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Cost-Effective Optimization of Sizing and Charging Profiles for PHEV Parking Lots in Smart Microgrids Using Harmony Search Algorithm
(Institute of Electrical and Electronics Engineers Inc., 2025) Kamarposhti, Mehrdad Ahmadi; Shokouhandeh, Hassan; Ahmed, Emad M.; Zaki, Zaki A.; Çolak, İlhami; Barhoumi, El Manaa; Eguchi, Kei
This paper presents an optimization approach for managing the charging and discharging of electric vehicles (EVs) in parking lots using the Harmony Search (HS) and Differential Evolution (DE) algorithms. The study is conducted on a standard IEEE 33-bus grid considering three EV penetration levels: 11.3%, 35%, and 45%. The objective is to minimize operational costs while improving grid performance. Simulation results indicate that increasing EV penetration slightly raises overall expenses due to the higher cost of vehicle charging compared to the revenue from discharging. However, EV participation significantly reduces ohmic losses and improves the grid load profile. The proposed HS algorithm outperforms the DE algorithm by achieving lower microgrid costs and better convergence efficiency. Specifically, HS reduces energy losses by up to 40%, demonstrating its effectiveness in optimizing energy management for microgrids with high EV integration. © 2013 IEEE.
Antenna Selection With Beam Squint Compensation for Integrated Sensing and Communications
(Institute of Electrical and Electronics Engineers Inc., 2024) Elbir, Ahmet Mete; Abdallah, Asmaa; Çelik, Abdülkadir; Eltawil, Ahmed M.
Next-generation wireless networks strive for higher communication rates, ultra-low latency, seamless connectivity, and high-resolution sensing capabilities. To meet these demands, terahertz (THz) band signal processing is envisioned as a key technology offering wide bandwidth and sub-millimeter wavelength. Furthermore, THz integrated sensing and communications (ISAC) paradigm has emerged to jointly access the spectrum and reduce the hardware costs through a unified platform. To address the challenges in THz propagation, THz-ISAC systems employ extremely large antenna arrays to improve the beamforming gain for communications with high data rates and sensing with high resolution. However, the cost and power consumption of implementing fully digital beamformers are prohibitive. While hybrid analog/digital beamforming can be a potential solution, the use of subcarrier-independent analog beamformers leads to the beam-squint phenomenon where different subcarriers observe distinct directions because of adopting the same analog beamformer across all subcarriers. In this paper, we develop a sparse array architecture for THz-ISAC with hybrid beamforming to provide a cost-effective solution. We analyze the antenna selection problem under beam-squint influence and introduce a manifold optimization approach for hybrid beamforming design. To reduce computational and memory costs, we propose novel algorithms leveraging grouped subarrays, quantized performance metrics, and sequential optimization. These approaches yield a significant reduction in the number of possible subarray configurations, which enables us to devise a neural network with classification model to accurately perform antenna selection. Numerical simulations show that the proposed approach exhibits up to 95% lower complexity for large antenna arrays while maintaining satisfactory communications with approximately 6% loss in the achievable rate. © 2024 IEEE.
Backstepping control of multilevel modified SVM inverter in variable speed DFIG-based dual-rotor wind power system
(SAGE Publications Ltd, 2025) Benbouhenni, Habib; Çolak, İlhami; Bizon, Nicu
The backstepping control (BC) scheme has been successfully used in a variety of high-effectiveness industrial AC drives. This study presents the application of the BC technique based on multilevel modified space vector modulation (BC-MSVM) to get better the energy performance of a dual-rotor wind turbine system (DRWT). Two techniques are suggested to command the stator power of a doubly-fed induction generator (DFIG) driven by a DRWT. This work addresses the problems of the DRWT-based energy production system, such as stream fineness, power overshoot, and torque ripples. The use of a multilevel inverter in BC-MSVM led to an enhancement in the competence of the multilevel BC-MSVM technique and the system as a whole, and this is proven by the results performed using MATLAB software on a 1500 kW DFIG-DRWT. The use of a seven-level inverter led to a minimization in the rates of overshoot, ripples, steady-state error, and response time of active power by 26.66%, 53.84%, 2.09%, and 9.09%, respectively. Regarding the reactive power, the ratios were estimated at 18.12%, 34%, 25%, and 1.41%, respectively. These ratios prove that using a higher-level inverter significantly improves the voltage quality and characteristics of the DFIG-DRWT. © The Author(s) 2024.
