In this work, the application of RF power in stepped mode during the growth process of CdTe films deposited on glass substrates at room temperature and their structural, morphological, and optical properties were studied. The working pressure and deposition time during deposition were 10 mTorr and 120 min, respectively, meanwhile the RF power was gradually varied from 30 W to 40 W. For comparison and reference, CdTe films with 30 W and 40 W (fixed power values) were also deposited, which resulted amorphous. The x-ray diffraction results of the films prepared with stepped RF power were polycrystalline with cubic structure and (111) as preferential orientation. The crystallite size of films changes from 16.6 to 29.2 nm as the rate of the stepped RF power increases. Raman spectra show that intensity of peaks located at 123, 140 and 164 cm-1 increase with the increased rate of stepped RF power, as well as the rms-roughness and grain size values increase from 0.8 nm to 1.6 nm and from 62.8 nm to 92.1 nm, respectively. The UV-Vis spectra show that the bandgap energy of the deposited CdTe films changes from 1.47 to 1.54 eV with the increased rate of stepped RF power. The obtained bandgap energy values of the CdTe films are adequate to be used as absorber material for photovoltaic applications into the ZnO/CdTe and CdS/CdTe solar cells.

Cadmium selenide nanoparticles (NPs-CdSe) were synthesized by colloidal route at room temperature and atmospheric pressure using cadmium chloride (CdCl2·2.5 hydrate) and elemental selenium (Se) as precursors. Sodium borohydride (NaBH4) was used as reducing agent to obtain Se2− ions and an aqueous solution with a NaOH and Penta sodium tripolyphosphate (STPP) was used to protect Cd2+ ions. To remove the by-products generated during the chemical reaction and to promote the precipitation of NPs-CdSe, a cleaning process with an aqueous solution of HCl was performed. The HCl volume was varied from 0.2 to 1.2ml during the cleaning process to study its effects on CdSe synthesis. The crystalline structure was analyzed by inspection of the high-resolution transmission electron microscope (HR-TEM) and X-ray diffraction (XRD). This analysis showed that crystals of CdSe exhibit a face-centered cubic structure (FCC). The calculated crystallite size is 3.5nm and increases to 4.5nm as the HCl volume increases. The morphologies of the products were observed by SEM and TEM techniques. HRTEM images showed that NPs-CdSe synthetized to 0.8ml are composed of a great number of homogeneous and smooth nanospheres which are not appreciable in SEM but are observable in TEM. By contrast, 0.2 and 1.2ml HCl samples are comprised of a great deal of rods of compounds of Se mixed with CdSe spheres nanostructures. This work, which did not require the use of surfactants complexes or specials environment, is considered to have advantages over other works

An electronic system for applying electrical current pulses with fixed time between 10 and 500 μs on metallic films is described. The system is capable to measure changes on the electrical resistance (i.e, temperature) at room temperature and atmospheric pressure, when micropulses are applied on the nano-thickness metallic films deposited on thick substrates. The proposed electronic system is mainly formed by three sections: the micropulses generator section which works with a PIC 16F84A device, the signals processor section (AD712 and LT1210 amplifiers, and an AD734 multiplier/divider), and the data acquisition section integrated by a digital oscilloscope Tektronix model DPO 4050. By applying controlled micropulses on the metallic films and measuring the corresponding changes of the electrical resistance, which are converted at temperature, it is possible to determine the heat capacity of the metallic films at nano-dimensional scale. The proposed electronic system is used to characterize gold thin films deposited on polymeric substrates. Preliminary results determine a heat capacity value of 118 ± 7 nJ/°C for a 100 nm-gold film.

Phthalocyanines represent a significant class of organic semiconductors that have garnered attention for their potential applications in conducting polymers and organic electronics. The unique structural characteristics of phthalocyanines, coupled with the intriguing chemical behavior and variations in bandgap associated with different substitution sites, offer exciting prospects for designing novel application devices. In this study, we have successfully fabricated a heterostructure incorporating dichloro tin (IV) hexa deca fluoro phthalocyanine (F₁₆PcSnCl₂) on both porous silicon (PS) and crystalline silicon (c-Si). The PS substrate was prepared using metal-assisted chemical etching. To explore the optoelectronic applications, we thoroughly characterized the optical, electrical, and morphological properties of the heterostructure. F₁₆PcSnCl₂ exhibits the lowest reflectance within the visible light spectrum, making it highly advantageous for photosensitive applications that necessitate efficient light absorption, diffusion, or scattering. The morphological analysis of the F₁₆PcSnCl₂ film reveals the presence of nanosphere-type structures uniformly distributed on both PS and c-Si substrates. The absorbance spectrum exhibits three distinct bands, which serve as typical indicators of the F₁₆PcSnCl₂ complex. Several hybrid heterostructures were fabricated for electrical characterization, displaying rectifying ohmic behavior and demonstrating a photocurrent effect in the I-V curves. Notably, when the heterostructures were polarized at 1 V, a pronounced response to pulses of white light was observed in the current–time curves. Overall, the integration of organic and inorganic materials in heterostructures holds great promise for innovative applications in optoelectronics.