ITO/MgSe interfaces designed as gigahertz/terahertz filters

Abstract

Herein a new class of MgSe gigahertz/terahertz band filters operatives in the frequency domain of 1.0 GHz-1.86 THz is fabricated and experimentally tested. MgSe band filters are coated onto glass and indium tin oxide (ITO) substrates by the thermal evaporation technique under a vacuum pressure of 10-5 mbar. Thin films of MgSe are structurally, morphologically, compositionally, optically and electrically characterized. It is observed that ITO substrates induce the growth of monophasic of MgSe, enhances the crystallinity of the films and blueshifts the energy band gaps of MgSe. Practical applications were verified by impedance spectroscopy technique through imposing an ac signal of driving frequency in the domain of 10.0 MHz-1.8 GHz between the terminals of ITO/MgSe/Au (IMA) devices. It is observed that the IMA devices exhibit negative capacitance effect. Analysis of the cutoff frequency spectra has shown that IMA devices can reveal wide range of tunability in the gigahertz frequency domain. In addition, the cutoff frequency spectra show values reaching ~1.86 THz for signals of driving frequencies of ~1.0 GHz. Evaluation of the magnitude of the reflection coefficient spectra and return loss spectra for these devices show that the IMA devices can perform as bandstop filters with return loss values exceeding 20 dB at 1.0 GHz. The features of the ITO/MgSe/Au devices are appropriate for the 5G/6G technology needs indicating that the device can be employed in communication technology and other gigahertz/terahertz applications.

Formation and Characterization of MgSe Alloys by Pulsed Laser Welding Technique

“…To understand whether the resulting structure of the pressed pellets is related to MgSe crystals or not, diffraction angles of patterns of cubic MgSe crystals are given on the right side of Table 2. [ 5,6 ] The observed diffraction patterns are centered at diffraction angles (2θ) different from those of MgSe compound, Mg, and Se. We attempted to explore the observed crystal structure using the “TREOR 92” software packages.…”

“…On the other hand, the structural parameters are calculated by benefiting from the maximum peak width at full wave half maximum to estimate the peak boarding (β). Namely, the crystallite sizes ($$D = \frac{{0.94\lambda }}{{\beta \;{\rm{cos}}\theta }}$$ [ 6,7 ] ) and the strain ($$\varepsilon = \frac{\beta }{{4\,\tan \theta }}$$ [ 6,7 ] ) in the studied samples were calculated and listed in Table 1. It is clear from the table that the largest crystallite size and least strain are obtained for PLW‐5 and PLW‐50‐1 samples; however, because PLW‐50‐1 samples are composed of 81.52 at% Mg we shall consider the PLW‐5 samples as ideal and optimal samples having a stoichiometric composition, large crystallite sizes, and least strains.…”

“…Examples of these materials are Mg x Cd 1‐ x Se alloys [ 4 ] and MgSe thin films. [ 5,6 ] The aforementioned materials have been found to be suitable for the fabrication of multifunctional devices, such as broadband photodetectors, microwave resonators, and current amplifiers. [ 5,6 ]…”

Iron Selenide Nanowire Bundles for Microwave Communication Technology

“…[ 32 ] The parameters obtained for the FF and FAF bandstop filters are compatible with those reported in the literature data for integrated waveguide filters [ 33 ] and with MgSe‐based gigahertz/terahertz filters. [ 34 ]…”

“…[32] The parameters obtained for the FF and FAF bandstop filters are compatible with those reported in the literature data for integrated waveguide filters [33] and with MgSe-based gigahertz/terahertz filters. [34] It is worth reminding that the critical frequency being 0.87 GHz appears in all the measured spectra including that of impedance, magnitude of reflection coefficient (S 11 ), return loss, and standing wave ratios because all these parameters are related to the impedance value. The return loss and VSWR depend on S 11 parameter through the relations L r ¼ 20log 1 S 11 , and VSWR ¼ 1þjS 11 j 1ÀjS 11 j , respectively.…”