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Cd 1−x Zn x Te thin films were prepared on 7059 Corning glass substrates using an rf magnetron sputtering system and CdTe(1−y)+ZnTe(y) targets. The concentration (x) of Zn in the films did not coincide with the relative weight (y) of the ZnTe powder in the compressed targets. Values of x were in the range 0–0.30 as determined from x-ray diffraction patterns. The band gap energy (Eg) of the Cd1−xZnxTe samples was calculated from the photoreflectance spectra measured on the films. The position of the experimental points in the Eg versus x plot show a deviation from the phenomenological quadratic relation Eg=Eg0+ax+bx2 calculated within the virtual crystal approximation (VCA). The depart of the Eg values for higher Zn concentrations from the expected VCA model is probably due to a larger clustering of Zn atoms and/or a percolation phenomena. We obtain fitted values for the parameters a and b within the VCA approach. Comparison with data reported by other authors is made.

We present the fabrication and electrical response of a flexible prototype supercapacitor based on activated carbon electrodes obtained from bamboo (Guadua angustifolia Kunth) as precursor. The supercapacitor prototype was fabricated by using a multilayer configuration method; activated carbon electrodes were impregnated with 0.5 M H2SO4 as electrolyte and filter paper was used as separator. Carbon activation was performed by using NaOH and KOH solutions. Activated carbon electrodes were characterized by adsorption isotherms, cyclic voltammetry, and SEM techniques. Electrical response was found by using charge‐discharge curves. Through adsorption isotherms analysis, we found a surface area of 408 and 309 m2 g−1 for the activated carbon with NaOH and KOH, respectively. From the electrical characterization analysis of the supercapacitor device, we obtained 0.92 F for the maximum capacitance value by using 0.5 V as fixed value in the bias voltage. Also, we proposed an equivalent electrical circuit for the supercapacitor prototype. This capacitance value is comparable with the capacitance values exhibited by rigid commercial supercapacitor, such as Dinacap and capacitor Capattery Gold, among others. Finally, these results suggest that the activated carbon from bamboo can be used in flexible electronic applications.

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In this work we proposed a theoretical expression of the band gap dependence with Zn concentration in Cd1–xnxTe alloys. We used the modified virtual crystal approximation and the tight‐binding parameters, which incorporate compositional disorder as an effective potential. The fitting parameters used were the disorder parameter pc for the alloy and the tight‐binding parameters of each binary compound at room temperature. We found that the theoretical model must include disorder effects in order to describe the bowing of the experimental dependence. The theoretical expression is in good agreement with the quadratic function of the energy gap obtained from the fitting of photoreflectance measurements and from values reported by other authors. The experimental analysis was done on polycrystalline thin films grown over glass substrates by rf sputtering technique.