Digital Marketing Strategies for Smart Grids: Utilizing Online Platforms to Drive Awareness and Adoption
(16.03.2025) Senyapar, Hafize Nurgul Durmus; Colak, Ilhami; Bayindir, Ramazan
This study investigates the multifaceted role of digital marketing strategies in driving the awareness, acceptance, and adoption of Smart Grid (SG) technologies. The research uses a qualitative exploratory approach to analyze how various online platforms—including social media, multimedia content, email marketing, and paid advertising—can effectively engage diverse audience segments, such as consumers, businesses, utility companies, and policymakers. The findings underscore the importance of personalized, data-driven approaches in enhancing public understanding of SG technologies while emphasizing community engagement and trust-building among stakeholders. The study highlights how sophisticated digital marketing tactics—ranging from engaging videos, podcasts, and infographics to targeted paid advertising—simplify complex SG concepts and increase SG solutions’ visibility and perceived value. Emerging trends, such as influencer marketing and advanced analytics, are critical drivers of future digital marketing efforts in the energy sector. This research provides practical insights for energy companies, policymakers, and marketers, underscoring the potential of digital marketing as a catalyst for accelerating SG adoption, contributing to improved energy efficiency, and fostering a more sustainable energy future
DTC-SVM Control for WECS Based on PMSG Using the Super-Twisting Algorithm
(IEEE, 02.10.2024) Elbar, Chaima Yasmine; Belkacem, Sebti; Colak, Ilhami; Dendouga, Abdelhakim; Farida, Mazouz; Chikhi, Abdesselem
In this research, we suggest a control scheme that incorporates the advantages of SOSMC and SVM-based DTC to boost the efficiency of Wind Energy Conversion Systems (WECS), which utilize PMSG. SOSMC can be used to improve PMSG control in variable renewable energy environments with robustness against uncertainties and disturbances. By incorporating Space Vector Modulation based Direct Torque Control, you can effectively control the generator's flux and torque, ensuring high efficiency and lower harmonic content in the output waveform. The suggested control technique was validated by computer simulations using the MATLAB/Simulink programme.
Effects of ZnPc substrates on the electro-optical properties of MgSe thin films and the applications of Al/ZnPc/MgSe/(Ag, C, Au) hybrid devices as resonant negative capacitance sources
(Springer, 2024) Qasrawi, Atef Fayez
Herein, polycrystalline magnesium selenide (MgSe) thin films are deposited onto glass and monoclinic-structured zinc phthalocyanine (ZnPc) thin film substrates under high vacuum pressure using the thermal evaporation technique. ZnPc substrates improved the crystallinity of the MgSe films and decreased the stacking faults percentages and defect concentration by 31.57 and 52.49%, respectively. MgSe films deposited onto ZnPc substrates exhibited a notable increase of up to 32% in light absorption within the visible spectrum, while maintaining the energy band gap value of MgSe without significant alteration. In addition, as both the substrate and the epilayer exhibited p-type conductivity, an isotype heterojunction device structure is formed at the ZnPc/MgSe interfaces. The valence and conduction band offsets for this interface are 0.81 and 1.16 eV, respectively. On the other hand, re-fabrication of the ZnPc/MgSe heterojunctions onto Al thin film substrates and forming three Ag/MgSe, C/MgSe, and Au/MgSe Schottky channels on the epilayer surface allowed wide control of the negative capacitance effect and the resonance-antiresonance (RA) peaks in the capacitance spectra of the Al/ZnPc/MgSe/(Ag, C, Au) hybrid devices. These two important RA and NC features of the device can also be engineered by altering the DC biasing of the device. Moreover, Lorentz model analyses on the capacitance spectra showed an increased density of oscillators and increased scattering time constant with decreasing built-in potential at the metal/MgSe interfaces. The features of the hybrid devices presented make the device promising for microwave and electro-optical applications. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.
