To boosting the performance of inverted p-i-n-type planar hetero-junction architecture photovoltaic cells based on CH3NH3PbI3 perovskite materials, a thin buffer layer Bathocuproine (BCP) is introduced between the Electron Transporting Layer (ETL) PCBM and the metal contact. The trends in parameters Perovskite Solar Cells (PSCs) inserting BCP is studied using solar cell capacitance simulator (SCAPS-1D). The obtained results of optimizing the thickness of the Bathocuproine (BCP) buffer layer exhibited optimum value at 5 nm, with power conversion efficiency (PCE) of 17.30 %, VOC of 1.39 V, and FF of 62.89 %. The carrier concentration was higher than 1017 cm-3 increases sharply the conversion efficiency by about 0.35-2.3 %. Further, the lower metal work function (Фm<4.3 eV) enhances the electrical parameters where the efficiency up to 21.3 %.
Zinc Oxide (ZnO) and Nickel Oxide (NiO) thin films were prepared using the spray pyrolysis technique using three different quantities of solution 5, 10, and 15 ml, to modify their optical properties. Optical characterization of the obtained thin films showed that the bandgap and the transparency of NiO and ZnO decrease with increasing solution quantity. The films are highly transparent making them suitable for optoelectronic applications. It is worth noting that NiO has a low growth rate compared to ZnO due to its larger bandgap. The different parameters obtained for both films are then used to simulate the electrical characteristics and the responsivity of a NiO/ZnO heterojunction based PN photodiode. Both the electrical characteristics and the responsivity improve with increasing quantities of solution. These findings may help to find an optimal design for photodiode fabrication.
In this paper, novel self-powered, solar-blind UV photodetector (PD) designs based on a ZnO thin-film with engineered back metal layer (BML) were fabricated by RF magnetron sputtering and e-beam evaporation techniques. An exhaustive study concerning the impact of dissimilar BML (Au and Ni) on the device structural, optical and electrical properties was carried out. The measured I–V curves illustrated an asymmetrical behavior, enabling a clear and distinctive photovoltaic mode. Superb sensitivity of 107, high ION/IOFF ratio of 149dB, ultralow dark-noise current less than 11pA and responsivity exceeding 0.27A/W were reached for the prepared ZnO-based UV-PDs in self-powered mode. The role of the engineered BML in promoting effective separation and transfer of the photo-induced carriers was discussed using the band-diagram theory. The influence of the annealing process on the UV-sensor performance was also investigated. The annealed device at 500°C demonstrated a lower dark current of a few picoamperes and a high rejection ratio of 2.2×103, emphasizing its exciting visible blindness characteristics. Therefore, the use of an engineered BML with optimized annealing conditions open up new perspectives to realizing high-performance, self-powered solar-blind UV-PDs based on simple thin-film-ZnO structure strongly desirable for various optoelectronic applications.
The mechanical behavior of few-layered borophene (η-LB), at different temperatures ranging from 10 to 800 K in conjunction with a variant strain-rate, is studied by employing molecular dynamics simulations based on the Stillinger-Weber potential. The uniaxial tensile deformations along the zigzag- and armchair-direction of the hexagonal lattice are considered for η-LB, with η = 1, 2, 3, 4. We find an extremely anisotropic mechanical response. Parameters such as Young’s modulus and fracture strength are higher along the armchair-traction than the zigzag one due to the corrugated structure along the zigzag-axis. The fracture resistances of η-LB are strongly sensitive to temperature, while their dependence on the strain-rate is relatively low. The influence of nitrogen intercalation as well as vacancy defects on elastic behavior is also determined and discussed. The results are significantly affected by the defect’s type, concentration, and location. Our findings provide useful insights for the design of LB for many applications requiring a practical large magnitude strain engineering.
In this paper, a new UV-photodetector (UV PD) design based on non-hydrogenated amorphous-silicon (a-Si) was fabricated using RF magnetron sputtering technique. The proposed structure consists on sputtering an ITO thin-film acting as a passivation layer on the a-Si layer to form a heterostructure design compatible with silicon photonics technology. X-Ray Diffraction (XRD) and UV–Vis spectra were carried out to assess the device structural and optical properties. Measurements emphasized the amorphous state of the sputtered Si thin-film. Interestingly, it was found that the elaborated device shows an exciting UV absorption capability (over than 95%) with drastically reduced visible photoresponse. The elaborated ITO/a-Si UV PD exhibits an ultra-low dark current less than 1 pA, a good responsivity of 0.13 A/W and a high ION/IOFF ratio of 2.5 × 104. Besides, the device demonstrates a high UV-to-Vis ratio exceeding 2.3 × 103, thus confirming its visible blindness property. These enhancements are attributed to the role of ITO/a-Si heterostructure in promoting near-perfect UV absorption. In addition, this structure generates an electric field acting as effective driving force of the photo-induced e/h pairs, which leads to enhance the device generation/collection efficiency. Therefore, the use of ITO/a-Si design opens up new pathways for designing novel solar-blind UV PDs potentially appropriate for integrated silicon photonics technology.
