Plasmon-electron dynamics at the Au/InSe and Y/InSe interfaces designed as dual gigahertz-terahertz filters

In this work, the X-ray diffraction, the Scanning electron microscopy, the energy dispersive X-ray, the Raman, The UV–vis light and the impedance spectral techniques are employed to explore the structural, vibrational, optical and electrical properties of the Au/InSe and Y/InSe thin film interfaces. It was shown that with its amorphous nature of crystallization, the InSe thin films exhibited n-type conductivity due to the 3% excess selenium. For this form of InSe, the only active Raman spectral line is 121 (cm−1). In addition to the design of the energy band diagram, the analysis the dielectric spectra and the optical conductivities were possible in the frequency range of 270–1000 THz. The modeling of the optical conductivities of the Au, Y, Au/InSe and Y/InSe with the help of Lorentz approach for optical conduction, assured that the conduction is dominated by the resonant plasmon-electron interactions at the metals and metals/semiconductors interfaces. It also allowed tabulating the necessary parameters for possible applications in terahertz technology. These parameters are the electron effective masses, the free electron densities, the electron bounded plasmon frequencies, the electron scattering times, the reduced resonant frequencies and the drift mobilities. On the other hand, the impedance spectral analysis of the Y/InSe/Au interfaces in the frequency range of 0.01–1.80 GHz, revealed negative capacitance effect associated with band filter features that exhibit maximum transition line at 1.17 GHz. This value nominates the interface as a member of filter classes in the gigahertz technology.