Counterfactuals in fuzzy relational models
(Springer Nature, 2024) Al-Hmouz, Rami; Pedrycz, Witold; Ammari, Ahmed
Given the pressing need for explainability in Machine Learning systems, the studies on counterfactual explanations have gained significant interest. This research delves into this timely problem cast in a unique context of relational systems described by fuzzy relational equations. We develop a comprehensive solution to the counterfactual problems encountered in this setting, which is a novel contribution to the field. An underlying optimization problem is formulated, and its gradient-based solution is constructed. We demonstrate that the non-uniqueness of the derived solution is conveniently formalized and quantified by admitting a result coming in the form of information granules of a higher type, namely type-2 or interval-valued fuzzy set. The construction of the solution in this format is realized by invoking the principle of justifiable granularity, another innovative aspect of our research. We also discuss ways of designing fuzzy relations and elaborate on methods of carrying out counterfactual explanations in rule-based models. Illustrative examples are included to present the performance of the method and interpret the obtained results. © The Author(s) 2024.
Compact ultra-wide band two element vivaldi non-uniform slot MIMO antenna for body-centric applications
(Elsevier B.V., 2024) Saleh, Sahar; Saeidi, Tale; Timmons, Nick; Alali, Bader; Razzaz, Faroq; Althuwayb, Ayman A.
This work presents a novel compact two-port Vivaldi Non-uniform Slot MIMO Antenna (VNSMA) to overcome the challenges of traditional ultra-wideband (UWB) antennas, such as large size, limited bandwidth (BW), high mutual coupling, and suboptimal performance in wearable devices. Designed based on Vivaldi non-uniform slot profile antenna (VNSPA) theory, this antenna offers superior performance metrics and significantly advances wearable antenna technology. The novelty of this work is investigating different positions for the two compact UWB Vivaldi nonuniform Antennas (VNSAs) to get better performance with smaller sizes, wider impedance matching BW, and lower mutual coupling (MC) where side by side at an angle of 180ᵒ is determined to be the best configuration. Detailed parametric studies were performed on this configuration for better performance, where the MC was further reduced by etching the ground plane with a vertical slot between the two antennas and L slots around the Microstrip to Slot (M/S) transition, respectively. Furthermore, BW and gain enhancements were obtained by etching exponential tapered and triangular slots at its two edges. Using the Finite Integration Technique (FIT), Computer Simulation Technology (CST) software is used for the simulations in this work. The VNSMA is tested on a CST Gustav human phantom and gives excellent results with low specific absorption rate (SAR) values at several UWB frequencies. The proposed VNSMA provides good, measured outcomes of S11 < −11.08 dB with wide BW of 12.5 GHz (2.33–14.83 GHz) covering high isolation of −23 dB (for most of frequency band), moderate-high gain of 5.89 dBi, radiation efficiency of 66–90 %, low Envelope Correlation Coefficient (ECC) of 0.002 and high diversity gain (DG) of 9.99 dBi, stable radiation patterns, and average group delay of 1.2 ns. This innovative design, which optimizes antenna positioning and incorporates ground plane modifications, achieves remarkable improvements in BW, which covers multiple bands, including WLAN (2.4–2.485 GHz), X-band (8–12 GHz), and part of Ku band (12–18 GHz). The findings demonstrate the antenna's potential for various high-resolution microwave imaging applications, particularly in medical diagnostics like breast and brain cancer detection, showcasing its impact in wearable technology and healthcare. © 2024 The Authors
Terahertz-Band Integrated Sensing and Communications: Challenges and Opportunities
(Institute of Electrical and Electronics Engineers Inc., 2024) Elbir, Ahmet Mete; Mishra, Kumar Vijay; Chatzinotas, Symeon; Bennis, Mehdi
The sixth generation (6G) wireless networks aim to achieve ultra-high data transmission rates, very low latency, and enhanced energy-efficiency. To this end, terahertz (THz) band is one of the key enablers of 6G to meet such requirements. The THz-band systems are also quickly emerging as high-resolution sensing devices because of their ultra-wide bandwidth and very narrow beamwidth. As a means to efficiently utilize spectrum and thereby save cost and power, THz integrated sensing and communications (ISAC) paradigm envisages a single integrated hardware platform with a common signaling mechanism. However, ISAC at THz-band entails several design challenges, such as beam split, range-dependent bandwidth, near-field beamforming, and distinct channel model. This article examines the technologies that have the potential to bring forth ISAC and THz transmission together. In particular, it provides an overview of antenna and array design, hybrid beamforming, integration with reflecting surfaces, and data-driven techniques, such as machine learning. These systems also provide research opportunities in developing novel methodologies for channel estimation, near-field beam split, waveform design, and beam misalignment. © 1986-2012 IEEE.
