A. K. Shafura

Study on doping effect of Sn doped ZnO thin films for gas sensing application

Tin doped ZnO (Sn:ZnO) thin films were deposited onto glass substrate using sol-gel spin coating method. The doping concentrations of thin films were varied from 1.0 - 5.0 at. % Tin. The optical and electrical properties of Sn doped ZnO thin films were investigated. The electrical properties were analyzed using I-V measurement (CEP 2400). The optical properties were characterized by ultraviolet visible (UV-VIS-NIR) spectrophotometer. Gold (Au) was used as a metal contact using electron beam thermal evaporator (ULVAC). The electrical properties show that the Sn:ZnO thin films exhibit Ohmic behavior with Au metal contact. The highest resistivity of Sn doped ZnO thin films found to be 3.17 × 103 Ωcm. And then, the conductivity of the thin films found to be 1.88 × 10-4 Scm-1 for 2.0 at.% doping concentration. The highest porosity of Tin doped ZnO thin film was found 47% at 3.0 at. % Tin. The highest gas response was found 2.53 in the concentration of Nitrogen gas with flowrate 220mL/min at room temperature. The effect of Tin doping concentration of the ZnO thin films for gas sensing application at room temperature will be extensively discussed in this paper.

Nanostructured Al-doped ZnO-based gas sensor prepared using sol-gel spin-coating method

Nanostructured Aluminium (Al) doped zinc oxide (ZnO) was prepared using sol-gel spin-coating method. These films were tested under different exposure of oxygen flow rates at room temperature with bias voltage applied at 5 V. The structural properties were characterized using Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FESEM). The fesem image revealed the surface morphology of nanostructured ZnO. The diameters size of nanostructured Al-doped ZnO thin film was observed in range of 16-46 nm. These thin films were tested for oxygen-sensing characteristic by varying the gas flow rates at room temperature. The nanostructured Al-doped ZnO-based gas sensor exhibited good sensitivity at low flow rates of oxygen exposure.

Effect of TiO2 thickness on nanocomposited aligned ZnO nanorod/TiO2 for dye-sensitized solar cells

The TiO2 films were deposited on glass substrate at different thicknesses with different deposition frequencies (1, 2, 3 and 4 times) using spin coating technique and their structural properties were investigated. Subsequently, the nanocomposited aligned ZnO nanorods and TiO2 were formed by deposited the TiO2 on top of aligned ZnO Nanorod on ITO-coated glass at different thicknesses using the same method of TiO2 deposited on glass substrate. The nanocomposited aligned ZnO nanorod/TiO2 were coated with different thicknesses of 900µm, 1815µm, 2710µm, 3620µm and ZnO without TiO2. The dye-sensitized solar cells were fabricated from the nanocomposited aligned ZnO nanorod/TiO2 with thickness of 900µm, 1815µm, 2710µm and 3620µm and ZnO without TiO2 and their photovoltaic properties of the DSSCs were investigated. From the solar simulator measurement the solar energy conversion efficiency (η) of 2.543% under AM 1.5 was obtained for the ZnO nanorod/TiO2 photoanode-2710µm Dye-Sensitized solar cell.

Dye-sensitized solar cell using aligned ZnO nanorod grown on SZO films at different solution molarities

In this work, the aligned ZnO Nanorod were grown on ITO-coated glass substrates with Sn-doped ZnO films as a seed layer at different zinc acetate solution molarities of 0.05M, 0.04M, 0.03M and 0.02M by Sol gel immersion ultrasonic assisted. The aligned ZnO nanorods grown at different solution molarities had different of diameter and interspaces between nanorod. The ZnO nanorod grown at 0.03M Zinc acetate exhibits high surface area, whereby bigger interspaces between nanorod and had smaller of nanorod diameter. The nanorod grown at 0.05M had bigger of nanorod diameter and slightly lower of surface area as compared to nanorod grown at 0.03M. Meanwhile, the nanorod grown at 0.02M shows a scattered of nanorod growth with low surface area and lesser density. From the solar simulator measurement the solar energy conversion efficiency (η) of 0.989% under AM 1.5 was obtained for 0.03M aligned ZnO nanorod photoanode DSSC, which higher than other ZnO nanorod photoanode. The improvement which was due to higher surface area of smaller diameter nanorod that had bigger interspaces between nanorod for better dye absorption.

Electrical and structural properties of nanotetrapod zinc oxide thin films prepared with different deposition temperature

Nanotetrapod zinc oxide (ZnO) thin films have been deposited by thermal chemical vapor deposition (TCVD) technique. The films were deposited at 700°C and 800°C to study the temperature effect of physical properties of the nanotetrapod ZnO thin films. From XRD result shows the highest peak can observed from sample 700°C at (002) orientation. It was found that the size of nanotetrapod increased with increased of deposition temperature. The energy dispersive X-ray spectrometer (EDX) spectrum shows that the grown product contains zinc and oxygen only. At 800°C show the minimum of resistivity for the thin film which is 1.10 ohm. cm. Photoluminescence measurement shows a sharp peak ultraviolet emission at 380 nm and high intensity visible peak at 700°C because of defect due to oxygen vacancy and crystallization of ZnO nanotetrapod.

