Herein, the structural, morphological, optical and electrical properties of CdO stacked layers comprising Si slabs of thickness of 100 nm are investigated. The performance of the stacked layers, which are prepared by the thermal evaporation technique under vacuum pressure of 10-5 mbar, is remarkably enhanced via insertion of Si thin slabs. The presence of Si slabs between the layers of CdO improves the crystallinity and surface morphology, increases the light absorbability in the ultraviolet and visible ranges of light and also increases the dielectric constant, the quality factor, and optical conductivity values. The optical conductivity parameters, which are analyzed in accordance with Drude-Lorentz approach, have shown that the insertion of the Si layers rises the values of the drift mobility of holes in CdO and lowers the free holes concentration. The energy band gap of CdO films is narrowed from 2.20 to 1.27 eV upon insertion of Si slabs. The applicability of the plasmonic CdO/Si/CdO devices as low pass filers in the frequency domain of 0.01-1.80 GHz is verified through impedance spectroscopy measurements.

InSe based heterojunction devices gain importance in optoelectronic applications in NIR range as multipurpose sensors. For this reason, InSe/Sb2Te3 heterojunctions are constructed as NIR sensors by the thermal evaporation technique. The structural, optical, dielectric and photoelectric properties of InSe/Sb2Te3 heterojunctions are explored by X-ray diffraction and ultraviolet-visible light spectrophotometry techniques. The structural analyses revealed the preferred growth of polycrystalline hexagonal Sb2Te3 onto amorphous InSe as a major phase. Optically, the coating of Sb2Te3 onto InSe enhanced the light absorbability of InSe by more than 18 times, redshifts the energy band gap, increased the dielectric constant by ~5 times and increased the optical conductivity by 35 times in the NIR range of light. A conduction and valance band offsets of 0.40 and 0.68 eV are determined for the InSe/Sb2Te3 heterojunction devices. In addition, the Drude-Lorentz fittings of the optical conductivity indicated a remarkable increase in the plasmon frequency values upon depositing of Sb2Te3 onto InSe. The illumination intensity and time dependent photocurrent measurements resulted in an enhancement in the photocurrent values by one order of magnitude. The response time of the devices is sufficiently short to nominate the InSe/Sb2Te3 heterojunction devices as fast responding NIR sensors suitable for optoelectronic applications.

Abstract In this study, the design and characterization of CdO/InSe thin film transistors (TFT) that are grown onto Au substrates are investigated. The devices are also subjected to a vacuum annealing process at 300 oC to enhance the structure and electrical performance. It was observed that the growth of polycrystalline monoclinic In6Se7 phase of InSe is preferred at this annealing temperature when coated onto Au/CdO substrates. Electrically, noisy negative capacitance effect accompanied with resonance-antiresonance phenomena is observed in the capacitance spectra of the as prepared TFT devices. The annealing of the TFT devices reduced the noise in the capacitance, conductance, impedance, and reflection coefficient and return loss spectral responses. The heat treated TFT devices displayed low bandpass, high bandpass and bandstop filter characteristics in the studied frequency domain (0.01-1.80 GHz) indicating the applicability of these devices as radio wave-microwave resonators.