Thermal annealing effects on the structural and electrical properties of Ag2La thin films deposited by thermal evaporation technique
(Digest Journal of Nanomaterials and Biostructures Vol. 19, No. 2, April - June 2024, p. 909 - 917, 17.06.2024) Qasrawi Atef Fayez; Zakarneh Wafa
thermal annealing process. The thermally heated of films at 200 oC increased the crystallite sizes and improved the crystalline structure of the films. For these films the electrical conductivity measurements which were handled in the temperature range of 300- 440 K. The conductivity analyses indicated that the transport of charged particles is dominated by the thermionic emission and by the variable range hopping conduction mechanisms. The annealing of films shifted the impurity levels and decreased; the degree of disorder, the average hopping distance and the average hopping energy.
Thermal annealing effects on the structural and electrical properties of Ag2La thin films deposited by thermal evaporation technique
(Digest Journal of Nanomaterials and Biostructures, 17/06/2024) Qasrawi Atef Fayez; Zakarneh Wafa
thermal annealing process. The thermally heated of films at 200 oC increased the crystallite sizes and improved the crystalline structure of the films. For these films the electrical conductivity measurements which were handled in the temperature range of 300- 440 K. The conductivity analyses indicated that the transport of charged particles is dominated by the thermionic emission and by the variable range hopping conduction mechanisms. The annealing of films shifted the impurity levels and decreased; the degree of disorder, the average hopping distance and the average hopping energy.
Bi2O3 nanosheets- based photodetectors designed for visible light communication technology
(Physica Scripta (IOP), 17.03.2025) QAsrawi Atef Fayez; Zanoon Tateq; Alawneh Isam; Khanfar Hazem
In this work, n-type bismuth oxide nanosheets deposited onto n-type silicon substrates by a vacuum evaporation technique under a vacuum pressure of 10−5 mbar is fabricated to perform as a daylight photodetectors suitable for visible light and infrared communication technology. The n-Si/n-Bi2O3 heterojunction devices exhibited conduction and valence band offsets of 0.89 eV 0.73 eV, respectively. Two Schottky barriers Pt/n-Si and Pt/Bi2O3 of respective barrier heights of 1.65 eV and 0.76 eV are formed on the sides of the heterojunction devices. Dark electrical characterization on the Pt/n-Si/n-Bi2O3/Pt hybrid structure showed a maximum current rectification ratio of 166. The current transport mechanism in the devices was dominated by the Richardson –Schottky thermionic conduction type and by electric field assisted charge carrier tunneling within a barrier of width and height of 60 nmand 0.83 eV, respectively. On the other hand, electrical measurements handled under the illumination of a daylight mini-lamp have shown that the photodetectors under focus exhibit maximum current responsivity, external quantum efficiency percentage, specific detectivity and linear dynamic range of 30 AW−1, 3000%, 1.7´1012 Jones and 36.4 dB under illumination power of 82 μW, respectively. The features of the bismuth oxide based photodetectors nominate them for visible and infrared lights illumination technology.