Structural properties of ZnO nano-template layer by spin coating method

Zinc oxide (ZnO) nano-template layer was prepared using spin coating method. The coating layer was varied from 1 to 9 layers in this study. The surface morphology was observed by field emission scanning microscopy (FESEM). Meanwhile, the roughness and total grain boundary were characterised by atomic force microscopy (AFM). The thickness was increased from 90-310 nm, when the coating layer was increased. The grain size was observed below 50 nm. The surface roughness and its total grain boundary was increased and decreased, respectively.Zinc oxide (ZnO) nano-template layer was prepared using spin coating method. The coating layer was varied from 1 to 9 layers in this study. The surface morphology was observed by field emission scanning microscopy (FESEM). Meanwhile, the roughness and total grain boundary were characterised by atomic force microscopy (AFM). The thickness was increased from 90-310 nm, when the coating layer was increased. The grain size was observed below 50 nm. The surface roughness and its total grain boundary was increased and decreased, respectively.

Structural and electrical properties of nanostructured ZnO

Nanostructured zinc oxide (ZnO) thin film was deposited using immersion method. The molarity was varied in range of 0.02 to 0.10 M in this study. The surface morphology was observed by field emission scanning microscopy (FESEM). Meanwhile, the roughness were characterised by atomic force microscopy (AFM). The current-voltage (I-V) measurement was done to determine its electrical properties. Flake-like morphology was found to increase the electrical properties of nanostructured ZnO thin film. The uniformity was increased when the molarity was increased.Nanostructured zinc oxide (ZnO) thin film was deposited using immersion method. The molarity was varied in range of 0.02 to 0.10 M in this study. The surface morphology was observed by field emission scanning microscopy (FESEM). Meanwhile, the roughness were characterised by atomic force microscopy (AFM). The current-voltage (I-V) measurement was done to determine its electrical properties. Flake-like morphology was found to increase the electrical properties of nanostructured ZnO thin film. The uniformity was increased when the molarity was increased.

Raman spectra boron doped amorphous carbon thin film deposited by bias assisted-CVD

Boron doped amorphous carbon thin film carbon was deposited at 200°C-350°C by bias assisted-CVD using palm oil as a precursor material. The structural boron doped amorphous carbon films were discussed by Raman analysis through the evolution of D and G bands. The spectral evolution observed showed the increase of upward shift of D and G peaks as substrate deposition temperatures increased. These structural changes were further correlated with optical gap and the results obtained are discussed and compared. The estimated optical band gap is found to be 1.9 to 2.05 eV and conductivity is to be in the range of 10−5 Scm−1 to 10−4 Scm−1. The decrease of optical band gap is associated to conductivity increased which change the characteristic parameters of Raman spectra including the position of G peak, full width at half maximum of G peak, and ID/IG.Boron doped amorphous carbon thin film carbon was deposited at 200°C-350°C by bias assisted-CVD using palm oil as a precursor material. The structural boron doped amorphous carbon films were discussed by Raman analysis through the evolution of D and G bands. The spectral evolution observed showed the increase of upward shift of D and G peaks as substrate deposition temperatures increased. These structural changes were further correlated with optical gap and the results obtained are discussed and compared. The estimated optical band gap is found to be 1.9 to 2.05 eV and conductivity is to be in the range of 10−5 Scm−1 to 10−4 Scm−1. The decrease of optical band gap is associated to conductivity increased which change the characteristic parameters of Raman spectra including the position of G peak, full width at half maximum of G peak, and ID/IG.

Effect of Nb-doped TiO2 on nanocomposited aligned ZnO nanorod/TiO2: Nb for dye-sensitized solar cells

The Nb-doped TiO2 films were deposited on glass substrate at different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively and their electrical and structural properties were investigated. Subsequently, the Nb-doped TiO2 films were deposited on top of aligned ZnO Nanorod on ITO glass substrates using spin coating technique. The nanocomposited aligned ZnO nanorod/Nb-doped TiO2 (TiO2:Nb) were coated with different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively. The Dye-sensitized solar cells were fabricated from the nanocomposited aligned ZnO nanorod/TiO2:Nb photoanodes and their effects on the performance of the DSSCs were investigated. From the solar simulator measurement of DSSC the solar energy conversion efficiency (η) of 5.376% under AM 1.5 was obtained for the ZnO nanorod/TiO2:Nb-5at.%.

Drying temperature effects on electrical and optical properties of poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) thin film

Temperature effects on electrical and optical properties of a representative semiconducting polymer, poly[2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV), has recently attracted much attention. The MEH-PPV thin films were deposited at different drying temperature (anneal temperature) using spin-coating technique. The spin coating technique was used to produce uniform film onto large area. The MEH-PPV was dissolved in toluene solution to exhibits different optical and electrical properties. The absorption coefficient and bandgap was measured using UV-Visible-NIR (UV-VIS-NIR). The bandgap of MEH-PPV was effect by the thickness of thin films. For electrical properties, two-point probe was used to characterize the current-voltage measurement. The current-voltage measurement shows that the MEH-PPV thin films become more conductive at high temperature. This study will provide better performance and suitable for optoelectronic device especially OLEDs applications.