Herein, copper selenide thin films are coated onto transparent lead substrates. Pb/CuSe stacked layers is fabricated by the thermal evaporation technique under a vacuum pressure of 10-5 mbar. They are structurally, morphologically, optically and electrically characterized. Lead substrates enhanced the crystallinity of CuSe through increasing the crystallite sizes, reducing the microstrain and lowering defect densities. In addition, a blue shift in the energy band gap associated with remarkable increase in the value of the high frequency dielectric constant resulted from replacement of glass by Pb substrates. Moreover, significant increase in the optical conductivity in the ultraviolet range of light is observed. Fitting the optical conductivity in accordance with Drude- Lorentz models allowed determining the effect of transparent Pb substrates on the plasmon frequency, scattering time at femtosecond level and drift mobility of CuSe. On the other hand, electrical measurements on the Pb/CuSe/C by imposing an ac signal of low amplitude in the frequency domain of 10-1000 MHz, have shown that the Pb/CuSe can perform as negative capacitance source employable for devices scaling and low power applications.
In this work, copper selenide thin films coated onto glass and transparent lanthanum substrates are studied. The (glass, La)/CuSe thin films which are prepared by the thermal evaporation technique under a vacuum pressure of 10 -5 mbar are structurally, morphologically, optically, dielectrically and electrically characterized. Lanthanum substrates improved the crystallinity by increasing the crystallite size and decreasing both of the microstrains and defect density of copper selenide. La substrates redshifts the energy band gap and doubled the dielectric constant values. In addition, employing Drude-Lorentz approaches for optical conduction to fit the dielectric constant provided information about the effects of La substrates on the drift mobility, plasmon frequency, free carrier density and scattering times at femtosecond level. The drift mobility increased and the plasmon frequency range is modified when La substrates are used. Verifying impedance spectroscopy test in the microwave frequency domain have shown that the La(gate)/CuSe/Ag (source) transistors can be employed as band pass filter suitable for 5G technologies. The microwave cutoff frequency reached ~5.0 GHz at a notch frequency of 2.80 GHz of the La/CuSe/Ag highpass filters.
In this work, copper selenide thin films coated onto glass and transparent lanthanum substrates are studied. The (glass, La)/CuSe thin films which are prepared by the thermal evaporation technique under a vacuum pressure of 10− 5 mbar are structurally, morphologically, optically, dielectrically and electrically characterized. Lanthanum substrates improved the crystallinity by increasing the crystallite size and decreasing both of the microstrains and defect density of copper selenide. La substrates redshifts the energy band gap and doubled the dielectric constant values. In addition, employing Drude-Lorentz approaches for optical conduction to fit the dielectric constant provided information about the effects of La substrates on the drift mobility, plasmon frequency, free carrier density and scattering times at femtosecond level. The drift mobility increased and the plasmon frequency range is modified when La substrates are used. Verifying impedance spectroscopy test in the microwave frequency domain have shown that the La(gate)/CuSe/Ag (source) transistors can be employed as band pass filter suitable for 5G technologies. The microwave cutoff frequency reached ~ 5.0 GHz at a notch frequency of 2.80 GHz of the La/CuSe/Ag highpass filters.
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