Thermal annealing effects on the structural and electrical properties of Ag2La thin films deposited by thermal evaporation technique
(Virtual co physics SRL, 2024) Qasrawi, Atef Fayez; Zakarneh, Wafaa Ahmad
Herein Ag2La thin films are fabricated by a vacuum coating method and subjected to a thermal annealing process. The thermally heated of films at 200 C-o increased the crystallite sizes and improved the crystalline structure of the films. For these films the electrical conductivity measurements which were handled in the temperature range of 300440 K. The conductivity analyses indicated that the transport of charged particles is dominated by the thermionic emission and by the variable range hopping conduction mechanisms. The annealing of films shifted the impurity levels and decreased; the degree of disorder, the average hopping distance and the average hopping energy.
Effects of ZnPc substrates on the electro‑optical properties of MgSe thin films and the applications of Al/ZnPc/MgSe/ (Ag, C, Au) hybrid devices as resonant negative capacitance sources
(Optical and Quantum Eletronics, Springer link, 11/07/2024) Qasrawi Atef Fayez
Herein, polycrystalline magnesium selenide (MgSe) thin films are deposited onto glass and monoclinic-structured zinc phthalocyanine (ZnPc) thin film substrates under high vacuum pressure using the thermal evaporation technique. ZnPc substrates improved the crystallinity of the MgSe films and decreased the stacking faults percentages and defect concentration by 31.57 and 52.49%, respectively. MgSe films deposited onto ZnPc substrates exhibited a notable increase of up to 32% in light absorption within the visible spectrum, while maintaining the energy band gap value of MgSe without significant alteration. In addition, as both the substrate and the epilayer exhibited p-type conductivity, an isotype heterojunction device structure is formed at the ZnPc/MgSe interfaces. The valence and conduction band offsets for this interface are 0.81 and 1.16 eV, respectively. On the other hand, re-fabrication of the ZnPc/MgSe heterojunctions onto Al thin film substrates and forming three Ag/MgSe, C/MgSe, and Au/MgSe Schottky channels on the epilayer surface allowed wide control of the negative capacitance effect and the resonance-antiresonance (RA) peaks in the capacitance spectra of the Al/ZnPc/MgSe/(Ag, C, Au) hybrid devices. These two important RA and NC features of the device can also be engineered by altering the DC biasing of the device. Moreover, Lorentz model analyses on the capacitance spectra showed an increased density of oscillators and increased scattering time constant with decreasing built-in potential at the metal/MgSe interfaces. The features of the hybrid devices presented make the device promising for microwave and electro-optical applications
Design and Characterization of Se/Nb2 O5 Interfaces asHigh Infrared- Absorbers and High Frequency Band Filters
(Crystal Research and Technology, Wiley, 07/12/2024) QAsrawi Atef Fayez; Daragme B. Rana
Herein a new class of optoelectronic devices beneﬁcial for infrared light absorption and high-frequency application in the terahertz frequency domain are designed and fabricated. The devices are formed by coating a highly transparent thin layer of Nb2 O5 onto a selenium-thin ﬁlm to form Se/Nb 2 O5(SNO) optical interfaces. Although coating of Nb 2 O5 nanosheets decreased the crystallite sizes and increased the strain and defect concentration in the hexagonal structured Se ﬁlms, they successfully increased the light absorption by ≈148% in the infrared range of light. A blueshift in the energy band gap of Se from 2.02 to 2.30 eV is observed. The coating of the Nb2 O5onto Se suppressed the free carrier absorption in Se and Nb 2 O5 . As dielectric active layers, SNO interfaces showed a major resonance dielectric peak centered at 1.67 eV. The optical conductivity and terahertz cutoﬀ frequency analyses which are handled using the Drude-Lorentz approach revealed the highest drift mobility and free carrier concentration of 17.17 cm 2 Vs−1 and5.0 × 1017 cm−3 when an oscillator of energy of 1.75 eV is activated. In addition, the terahertz cutoﬀ frequency spectra which varied in the range of4.0–131 THz showed the suitability of the SNO devices for terahertz technology and other optoelectronics
Power regulation of variable speed multi rotor wind systems using fuzzy cascaded control
(Nature research, 2024) Benbouhenni, Habib; Çolak, İlhami; Bizon, Nicu; Mosaad, Mohamed I.; Tella, Teshome Goa
