The quasiparticle band structures and optical properties of ACdTS kesterite are investigated here on the basis of first-principles calculations, including the many-body effects theory, by using the GW plus Bethe-Salpeter equation. There were significant GW-quasiparticle corrections, over 0.9 eV, to the GGA-Kohn-Sham band gap. Our calculations also show that ACdTS kesterite had a small binding energy, exhibited optical absorption in the visible region, high minority carrier mobility, and large diffusion in length, rendering this material a promising candidate for solar cells. Based on these findings, we designed and implemented an ACdTS absorber in a thin-film solar cell (TFSC) structure. The new kesterite solar cell has a high efficiency of 11.6% with a low deficit in the output voltage. Moreover, a strategic combination between the particle swarm optimization approach and the ACdTS TFSC decorated with periodic nanowires is proposed to obtain significantly improved photovoltaic characteristics. The optimized design identifies a new pathway for a high conversion efficiency of 14%, far surpassing that provided by the conventional TFSC kesterite.

Skin detection is very challenging because of the differences in illumination, cameras characteristics, the range of skin colours due to different ethnicities and many other variations. New effective and accurate methodologies are developed for skin colour detection to easily identify human's skin colour threw databases which are specifically designed to assist research in the area of face recognition. One of these is the recently built SFA database that showed high accuracy for segmentation of face images. The approach described in this paper exploits skin and non-skin samples provided by SFA for skin segmentation on the basis of the well-known Euclidean and Manhattan distance metrics. Most importantly, the scheme proposed tries to segment facial colour images inside or outside SFA by means of skin samples belonging to SFA. Simulation results in both SFA and UTD colour face databases indicate that detection rates higher than 95% can be achieved with either measure.

In this work, an inverted PTB7:PC₇₀BM bulk heterojunction solar cells with the configuration of ITO/ZnO/ PTB7:PC₇₀BM / HTMs/Ag for various inorganic materials as a hole transport layer (ZnO, MoO₃, NiO, PEDOT: PSS, V₂O₅ and Cu₂O) are simulated by using the GPVDM software which is a free general-purpose tool for the simulation of opto-electronic devices. The influence of the thickness of both PTB7:PC₇₀BM and HTMs layers on the performance of the solar cell are investigated. The obtained results indicated that on regardless on the type of the inorganic material constituted the Hole Transport Material (HTM), the solar cell parameters can be improved by reducing the HTM thickness while the active layer optimum thickness is around 90 nm. The performance of the device with all inorganic materials used as HTM reaches the same levels as the PEDOT/PSS for the lower thickness (10 nm). As the thickness is increased, the electrical parameters are significantly enhanced by inserting cuprous oxide (Cu₂O) compared to the conventional PEDOT: PSS.

A new multispectral InGaZnO (IGZO) thin-film phototransistor (TF PT) based on a graded band-gap (GBG) SiGe capping layer with metallic nanoparticles (MNPs) is proposed. An accurate drain-current model is developed to investigate the device performances, where the optical characteristics under different light excitations (530 nm, 820 nm, and 1550 nm) are analyzed using the 3-D Finite-difference time-domain method (FDTD). It is found that the proposed device shows high photoresponse characteristics. Besides, it is revealed that the GBG configuration, MNPs spatial distribution and size can induce a complex behavior, which influences the device photoresponse over multiple spectral bands. Importantly, an iterative decision-maker framework based on the Multi-Objective Genetic Algorithm (MOGA) metaheuristic approach is implemented to design efficient multispectral IGZO TF PT. It is demonstrated that the proposed MOGA-based scheme paves the way for the designer to identify the appropriate GBG profile and MNPs spatial distribution for highly-responsive devices at selective Visible and IR wavelengths and to realize high-performance multispectral sensors. The proposed approach based on combining the proposed IGZO TF PT structure with MOGA metaheuristic computation opens up a new strategy for the design and experimental fabrication of high-performance multispectral optoelectronic devices.

In this paper, a new high-performance tunable band-selective (UV-Visible) photodetector (PD) based on RF sputtered a-SiC active layer is demonstrated. SiC thin-films were deposited on glass substrate by RF magnetron sputtering method at different sputter power values ranging from 60 W to 120 W. The samples morphological, structural, optical and photodetection properties were investigated by carrying out XRD, SEM, EDS, UV-Vis spectroscopy and photoresponse measurements. It was revealed that the sputtering power could modulate the optical behavior of a-SiC alloy, tuning favorable visible absorbance at high sputter power. This phenomenon is correlated with the influence of the RF power on the SiC film structural properties and compositions. Interestingly, measurements showed that a-SiC PD elaborated at 60 W of RF power can detect UV radiation with a high responsivity of 138 mA/W, low noise effects, superior detectivity of 7.8 × 10¹² Jones, while maintaining the visible blindness property. On the other hand, the prepared device at high sputtering power exhibits extended photoresponse characteristics, yielding 426 mA/W and 77 mA/W of responsivity values over UV and visible ranges, respectively. Therefore, the present investigation can provide a new strategy for the design and fabrication of photodetector devices based on SiC platform with broadband and solar-blind adjustable sensing purposes according to the desired application.

