H. Ferhati

Role of Optimized Grooves Surface-Textured Front Glass in Improving TiO 2 Thin-Film UV Photodetector Performance

In this paper, the impact of the surface-textured front glass on the absorption of TiO2/glass thin-film ultraviolet (UV) photodetector is investigated, in order to achieve the dual role of increasing the scattering of UV-light as well as reducing the refracting UV-light in the glass. The efficient control of these phenomena may lead to more electric field confinement and UV-light trapping in TiO2 absorber layer. Moreover, semianalytical modeling combined with particle swarm optimization is carried out for studying and enhancing the metal-semiconductor-metal photodetector optical and electrical performances. The results obtained from our semianalytical investigation are validated by comparison with the experimental data. It is found that the absorbance increases significantly by about 51% in optimized design over the planar structure, which is expected to improve the photodetector figures of merit. In this context, photodetector with optimized grooves texturization exhibits a 341% improvement, in terms of responsivity, in comparison with the planar structure and 275% improvement with respect to the textured device without optimization. The obtained results make the proposed design methodology a promising alternative for high-performance optoelectronic applications.

Numerical investigation of a double-junction a:SiGe thin-film solar cell including the multi-trench region

We present a new approach based on the multi-trench technique to improve the electrical performances, which are the fill factor and the electrical efficiency. The key idea behind this approach is to introduce a new multi-trench region in the intrinsic layer, in order to modulate the total resistance of the solar cell. Based on 2-D numerical investigation and optimization of amorphous SiGe double-junction (a-Si:H/a-SiGe:H) thin film solar cells, in the present paper numerical models of electrical and optical parameters are developed to explain the impact of the multi-trench technique on the improvement of the double-junction solar cell electrical behavior for high performance photovoltaic applications. In this context, electrical characteristics of the proposed design are analyzed and compared with conventional amorphous silicon double-junction thin-film solar cells.

Modeling of boron nitride-based nanotube biological sensor using neural networks

In this study, an ultrasensitive biological boron nitride-based nanotube (Bio-BNNT) sensor is modeled and investigated by means of neural approach. The type of configuration studied is a cantilevered BNNT resonator sensor with an attached mass at the tip. The idea behind our resonator sensor is based on the determination of the natural BNNT frequency shift induced by added biological mass. A multilayer perceptron neural network is used to predict the attached mass, which causes a variation of the BNNTs frequency shift with different diameters and lengths. This model is implemented in the form of a component in the ORCAD-PSPICE electric simulator library. The component should reproduce faithfully the biological sensor behavior. Moreover, we have developed an inverse model called intelligent sensor in order to remove the nonlinearity response provided by the sensor. The association of this ANN-based corrector has brought significant improvement for high sensing performance.

The role of the Ge mole fraction in improving the performance of a nanoscale junctionless tunneling FET: concept and scaling capability

In this paper, a new nanoscale double-gate junctionless tunneling field-effect transistor (DG-JL TFET) based on a Si1− xGex/Si/Ge heterojunction (HJ) structure is proposed to achieve an improved electrical performance. The effect of introducing the Si1− xGex material at the source side on improving the subthreshold behavior of the DG-JL TFET and on suppressing ambipolar conduction is investigated. Moreover, the impact of the Ge mole fraction in the proposed Si1− xGex source region on the electrical figures of merit (FoMs) of the transistor, including the swing factor and the I ON/I OFF ratio is analyzed. It is found that the optimized design with 60 atom % of Ge offers improved switching behavior and enhanced derived current capability at the nanoscale level, with a swing factor of 42 mV/dec and an I ON/I OFF ratio of 115 dB. Further, the scaling capability of the proposed Si1− xGex/Si/Ge DG-HJ-JL TFET structure is investigated and compared to that of a conventional Ge-DG-JL TFET design, where the optimized design exhibits an improved switching behavior at the nanoscale level. These results make the optimized device suitable for designing digital circuit for high-performance nanoelectronic applications.

