are used to study defect structures in Co doped and undoped ZnO films prepared by Pulsed Laser Deposition (PLD) at 400°C, 600°C, 700°C on c-plane sapphire. Comparing with ZnO samples, Co doped ZnO samples have larger positron effective diffusion length (Leff), which change in different tendencies depending on the growth temperature. Crystal structures of the samples are investigated by X-ray diffraction (XRD) and wurtzite ZnO could be observed in Co doped samples.