Skin detection is very challenging because of the differences in illumination, cameras characteristics, the range of skin colours due to different ethnicities and many other variations. New effective and accurate methodologies are developed for skin colour detection to easily identify human's skin colour threw databases which are specifically designed to assist research in the area of face recognition. One of these is the recently built SFA database that showed high accuracy for segmentation of face images. The approach described in this paper exploits skin and non-skin samples provided by SFA for skin segmentation on the basis of the well-known Euclidean and Manhattan distance metrics. Most importantly, the scheme proposed tries to segment facial colour images inside or outside SFA by means of skin samples belonging to SFA. Simulation results in both SFA and UTD colour face databases indicate that detection rates higher than 95% can be achieved with either measure.

In this paper, the leaky acoustic microwaves (LAW) in a piezoelectric substrate (Lithium Niobate LiNbO3 Cut Y-X) were studied. The main method for this research was classification using a probabilistic neural network (PNN).The originality of this method is in the accurate values it provides. In our case, this technique was helpful in identifying undetectable waves, which are difficult to identify by classical methods. Moreover, all the values of the real part and the imaginary part of the coefficient attenuation with the acoustic velocity were classified in order to build a model from which we could easily note the Leaky waves. Accurate values of the coefficient attenuation and acoustic velocity for Leaky waves were obtained. Hence, in this study, the focus was on the interesting modeling and realization of acoustic microwave devices (radiating structures) based on the propagation of acoustic microwaves

The quasiparticle band structures and optical properties of ACdTS kesterite are investigated here on the basis of first-principles calculations, including the many-body effects theory, by using the GW plus Bethe-Salpeter equation. There were significant GW-quasiparticle corrections, over 0.9 eV, to the GGA-Kohn-Sham band gap. Our calculations also show that ACdTS kesterite had a small binding energy, exhibited optical absorption in the visible region, high minority carrier mobility, and large diffusion in length, rendering this material a promising candidate for solar cells. Based on these findings, we designed and implemented an ACdTS absorber in a thin-film solar cell (TFSC) structure. The new kesterite solar cell has a high efficiency of 11.6% with a low deficit in the output voltage. Moreover, a strategic combination between the particle swarm optimization approach and the ACdTS TFSC decorated with periodic nanowires is proposed to obtain significantly improved photovoltaic characteristics. The optimized design identifies a new pathway for a high conversion efficiency of 14%, far surpassing that provided by the conventional TFSC kesterite.

Cost-effective multispectral photodetectors (PDs) exhibiting a high UV-Visible-NIR photoresponse offer an avenue for developing environmental monitoring devices, imaging sensors, object discrimination, and optical links. However, PDs based on a single semiconductor as light-sensitive layer are unable to provide broadband photodetection properties. In this work, a new PD device based on ZnO-ZnS Microstructured Composite (MC) which achieves a high UV-Visible-NIR photoresponse is demonstrated. The ZnO-ZnS MC is elaborated by combining vacuum thermal evaporation technique and a suitable annealing process. Scanning Electron Microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and UV-Vis-NIR spectroscopy were used to elucidate the morphological, structural and optical properties of the prepared sample. It was demonstrated that the ZnO-ZnS MC can be useful to enhance the visible absorbance efficiency by promoting efficient light-scattering effects. It is revealed that the prepared UV-Vis-NIR PD offers a low dark current of 5 nA, a high I_ON/I_OFF ratio of 78 dB and an enhanced responsivity in UV, visible and NIR ranges. The proposed multispectral PD demonstrates a high I_ON/I_OFF current ratio under self-powered working regime. Therefore, the proposed ZnO-ZnS MC is believed to provide new insights in developing efficient, self-powered and low-cost multispectral PDs for high-performance optoelectronic systems.