Power quality is a crucial determinant for integrating wind energy into the electrical grid. This integration necessitates compliance with certain standards and levels. This study presents cascadedfuzzy power control (CFPC) for a variable-speed multi-rotor wind turbine (MRWT) system. Fuzzy logic is a type of smart control system already recognized for its robustness, making it highly suited and reliable for generating electrical energy from the wind. Therefore, the CFPC technique is proposed in this work to control the doubly-fed induction generator (DFIG)-based MRWT system. This proposed strategy is applied to the rotor side converter of a DFIG to improve the current/power quality. The proposed control has the advantage of being model-independent, as it relies on empirical knowledge rather than the specific characteristics of the DFIG or turbine. Moreover, the proposed control system is characterized by its simplicity, high performance, robustness, and ease of application. The implementation of CFPC management for 1.5 MW DFIG-MRWT was carried out in MATLAB environment considering a variable wind speed. The obtained results were compared with the direct power control (DPC) technique based on proportional-integral (PI) controllers (DPC-PI), highlighting that the CFPC technique reduced total harmonic distortion by high ratios in the three tests performed (25%, 30.18%, and 47.22%). The proposed CFPC technique reduced the response time of reactive power in all tests by ratios estimated at 83.76%, 65.02%, and 91.42% compared to the DPC-PI strategy. Also, the active power ripples were reduced by satisfactory proportions (37.50%, 32.20%, and 38.46%) compared to the DPC-PI strategy. The steady-state error value of reactive power in the tests was low when using the CFPC technique by 86.60%, 57.33%, and 72.26%, which indicates the effectiveness and efficiency of the proposed CFPC technique in improving the characteristics of the system. Thus this control can be relied upon in the future.
Barium Oxide Thin Films Designed as Electro-OpticalGigahertz/Terahertz Filters
(Crystal Research and Technology, Wiley, 23.02.2025) QAsrawi Atef Fayez; Alharbi Seham; Laila H. Gaabour
Herein barium oxide thin ﬁlms are studied as a promising electro-opticalsystem. The deposited ﬁlms exhibited a polycrystalline tetragonalstructure and are composed of a mixture of BaO and BaO2 . The p-type ﬁlmsare highly transparent (80%) with an energy band gap of 3.55 eV containingexponential band tails of widths of 1.22 eV. Analyses using the Drude-Lorentzmodel demonstrated the ﬁlms suitability for nonlinear optical applications,with optical conductivity parameters revealing a scattering time constantin the range of 0.4–1.8 fs, a free hole concentration of 10 18−10 19 cm−3 anddrift mobility values of 0.70–3.16 cm 2 Vs−1 . Terahertz cutoﬀ frequency spectra calculations indicated the ﬁlms capability as eﬃcient terahertz band ﬁlterswith a cutoﬀ frequency range of 3.2–193.0 THz. Additionally, the nonlinear third-order optical susceptibility increased with decreasing incident photonenergy. Applying an AC signal with a driving frequency of 0.01–1.40 GHz across the terminals of Yb/BaO/Ag devices revealed a high cutoﬀ frequency (≈9 GHz)in the microwave frequency domain. These properties highlight the potential ofBaO ﬁlms as nonlinear optical ﬁlters and microwave waveguides, positioningthem as candidates for gigahertz/terahertz technology applications
Electro-optical dynamics in SnO2 designed as negative resistance sources and gigahertz/terahertz band filters
(Optical and Quantum Electronics, springer link, Mayis 2024) Qasrawi Atef Fayez; Kmail Bayan
Amorphous thin films of SnO2, prepared by a vacuum evaporation technique under a pressure of 10− 5 mbar, are employed as electro-optical filters suitable for microwave, infrared, and visible light communication technologies. The filters perform as optical layers, exhibiting optical transitions within an energy band gap of 3.62 eV, with the band gap containing energy band tails of widths of 0.63 eV. In addition, dielectric dispersion analyses on the optical filters show their ideality for high k-gate dielectric applications. Wide tunability in the dielectric response is observed in these films. Moreover, analyses of the optical conductivity and terahertz cutoff frequency spectra have shown that SnO2 films exhibit resonance of optical signals suitable for infrared and visible light communication technology as well. When excited with infrared light of energy of 1.38 eV, the drift mobility and free hole concentration in these films reach 11.72 cm2/Vs and 2 × 1017 cm− 3, respectively. Furthermore, the device exhibits a negative resistance effect in the microwave range of 0.1–1.80 GHz, and terahertz cutoff frequency values in the range of 10 GHz − 48 THz. The features of the SnO2 electro-optical band filter make them attractive for communication technology extending from 5G/6G to IR and reaching visible light communications.
