Papers by Alauddin Hossain
RSC Advances
CuxO nanostructured thin films are potentially appealing materials for many applications. The dep... more CuxO nanostructured thin films are potentially appealing materials for many applications. The deposition technique, SILAR, explored in this paper offers many advantages.
Abiotic reduction of 2-line ferrihydrite: effects on adsorbed arsenate, molybdate, and nickel
RSC Advances, 2013
The abiotic reduction of X-ferrihydrite (X-FH, where X = 0, As, Mo, or Ni at various Fe/X molar r... more The abiotic reduction of X-ferrihydrite (X-FH, where X = 0, As, Mo, or Ni at various Fe/X molar ratios) was investigated by reacting Fe(II)(aq) at solution concentrations of 0.5 mM or 10 mM and at target pH values of 8 or 10 (using lime water as a base) for 7 days. Under all reaction conditions tested, the measured pH was always lower than the target; this difference was greatest for As-FH (at up to 5 pH units). The control FH sample behaved as expected and transformed to lepidocrocite (LP) and goethite (GT) phases. For As-FH, the sample containing less As (Fe/As = 32.9) transformed to LP–GT phases but phase transformation in the sample with more As (Fe/As = 4.47) was inhibited. Solution concentrations of As were below the detection limit for the Fe/As 32.9 sample but As release was evident for the Fe/As 4.47 sample. For Mo-FH, phase transformation to LP–GT phases was observed at lower target pH (8) conditions under both reacting Fe(II)(aq) concentrations. At the higher target pH (10) and using 0.5 mM Fe(II)(aq), phase transformation inhibition was observed for Mo-FH varieties that contained both high (Fe/Mo 12.5) and low (Fe/Mo 31.5) concentrations of Mo. This is the first time an element forming an outer-sphere complex on FH (e.g., Mo) has been shown to retard phase transformation; such phenomena are usually observed for metalloids that form inner-sphere complexes with FH (e.g., As). Under all conditions, Mo was released into solution (up to 340 ppm) and under some conditions was then readsorbed by the solid phase. Finally, all Ni-FH samples exhibited phase transformation under the reaction conditions tested; however, magnetite (MG) and a green rust-like phase were observed in addition to the LP–GT phases. Under all reaction conditions, the largest amount of Ni was released into solution on the first day of reaction, after which the amount in solution decreased with time due to its readsorption into the solid phase.
Materials Chemistry and Physics, 2007
Amino-4-(5-bromothiophen-2-yl)-5,6-dihydro-6-methyl-5-oxo-4H-pyrano[3,2c] quinoline-3-carbonitril... more Amino-4-(5-bromothiophen-2-yl)-5,6-dihydro-6-methyl-5-oxo-4H-pyrano[3,2c] quinoline-3-carbonitrile (ABDQC) powder was synthesized and showed thermal stability up to 535 K. ABDQC films were successfully prepared using thermal evaporation. X-ray diffraction showed that the prepared ABDQC powder had a polycrystalline structure, whereas the deposited film had an amorphous structure. The surface morphology of the films was characterized by using a transmission electron microscope. Optical absorption properties of ABDQC films were investigated by spectrophotometric measurements of the transmittance and reflectance in the wavelength range 200-2500 nm. The films were found to have indirect allowed optical band gap of 2.5 eV. Currentvoltage characteristics of Au/ABDQC/p-Si/Al were measured at different temperatures (300-420 K) in which the temperature dependence of the diode parameters has been discussed. Under illumination, the device showed opencircuit voltage and short-circuit current of 0.09 V and 3.26 9 10 À4 A, respectively.
Cu2O nanorods have been deposited on soda-lime glass (SLG) substrates by the modified SILAR techn... more Cu2O nanorods have been deposited on soda-lime glass (SLG) substrates by the modified SILAR technique by varying the concentration of NaCl electrolyte into the pre-cursor complex solution. The structural, electrical, and optical properties of synthesized Cu2O nanorod films have been studied by a variety of characterization tools. Structural analyses by XRD confirmed the polycrystalline Cu2O phase with (111) preferential growth. Raman scattering spectroscopic measurements conducted at room temperature also showed characteristic peaks of the pure Cu2O phase. The surface resistivity of the Cu2O nanorod films decreased from 15,142 to 685 Ω.cm with the addition of NaCl from 0 to 4 mmol, and then exhibited an opposite trend with further addition of NaCl. The optical bandgap of the synthesized Cu2O nanorod films was observed as 1.88~2.36 eV, while the temperature-dependent activation energies of the Cu2O films were measured as about 0.14~0.21 eV. SEM morphologies demonstrated Cu2O nanorod ...
Effect of Solution pH and Post-annealing temperatures on the Optical Bandgap of the Copper Oxide Thin Films Grown by modified SILAR Method
MRS Advances
Cuprous oxide (Cu2O) thin films have been grown on both soda lime glass (SLG) microscope slides a... more Cuprous oxide (Cu2O) thin films have been grown on both soda lime glass (SLG) microscope slides and Fluorine-doped Tin Oxide (FTO) substrates by a modified SILAR technique. The pH level of the bath solution was systematically varied in the range of 4.50 – 7.95 to elucidate their effect on the physical properties of the deposited product. The prepared films showed compact surface morphology composed of spherical grains evident from their SEM images. The XRD measurement showed that the as-deposited films were single phase Cu2O with (111) preferred orientation and this texturing was found to be increasing with increasing pH and annealing temperature. The annealed Cu2O films were found to be stable up to 200 °C and completely converted to cupric oxide (CuO) phases when the temperature reached to 350 °C. The estimated optical bandgaps of the as-grown samples were found in the range of 2.28 – 2.48 eV using UV-Vis-NIR transmission data and showing a bandgap narrowing trend with the decreas...