In this paper, we propose a full-wave analysis for characterizing the resonant frequencies and bandwidths of high-temperature superconductor inverted microstrip printed on anisotropic substrates. Our proposed approach is based on Galerkin procedure in the Fourier transform domain (FTD) combining with the complex resistive boundary condition. With the use of suitable Green's functions in the FTD, the analysis is performed for the case where the superconducting rectangular patches printed on anisotropic substrate. The numerical results obtained using the proposed approach are compared with previously published numerical results computed by means of the electromagnetic simulator “IE3D software”. These comparisons were very good, which prove the correctness and the validity of the proposed method. It is found that the optical properties combined with optimally chosen structural parameters of anisotropic materials can be maintaining control of the resonant frequency and exhibiting wider bandwidth characteristics.

In this study, an efficient full-wave method is developed for characterizing the resonant frequencies, bandwidths, and quality factors of an inverted circular superconducting patch antenna. Our technique is based on the Galerkin procedure in the Hankel transform domain (HTD) combined with the complex resistive boundary conditions. With the use of suitable Green’s functions in the HTD, the analysis is performed for the case where the superconducting circular patches is printed on an anisotropic substrate. The numerical results obtained using this approach are compared with the experimental results. These comparisons were very good, which proves the correctness and the validity of the method. It is found that the optical properties combined with optimally-chosen structural parameters of anisotropic materials can maintain control of the resonant frequency and exhibit wider bandwidth characteristics.

In this work, an efficient analysis is presented to accurately predict the resonant frequency and bandwidth of superconducting microstrip antenna fed through a slot cut into the ground plane. The effect of the superconductivity of the rectangular patch is introduced in the Full-wave analysis based on Gorter-Casimir two fluid model together with London brothers equations. In order to check the accuracy of the proposed approach, the obtained results have been compared with theoretical and experimental data reported in the literature. Finally, the influence of the slot on the resonant frequency and half-power bandwidth of the superconducting antenna has been investigated. 

This chapter focuses on double gate (DG) Tunneling Field Effect Transistor (TFET), having band engineering and high - k dielectrics. The basic structure of TFET device is derived and developed by p-i-n diode, containing two heavily doped degenerated semiconductor “p” and “n” regions and lightly doped intrinsic “i” region, respectively. The chapter explores the idea of high-k dielectric engineering as well as band engineering concept with DG -TFET. TFET is a type of field effect device in which current transport phenomena occur due to quantum tunneling between source and channel. The estimation of device characteristics and performance of TFET is time consuming and costly due to lack of rapid advancement in technology. TFET devices have become the most popular switching device among semiconductor players. The chapter summarizes the obtained results by popular device analysis technique, modeling and simulation of DG -TFET.

In this paper, the role of introducing Germanium (Ge)/IGZO heterostructure in enhancing the Infrared (IR) photodetection properties of thin-film phototransistor (Photo- TFT) is presented. Numerical models for the investigated device are developed using ATLAS device simulator. The influence of Ge photosensitive layer thickness on the sensor IR photoresponse is carried out. It is revealed that the optimized IR Photo-TFT based on p-Ge/IGZO heterojunction can offer improved IR responsivity of 4.1×10(exp2) A/W, and over 10(exp6) of sensitivity. These improvements are attributed to the role of the introduced p-Ge/IGZO heterostructure in promoting IR photodetection ability and improved separation and transfer mechanisms of photo-exited electron/hole pairs. The photosensor is then implemented in an optical inverter gate circuit in order to assess its switching capabilities. It is found that the proposed phototransistor shows an improved optical gain thus indicating its excellent performance. Therefore, providing high IR responsivity and low dark noise effects, the optimized Ge/IGZO IR Photo-TFT can be a potential alternative photosensor for designing optoelectronic systems with high-performance and ultralow power consumption.

In this paper, a new efficient and low-cost Schottky Diode (SD) based on a-Si/Ti structure was elaborated using RF magnetron sputtering technique. An exhaustive investigation of structural and electrical properties was performed, where the sputtered device was characterized using X-ray diffraction (XRD) and Keithley (4200-SCS) to measure the current-voltage characteristics. Moreover, a comprehensive study regarding the impact of the Ti layers on the device characteristics is carried out. It was demonstrated that implementing Ti intermediate layers could induce depletion regions at the interfaces, leading to significantly enlarged voltage barrier height. Furthermore, the elaborated SD exhibits a rectification behavior providing an appropriate current with a favorable ideality factor. This is mainly due to the reduced series resistance of the multilayer structure as confirmed by electrical analysis. Therefore, the proposed SD structure based on Ti intermediate layers provides improved performance and can open a new route for the fabrication of promising alternative devices for microelectronic and sensing applications.