Electro-optical dynamics in SnO2 designed as negative resistance sources and gigahertz/terahertz band filters
(Springer, 2024) Kmail, Bayan H.; Qasrawi, Atef Fayez
Amorphous thin films of SnO2, prepared by a vacuum evaporation technique under a pressure of 10(- 5) mbar, are employed as electro-optical filters suitable for microwave, infrared, and visible light communication technologies. The filters perform as optical layers, exhibiting optical transitions within an energy band gap of 3.62 eV, with the band gap containing energy band tails of widths of 0.63 eV. In addition, dielectric dispersion analyses on the optical filters show their ideality for high k-gate dielectric applications. Wide tunability in the dielectric response is observed in these films. Moreover, analyses of the optical conductivity and terahertz cutoff frequency spectra have shown that SnO2 films exhibit resonance of optical signals suitable for infrared and visible light communication technology as well. When excited with infrared light of energy of 1.38 eV, the drift mobility and free hole concentration in these films reach 11.72 cm(2)/Vs and 2 x 10(17) cm(- 3), respectively. Furthermore, the device exhibits a negative resistance effect in the microwave range of 0.1-1.80 GHz, and terahertz cutoff frequency values in the range of 10 GHz - 48 THz. The features of the SnO2 electro-optical band filter make them attractive for communication technology extending from 5G/6G to IR and reaching visible light communications.
Enhanced electro-optical performance of barium oxide stacked layers via platinum nanosheets designed for wide band light absorption and terahertz technology
(Physica Scripta, 18.12.2024) QAsrawi Atef Fayez; Gaabour Laila H.; Alharbi Seham R.
In this study, stacked films of barium oxide (BaO) comprising platinum nanosheets in its structure are designed as electro-optical filters applicable in terahertz technology. The layers were fabricated by the thermal evaporation technique. It was shown that insertion of 50 nm and 100 nm thick Pt nanosheets between stacked layers of BaO improves the crystallinity of the layers by reducing the strains and defect concentrations. In addition, the light absorption and optical conduction is enhanced by more than 300%, 900% and 100 % in the ultraviolet (3.5-4.10 eV), visible (1.80-3.10 eV) and infrared (1.10-1.75 eV) ranges of light, respectively. The insertion of Pt nanosheets led to an increase in the dielectric constant (ε_r) values by over 104%. Specifically, ε_r values were initially 1.2–1.5, 1.6–1.8, and 1.8–2.0 in the ultraviolet, visible, and infrared light ranges, respectively. Upon incorporating Pt nanosheets with a thickness of 200 nm, these ε_r values increased to 1.4–1.7 in the ultraviolet, 1.8–3.6 in the visible, and 3.7–3.9 in the infrared ranges. Significant increase in the terahertz cutoff frequency from ~2.5 THz to ~15.35 THz was achieved in the infrared range of light. Moreover, the optical conductivity parameters which were obtained with the help of Drude-Lorentz electro-optical analysis showed remarkable enhancement in the free carrier concentration and in the drift mobility of the BaO optical filters from 5×〖10〗^18 cm-3 and 0.47 cm2/Vs to 7×〖10〗^18 cm-3 and 2.03 cm2/Vs to 9×〖10〗^18 cm-3 and 2.03 cm2/Vs upon insertion of Pt nanosheets of thicknesses of 100 nm and 200 nm, respectively. Furthermore, the temperature dependent electrical conductivity measurements has shown that Pt nanosheets increased the electrical conductivity of BaO by eight orders of magnitude. The features of BaO stacked layers comprising Pt nanosheets are promising for terahertz technology applications as waveguides and wideband optical filters.

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