Selenium oxide thin films are highly transparent optical layers proper for optoelectronic technology. However, SeO₂ films are rarely studied and observed suffering from clustery surface morphology, low light absorbability and low dielectric constant. For this reason herein, in an attempt to enhance its properties, platinum nanosheets (10–50 nm) are used as plasmonic substrates to grow transparent selenium oxide thin films. The films are deposited onto glass and Pt substrates using thermal evaporation technique under a vacuum pressure of 10⁻⁵ mbar. Both films of the glass/SeO₂ and Pt/SeO₂ are characterized by the techniques of x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, optical spectrophotometry and impedance spectroscopy. While no significant effect of Pt nanosheets on the amorphous nature of structure of SeO₂ is observed, remarkable enhancements in the light absorbability by 50 times and in dielectric constant by three times are achieved. In addition, Pt nanosheets form plasmonic interfaces resulting in improving the plasmon frequency, drift mobility and free carrier density of the films. Pt/SeO₂ films showed plasmon frequency larger than 6.0 GHz and free carrier density of 10¹⁸ cm⁻³. Moreover, analysis of the terahertz cutoff frequency and impedance spectra have shown that the Pt/SeO₂ interfaces can also be employed as terahertz receivers and as low pass filters suitable for 5G/6G technologies.

Herein the design of broken gap heterojunction devices made of molybdenum trioxide and zinc phthalocyanine coated onto Al substrates are reported. The devices which are prepared by the thermal evaporation technique under vacuum pressure of 10-5 mbar are observed to exhibit a conduction and valence band offsets of 3.36 and 3.56 eV, respectively. The heterojunction devices are observed to form a subband gap of 0.66 eV between the valence bands edges of p –ZnPc and conduction bands edges of p-MoO3 leading to a p+/n+ heterojunction type. Analysis of the current-voltage characteristics of the devices has shown that it exhibits tunneling diode characteristics with maximum tunneling barriers of width of ∼ 45 nm. The device displayed biasing dependent photosensitivity in response to 850 nm laser lights. In addition to its characteristics as MOS device, when it was imposed with ac signals in the frequency domain of 0.01-1.80 GHz, it displayed resonance-antiresonance phenomena accompanied with negative capacitance effect in the studied range of spectra. The analysis of the alternating current (ac) electrical conductivity has shown that the ac conduction is mostly governed by quantum mechanical tunneling assisted with correlated barriers hopping. The laser light photosensitivity, the negative capacitance effect, the capacitance switching within 100 ns and the bandpass characteristics with notch frequency of 1.24 GHz make the Al/MoO3/ZnPc/Al attractive for use as IR sensors, parasitic capacitance cancellers, fast capacitance switches and microwave bandpass filters.

Herein the fabrication and practical applications of p − MgSe thin films as active p − layer of electronic devices are reported. MgSe films are prepared by a vacuum evaporation technique onto n − Si substrates under a vacuum pressure of 10 ^–5 mbar. The films are morphologically, structurally, electrically and opto-electronically investigated. Having identified the work function of p − MgSe as 6.74 eV, the role of Ag, C, Au and Pt metal contacts on the performance of the n − Si/ p − MgSe (SM) diodes are studied. It is observed that high rectification ratios of ∼10 ⁴ and 10 ² are achieved at an applied voltage of 3.0 V for the Ag/SM/C and Ag/SM/Ag diode structures, respectively. In addition, a current responsivity to visible and infrared light of ∼0.70 A W ⁻¹ is observed for the Ag/SM/Ag channels. The noise equivalent ratios, the external quantum efficiency and the detectivity of the Ag/SM/Ag diodes suit requirements of visible light and infrared communication detectors. Moreover, studies of the capacitance-voltage characteristics showed capacitor characteristics. The depleting of the Ag/SM/Ag capacitors is possible up to 50 MHz. Furthermore, analyzing the capacitance, resistance and cutoff frequency spectra have shown that the Ag/SM/Ag device channels can perform as negative resistance sources with cutoff frequency values that suits 6G technology requirements.