Tunnel FETisone of thealternativedevicefor low power electronics having steep subthreshold swing and lower leakage current than conventional MOSFET. In this research work, we have implemented the idea of high -k gate dielectric ondouble gate Tunnel FET, DG-TFETfor improvement of device features.An extensive investigation for the analog/RF and linearity feature of DG-TFET has been donehere for low power circuit and system development.Several essential analog/RF and linearity parameters like transconductance(gm), transconductance generation factor (gm/IDS) its high-order derivatives (gm2, gm3), cut-off frequency (fT), gain band width product (GBW), transconductance generation factor (gm/IDS) has been investigated for low power RF applications.The VIP2, VIP3, IMD3, IIP3, distortion characteristics (HD2, HD3), 1- dB the compression point, delay and power delay product performancehave also been throughly studied.It has been observed that the device features discussed for circuitry applications are found to be sensitiveto of gate materials, design configuration and input signals.

Tunnel FET is one of the promising devices advocated as a replacement of conventional MOSFET to be used for low power applications. Temperature is an important factor affecting the performance of circuits or system, so temperature associated reliability issues of double gate Tunnel FET and its impact on essential circuit design components have been addressed here. The temperature reliability investigation is based on double gate Tunnel FET, containing Si_1-xGe _x /Si, source/channel and HfO₂ high-k gate dielectric material. During investigation, it has been found that at high temperature application range ~ 300 K - to - 600 K,the Tunnel FET device design parameters exhibit weak temperature dependency with switching current (I_ON), while the off-state current (I_OFF) is slightly varying ~10⁻¹⁷A/μm-to-10⁻¹⁰A/μm. In addition, the impact of temperature on various device design element such as V_TH(i.e.,switching voltage),on-current (I_ON), off-current (I_OFF), switching ratio (I_ON/I_OFF) and average subthreshold slope (i.e., SS_avg), ambipolar current (I_AMB) have been done in this research work.The essential circuit design components for digital and analog/RF applications, such as current amplification factor(g_m) and its derivative (g_m’),the C-V components of device design, Cgg, Cgd and C_gs, cut - off frequency (ƒ_T) and gain band width (GBW) product have deeply investigated. In conclusion, the obtained results show that the designed double gate Tunnel FET device configuration and its circuit design components are suitable for ultra-low power circuit,system applications and reliable for hazardous temperature environment.

The development of CZTS-based solar cells is limited by two factors, the low open circuit voltage and the conversion efficiency. This is why, in this study, the impact of Cu2ZnSnS4 (CZTS) absorber thin layer parameters on the performance of the proposed MoS2/CZTS/CdS/ZnO heterostructure is simulated by the standard software SCAPS-1D. The improving output performances of this structure; the open circuit voltage (Voc), the short circuit current density (Jsc), the fill factor (FF) and the efficiency (h) are obtained by varying the absorber layer thickness, acceptor carrier concentration NA and taking into account the effect of the electron work function of the back metal contact. The optimized cell provides an energy conversion efficiency of 15.23% (Voc = 0.99 V, Jsc = 21.89 mA/cm2, FF = 69.79%) for an optimal thickness of 2 μm, a doping of 1×1016 cm-3. Performance enhancement of the proposed solar cell is subject to the back metal contact, the optimal simulated value of 5.7 eV of which represents that of the Platinum’s work function Pt. The interest of this simulation makes it possible to adjust the solar cells dimensions, optimize the absorbent layers doping, choose appropriately the back metal contact and therefore help to considerably reduce the various recombination phenomena as well as the secondary phases.

Among the causes of the degradation of the performance of kesterite-based solar cells is the wrong choice of the n-type buffer layer which has direct repercussions on the unfavorable band alignment, the conduction band offset (CBO) at the interface of the absorber/buffer junction which is one of the major causes of lower VOC. In this work, the effect of CBO at the interface of the junction (CZTS/Cd(1-x)ZnxS) as a function of the x composition of Zn with respect to (Zn+Cd) is studied using the SCAPS-1D simulator package. The obtained results show that the performance of the solar cells reaches a maximum values (Jsc = 13.9 mA/cm2 , Voc = 0.757 V, FF = 65.6%, ɳ = 6.9%) for an optimal value of CBO = -0.2 eV and Zn proportion of the buffer x = 0.4 (Cd0.6Zn0.4S). The CZTS solar cells parameters are affected by the thickness and the concentration of acceptor carriers. The best performances are obtained for CZTS absorber layer, thichness (d = 2.5 µm) and (ND = 1016 cm-3 ). The obtained results of optimizing the electron work function of the back metal contact exhibited an optimum value at 5.7 eV with power conversion efficiency of 13.1%, Voc of 0.961 mV, FF of 67.3% and Jsc of 20.2 mA/cm2 .