Optimization of the growth conditions of Cu2O thin films and subsequent fabrication of Cu2O/ZnO heterojunction by m-SILAR method
2020 IEEE International Women in Engineering (WIE) Conference on Electrical and Computer Engineering (WIECON-ECE), 2020
Cuprous oxide (Cu2O) and zinc oxide (ZnO) thin films are the most preferable p-type and n-type ma... more Cuprous oxide (Cu2O) and zinc oxide (ZnO) thin films are the most preferable p-type and n-type materials respectively for preparing all oxide based solar cells. In this study, both Cu2O and ZnO thin films were prepared by modified Successive Ionic Layer Adsorption and Reaction (m-SILAR) method. During the growth of Cu2O phase, the pH conditions were optimized at 7.95 and 5.20 which were then annealed at 350 °C for 1 hour. Both XRD and Raman of unannealed and annealed samples showed peaks for Cu2O and CuO films, respectively. The estimated band gap was in the range 2.07-2.16 eV for Cu2O and 1.43-1.51 eV for CuO thin films. For Cu2O phase, the activation energy was found in the range of 0.004~0.19 and 0.01~0.68 eV at the temperature range 40-90 °C and 100-250 °C , respectively. Finally, diode like I-V characteristic behavior was observed for the m-SILAR grown Cu2O/ZnO heterojunction.
Influence of Substrate, Process Conditions, and Post-Annealing Temperature on the Properties of ZnO Thin Films Grown by SILAR Method
Here we report the effect of substrate, sonication process, and post-annealing on the structural,... more Here we report the effect of substrate, sonication process, and post-annealing on the structural, morphological, and optical properties of ZnO thin films grown in presence of isopropyl alcohol (IPA) at temperature 30 – 65 ℃ by SILAR method on both soda lime glass (SLG) and Cu foil. The X-ray diffraction (XRD) patterns confirmed the preferential growth of ZnO thin films along (002) and (101) plane while grown on SLG and Cu foil substrate respectively. Both XRD and Raman spectra confirmed the ZnO and Cu-oxide phases of the deposited films. Scanning electron microscope (SEM) image of the deposited films shows compact and uniformly distributed grains for samples grown without sonication while using IPA at temperature 50 and 65 ℃. The post-annealing treatment improves the crystallinity of the films, further evident by XRD and UV-VIS-NIR results. The estimated optical bandgaps are in the range of 3.37-3.48 eV for as-made samples. Results revealed that high-quality ZnO thin films could be ...
ACS Omega
Here, we report the effect of the substrate, sonication process, and postannealing on the structu... more Here, we report the effect of the substrate, sonication process, and postannealing on the structural, morphological, and optical properties of ZnO thin films grown in the presence of isopropyl alcohol (IPA) at temperature 30−65°C by the successive ionic layer adsorption and reaction (SILAR) method on both soda lime glass (SLG) and Cu foil. The X-ray diffraction (XRD) patterns confirmed the preferential growth thin films along (002) and (101) planes of the wurtzite ZnO structure when deposited on SLG and Cu foil substrates, respectively. Both XRD and Raman spectra confirmed the ZnO and Cu-oxide phases of the deposited films. The scanning electron microscopy image of the deposited films shows compact and uniformly distributed grains for samples grown without sonication while using IPA at temperatures 50 and 65°C. The postannealing treatment improves the crystallinity of the films, further evident by XRD and transmission and reflection results. The estimated optical band gaps are in the range of 3.37−3.48 eV for the as-grown samples. Our experimental results revealed that high-quality ZnO thin films could be grown without sonication using an IPA dispersant at 50°C, which is much lower than the reported results using the SILAR method. This study suggests that in the presence of IPA, the SLG substrate results in better c-axis-oriented ZnO thin films than that of deionized water, ethylene glycol, and propylene glycol at the optimum temperature of 50°C. Air annealing of the samples grown on Cu foils induced the formation of Cu x O/ZnO junctions, which is evident from the characteristic I−V curve including the structural and optical data.
Cuprous oxide (Cu 2 O) thin films have been grown on both soda lime glass (SLG) microscope slides... more Cuprous oxide (Cu 2 O) thin films have been grown on both soda lime glass (SLG) microscope slides and Fluorine-doped Tin Oxide (FTO) substrates by a modified SILAR technique. The pH level of the bath solution was systematically varied in the range of 4.50-7.95 to elucidate their effect on the physical properties of the deposited product. The prepared films showed compact surface morphology composed of spherical grains evident from their SEM images. The XRD measurement showed that the as-deposited films were single phase Cu 2 O with (111) preferred orientation and this texturing was found to be increasing with increasing pH and annealing temperature. The annealed Cu 2 O films were found to be stable up to 200 0 C and completely converted to cupric oxide (CuO) phases when the temperature reached to 350 0 C. The estimated optical bandgaps of the as-grown samples were found in the range of 2.28-2.48 eV using UV-Vis-NIR transmission data and showing a bandgap narrowing trend with the decreasing level of solution pH. The effect of post-annealing temperatures (75-350 0 C) on the as-deposited films was also studied and found to be crucial to control the optical bandgap (1.44-2.13) eV and electrical properties of the films. The sheet resistance of the as-deposited samples was found to be decreasing from 4120 MΩ/square to 800 MΩ/square while grown
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Papers by Alauddin Hossain