This work aims to investigate the performance of a new Junctionless (JL) Ge-gate Tunneling-FET phototransistor for Infrared sensing applications. The electrical and optical performances of the considered sensor are numerically analyzed, where both switching and optoelectronic properties are reported. In this context, we address the influence of the Ge-gate doping level and high-k gate dielectric on the variation of optical Figures-of-Merit (FoMs) parameters such as responsivity, ION/IOFF ratio and optical commutation speed. Interestingly, it was revealed that the proposed design provides promising pathways for enhancing the phototransistor FoMs as compared to the conventional FET-based sensors. In the second stage of our investigation, we provide a performance assessment of the proposed phototransistor by analyzing its switching capabilities as compared to the conventional design, where the device is implemented in an optical inverter circuit. The obtained results indicate the superior optoelectronic performance offered by the proposed design in comparison with the conventional devices in terms of optical commutation speed and optoelectronic gain. Therefore, this contribution can provide new insights concerning the benefit of adopting JL-TFET design for future high-performance and ultra-low power deep submicron CMOS optoelectronic applications.
Pb0 centers are the main defects at the Si(100)/SiO2 interface in conventional MOS transistors. Besides, the charge pumping (CP) technique in which a MOSFET is repeatedly switched between inversion and accumulation has been widely used for studying single capture/emission events in deep submicron transistors. In CP, the minority carriers stored into interface traps in inversion recombine in accumulation with majority carriers from the substrate (n-channel case). This provides a CP current which can be studied. When it was accepted that in submicron MOSFETs the CP current was given by Icp = f.q.N, where f is the gate signal frequency, q the electron charge, N the number of traps entering Icp, recently, Tsuchiya and co-workers, pointed out steps heights equal to 2.q: Pb0 centers with their donor-like and acceptor-like states in the lower and upper halves of the silicon bandgap, respectively were therefore measured for the first time in submicron devices. In the present paper, the traps remaining electrically active at the Si(100)-SiO2 interface in large area conventional MOSFETs after the full technological process including forming gas annealing are studied. This is achieved using techniques developed in recent years that use the variation of the gate signal frequency for different gate voltage swings. The trap time constant distributions that exist at this interface are studied as function of gate voltage and gate signal frequency. The results are discussed with regard to the CP models previously proposed and to CP curves simulation.
The present research letter is dedicated to a detailed analysis of a double-gate tunnel field-effect transistor (DG-TFET). The DG-TFET provides improved on-current (ION) than a conventional TFET via bandto-band (B2B) tunneling. However, DG-TFET is disadvantageous for low-power applications because of increased off-current (IOFF) due to the large ambipolar current (Iamb). In this research work, a Si/GaAs/ GaAs heterostructure DG-TFET is considered as research base for investigation of device performance. The electrical parameters of the DG-TFET device have been improved in comparison to the homostructure. The transfer (I-V) characteristics, capacitance - voltage (C-V) characteristic of homo structure Si/ Si/Si and hetero structure Si/GaAs/GaAs, DG-TFET both structures is analysed comparatively. The C-V characteristics of DG-TFET have obtained using operating frequency of 1 MHz. The ambipolar current Iamb is suppressed by 5 × 108 order of magnitude in proposed Si/GaAs/GaAs hetero DG-TFET as compared to Si/Si/Si homo DG-TFET up to the applied drain voltage very low equal to VDS = 0.5 V without affecting on- state performance. The simulation result shows a very good ION/IOFF ratio (1013) and low subthreshold slope, SS (~36.52 mV/dec). The various electrical characteristics of homo and hetero DGTFET such as on-current (ION), off - current (IOFF), time delay (ιd ), transconductance (gm) , and power delay product (PDP) have been improve in Si/GaAs/GaAs heterostructure DG-TFET and compared with Si/Si/ Si homo DG-TFET. The advantageous results obtained for the proposed design show its usability in the field of digital and analog applications.