Enhancement of the optical performance of ZnO thin-film using metallic nano-particles for optoelectronic applications

In this paper, versatile structures based on dissimilar metallic nano-particles (Ag, Au, Ti, Al) are proposed to enhance the ZnO thin film optical performance for both optoelectronic and environment monitoring applications. An Exhaustive study of the proposed structure including metallic nano-particles has been performed numerically, in order to evaluate the optical behavior of the proposed ZnO thin films against the conventional design for optoelectronic applications. The numerical computations reveal that the proposed design exhibits an outstanding capability in improving the overall device optical parameters. In addition, the proposed device with Al metallic nano-particles offers superior absorbance as well as lower reflectance as compared to the conventional design. These achievements can be attributed essentially to the localized surface plasma resonance phenomenon and the improved light trapping capability resulted from the optical confinement effect. The recorded results signify the crucial role of the proposed feature in improving the ZnO thin films optical performance, which makes it very promising to be used in the future high performance optoelectronic devices.

New phototransistor design to improve the electrical and optical performance using gate-engineering aspect

Our objective in this work is to propose a novel optically controlled field effect transistor OC-FET design by using the gate engineering paradigm. Besides, analytical analysis has been conducted and investigated for the improvement of the electrical and optical criteria related to OC-FET-based applications. By using a compact modeling framework, the comparison between the proposed Dual Gate (DG) OC-FET design against its conventional counterpart has been exploited to validate the enhanced electrical efficiency of the presented structure in terms of increased gain voltage, ION/IOFF ratio and superior drain current driving capability. The obtained results are found to be in a good agreement in comparison to that provided by the numerical results, thus confirming the precision of our modeling approach.

Investigation of GaAs/Si solar cell with interfacial defects using ANFIS technique

Our aim in this work is to emphasize the immunity behavior of the GaAs/Si heterostructure against the defects degradation. The main objective of this paper is to propose a new modeling approach using an Adaptive Network based Fuzzy Inference System (ANFIS) to investigate the electrical performance of GaAs/Si solar cell including the interface defects generated by the large lattice mismatch between Si and GaAs. The influence of the interfacial defects on the efficiency has been conducted by extensive simulation using both Atlas 2-D numerical simulator and ANFIS-based computation in order to predict the device behavior under critical conditions. The developed approach can provide many benefits for circuit simulators such as SPICE and PC1D which allows robust optimization of photovoltaic circuit performances.

Investigation of analog/RF performance of gate-all-around junctionless MOSFET including interfacial defects

In this paper, an analytical drain current model for cylindrical gate-all-around junctionless GAAJ MOSFET including the interfacial hot-carrier degradation effects is presented. A quantitative study of analog/RF parameters like transconductance, cut-off frequency, drain current drivability and voltage gain has been carried out to investigate the overall analog/RF device performance degradation due to the hot carrier induced damage in the form of localized/fixed charges at the semiconductor/oxide interface. Based on the obtained results, we have found that the degradation of the drain current, transconductance, gain and cutoff frequency tends to be important with increasing of the interface charge densities, which can degrade strongly the device reliability for analog/RF applications. Our obtained results showed that the analytical model is in close agreement with the 2-D numerical simulation over a wide range of device parameters.

Semi-analytical modeling and optimization of a: SiGe thin-film solar cell including multi-trench region

In this paper, we present semi-analytical modeling and optimization approaches based on genetic algorithm computation to improve the electrical performance of amorphous SiGe thin-film solar cell including multi-trench region. The key idea behind the proposed investigation is to model the electrical efficiency using 2D numerical database and analytical fitting. Semi-analytical expression of the efficiency for the trench-dependent electrical models, have been used to estimate the performance of the investigated a:SiGe thin-film solar cell. Trench-dependent model includes the multi-trench region parameters, which are: the doping, thickness and width. The semi-analytical model has been used to formulate the objective function where multi-trench region, its geometry dependence and doping profile are considered simultaneously. The proposed approach is used to search for solar cell design parameters that optimize the electrical performance. The obtained results are validated with 2D numerical data, where a good agreement is recorded. The proposed semi-analytical analysis may provide a practical basis to investigate and optimize the a:SiGe-based solar cells for low cost and high performance applications.