Narrow Results

In order to improve the photoelectric transformation efficiency of thin-film solar cells, one plausible method was to improve the transparent conductive oxides (TCO) material property. In-doped tin oxide (ITO) was an important TCO material which was used as a front contact layer in thin-film solar cell. Using magnetron sputtering deposition technique, we prepared preferential orientation ITO thin films on quartz substrate. XRD and SEM measurements were used to characterize the crystalline structure and morphology of ITO thin films. The key step was adding a ZnO thin film buffer layer before ITO deposition. ZnO thin film buffer layer increases the nucleation center numbers and results in the (222) preferential orientation growth of ITO thin films.

The semiconductor ZnO has gained great interest in the past decades because of its wide bandgap and large exciton binding energy. Especially, the doping and embedded metal nano-particles methods could improve the conductivity of ZnO thin films, which made it possible to fabricate transparent conducting oxides based on ZnO. In the present study, Al-doped ZnO thin layer was employed to manipulate the electrical and optical properties. The band engineering in ZnO makes it possible to manipulate the absorption, emission, reflection spectral of ZnO via the embedded quantum well layer. The ZnO thin films with excellent performance in electrical conductivity and optical transmittance are promising to be applied in the devices including the lager flat screen, touch panel, portable digital device and smart windows. In the present study, we summarized the recent progress in ZnO with embedded metal nanoparticles and application in TCOs.

In this work, the ZnO thin film, the Al-doped ZnO (AZO) thin film (0.98M ZnO, 0.02M Al) and the (Al,Co) co-doped ZnO thin film (AZO:Co) (0.95M ZnO, 0.02M Al, 0.03M Co) were deposited on the glass substrate by the Sol–Gel method. We fabricated a sample of the ZnO thin film, a sample of the AZO thin film and three samples of AZO:Co thin films. The spin-coating was used to deposit thin film on the glass substrate. The ZnO and the AZO thin films were annealed at 450${}^{\circ }$C while three samples of the AZO:Co thin films were annealed at 300${}^{\circ }$C, 450${}^{\circ }$C and 600${}^{\circ }$C in air for 60 min, respectively. In order to prepare three samples of the AZO:Co thin films, we deposited the (Al,Co) co-doped ZnO on the glass substrate for 20 s then all samples were per-heated at 80${}^{\circ }$C for 10 min. we repeated this deposition process five times for each sample. Finally, three samples were annealed at 300${}^{\circ }$C, 450${}^{\circ }$C and 600${}^{\circ }$C in air for 60 min, respectively. The procedure to prepare of the ZnO and AZO thin films was like the AZO:Co thin films except that the annealing temperature was 450${}^{\circ }$C. The structural and optical properties of the thin films were investigated by X-ray diffraction technique, UV-Vis spectrophotometer and Field Emission Scanning Electron Microscopy (FESEM). Results indicated that (Al,Co) co-doping in the ZnO thin film improve the optical transmission while changes in the lattice structure is small with respect to the AZO thin film. Also, the AZO:Co thin film which was annealed at 450${}^{\circ }$C exhibited simultaneously the high thickness and high optical transmission.

Nanostructured Al-doped Zinc oxide (ZnO) thin films were deposited on glass substrate by chemical bath deposition (CBD) using aqueous zinc nitrate solution and subjected for different characterizations. Effect of Al${}^{3+}$ substitution on the properties of ZnO annealed at 400${}^{\circ }$C was studied by XRD and UV-Vis for structural studies, SEM and TEM for surface morphology and DC four probe resistivity measurements for electrical properties. Al${}^{3+}$ substitution does not influence the morphology and well-known peaks related to wurtzite structure of ZnO. Electron microscopy (SEM and TEM) confirms rod shaped Al-doped ZnO nanocrystals with average width of 50nm. The optical band gap determined by UV–Visible spectroscopy was found to be in the range 3.37eV to 3.44eV. An EPR spectrum of AZO reveals peak at $g=1.96$ is due to shallow donors Zn interstitial. The DC electrical resistivity measurements of Al-doped ZnO show a minimum resistivity of $3.77\times 10^{-2}\mathrm{\Omega }$-cm. Therefore, these samples have potential use in n-type window layer in optoelectronic devices, organic solar cells, photonic crystals, photo-detectors, light emitting diodes (LEDs), gas sensors and chemical sensors.