The Zinc Oxide and the Quantum dots of ZnO (ZnO-QD´s) in thin solid films were deposited by dropwise method on glass substrates and calcined in air atmosphere at temperatures of 60 °C, 100 °C, 140 °C, 160 °C and 210 °C, respectively. The samples are examined applying the techniques: Scanning Electron Microscopy (SEM), x-Ray Diffraction (XRD), Fourier transforms in the Infrared (FTIR), Photoluminescence (PL), Transmittance (%T), and absorbance (α). Tauc model, the band gap (Eg) energy is evaluated. The electrical measurements of Current-Voltage (I-V), the concentration of charge carriers, mobility and Resistance, are registered by Hall Effect. The morphology of the layers shows a structural configuration with stacked compact plates and flakes-like of crystalline conglomerates with a fibrous appearance. The films show a Wurtzite-type crystalline phase according to the XRD diffractograms. The grain size increased by ~3.6-26.1 nm. The dislocation density (δ) presents a gradual increase with the calcination temperature δ(lines/m2) ~1.57 x 1015-2.22 x 1015. On FT-IR spectroscopy analysis, various vibrational bands are associated with the CO32 ion and by-products generated by the hydrolysis of zinc acetate di-hydrate discussed. The Eg undergoes oscillatory and disorderly shifting towards higher photon energy, caused by faults at crystalline lattice of Eg ~3.7-3.87 eV. In optical analysis, the discontinuity located at UV-Vis region is associated in principle at Zn2+→Zn3+ + e- charge transfer. PL spectra at UV-Vis region records the emission bands with different relative intensity. The asymmetric Gaussian curve is associated with intrinsic defects in the crystal lattice. The deconvolution of the Gaussian curve generates different emission bands assigned to: red (RE) at ~770 nm, blue (BE), green (GE) at ~492-520 nm and yellow (YE) at ~570-600 nm. The study and systematic construction of the Schottky diode is done by placing the corresponding thin film on ITO, then PEDOT: PSS was placed, then the silver contact and finally the p-n junction was identified, obtaining better results than QD's ZnO in the Shottky diode plot.
Because it's physical properties, ZnO is considered a potential semiconductor compound for fabricating electronic and optoelectronic functional devices. In this regard, several growth techniques have been developed in order to meet the requirements of commercial devices based in this material. On the pathway for improving the performance of the current devices, low-dimensional ZnO structures seem a promising alternative. Here, we report the process to obtain a metal-insulator-semiconductor (MIS) structure based on ZnO nanostructures grown on the surface of an anodized aluminum substrate (Al2O3/Al) by chemical routes.
This study presents the preparation of porous silicon (PS) using the photoetching technique. The light source was a laser with a 405 nm wavelength. Hydrofluoric acid, hydrogen peroxide, and ethanol were used in the process. An approach to forming PS in a selected area was also studied, in which a computational control of the laser movement was developed. A laser allows for the formation of PS in short period of time using n-type crystalline silicon (c-Si) as a substrate. Photosynthesized PS shows similar characteristics (physical and chemical) to anodized PS. Raman scattering showed a broadening of the peak centered at 525 cm−1, this behavior is related to the formation of PS. Micro-Fourier transform infrared spectroscopy showed bands related to Si-H wagging and SiH2 bending vibrations, these types of bonds were generated during the porosification process. The morphologic characteristics were defined by scanning electron microscopy (SEM) and revealed that the porous structures depend on the potency of the laser used. The topography of the surface confirms PS formation. SEM analysis demonstrated that pores with diameters of 60 and 300 nm can be obtained. Energy-dispersive x-ray spectroscopy showed an increase in oxygen in the PS due to the oxidation process following photoetching. The x-ray diffraction showed that this type of etching eliminates the induced tension in the c-Si grain edges due to PS formation.
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