Developments on Perovskite Solar Cells (PSCs): A Critical Review

This review provides detailed information on perovskite solar cell device background and monitors stepwise scientific efforts applied to improve device performance with time. The work reviews previous studies and the latest developments in the perovskite crystal structure, electronic structure, device architecture, fabrication methods, and challenges. Advantages, such as easy bandgap tunability, low charge recombination rates, and low fabrication cost, are among the topics discussed. Some of the most important elements highlighted in this review are concerns regarding commercialization and prototyping. Perovskite solar cells are generally still lab-based devices suffering from drawbacks such as device intrinsic and extrinsic instabilities and rising environmental concerns due to the use of the toxic inorganic lead (Pb) element in the perovskite (ABX3) light-active material. Some interesting recommendations and possible future perspectives are well articulated.

Analysis of electrical characteristics and electroluminescent efficiency of field induced contact-DGOLET

This research paper discusses the significance development in field-induced contact dual-gate organic light emitting transistor (FIC-DGOLET) device architecture and characteristics. The device behaviour is analyzed and observed significant value of electroluminescent efficiency. The deep investigation of FIC-DGOLET device is discussed in this paper, where impact of varying the various parameters such as thickness of organic semiconductor (OSC) materials from the range of 400 nm to 200 nm at altered value of threshold voltage by using 2D ATLAS simulator. Its theoretical calculation influence over the dynamic control of the device characteristics such as saturated drain current (I ds ), mobility (μ), threshold voltage (V th ) as well as sub threshold swing. The FIC-DGOLET is a dual-gate transistor which also emits light by the operations of two accumulated regions, that are electrons and holes which is not completely overlapped to each other. The leakage current in DG-OLET can be reduced to the extent that 70% than single gate OLET (SG-OLET). The recombination zone mechanism of FIC-DGOLET plays a vital role in its performance, where we get comparable value of electroluminescent efficiency with reported, low value of exciton quenching and current densities. The extracted parameters of DG-OLETs are like drive current of 100A, I on/off 108, threshold voltage V th of 1.3 V at V gs of –3 V and V ds of 0 to –3 V. These extracted performance parameters are very helpful in designing of flexible display applications.

Automated Measurement and Analysis of Sidewall Roughness (SWR) Using 3D-AFM

As the semiconductor device architecture develops, from planar field-effect transistor (FET) to FinFET and toward gate all around (GAA), it is more needed to measure 3D structure sidewall precisely. Here, we present a 3D-atomic force microscopy (3D-AFM) by Park Systems Corp., a powerful 3D metrology tool to measure SWR of vertical and undercut structures. First, we measured 3 different dies repeatedly to calculate reproducibility in die level. Reproducible results were derived with relative standard deviation under 2%. Second, we measured 13 different dies, including the center and edge of the wafer, to analyze SWR distribution in wafer level and reliable results were measured. And all analysis was performed using a novel algorithm including auto flattening, sidewall detection, and SWR calculation. In addition, SWR automatic analysis software was implemented to reduce analysis time and to provide standard analysis. The result suggests that our 3D-AFM based on tilted Z scanner enabled an advanced methodology for automated 3D measurement and analysis.

Characterization of electrostatically defined bottom-heated InAs nanowire quantum dot systems

Conversion of temperature gradients to charge currents in quantum dot systems enables probing various concepts from highly efficient energy harvesting and fundamental thermodynamics to spectroscopic possibilities complementary to conventional bias device characterization. In this work, we present a proof-of-concept study of a device architecture where bottom-gates are capacitively coupled to an InAs nanowire and double function as local joule heaters. The device design combines the ability to heat locally at different locations on the device with the electrostatic definition of various quantum dot and barrier configurations. We demonstrate the versatility of this combined gating- and heating approach by studying, as a function of the heater location and bias, the Seebeck effect across the barrier-free nanowire, fit thermocurrents through quantum dots for thermometry and detect the phonon energy using a serial double quantum dot. The results indicate symmetric heating effects when the device is heated with different gates and we present detection schemes for the electronic and phononic heat transfer contribution across the nanowire. Based on this proof-of-principle work, we propose a variety of future experiments.

Transcatheter Closure of Atrial Septal Defect

Background: Over the past decade, percutaneous atrial septal defect (ASD) closure has been the preferred treatment option in many clinical programs for ASD. Percutaneous ASD closures with advanced device architecture and distribution have established user experience and process security. The ability to diagnose has also improved. The devices have evolved from the larger fixtures to the reset zone, being easily eliminated with little residual mesh material and comfortable fitting with the surrounding structures. Biodegradable technology has been introduced and will be considered as a future option. The emergence of the use of the ASD closure device over the last forty years includes improvements that reduce the incidence of adverse effects reported over the years. Issues reported in the literature include thrombus formation, air tightness, device insertion, abrasion, residual shunts and nickel hypersensitivity. Modern tools hold medium and long-term data with excellent results. Multi-sized devices securely close simple and complex ASDs that can re-scan, reset, and detect percutaneous advanced delivery procedures. In this review, the most widely used tools and distribution processes are discussed and the tools that show promise for the future. Conclusion: As the field of transcatheter treatment of atrial septal defects (TC-ASD) and congenital interventional cardiology develops, real-world design studies provide valuable developmental information on aspects of care where there is disagreement about best practices and more research is needed.

High-responsivity photodetector based on scrolling monolayer MoS2 hybridized with carbon quantum dots.

The monolayer MoS2 based photodetectors have been widely investigated, which show limited photoelectric performances due to its low light absorption and uncontrollable adsorbates. In this paper, we present a MoS2-based hybrid nanoscrolls device, in which one-dimensional nanoscrollsof MoS2 is hybridized with carbon quantum dots (CQDs). This device architecture effectively enhanced the photodetection performance. The photoresponsivity and detectivity values of MoS2/CQDs-NS photodetectors are respectively 1793 A W-1 and 5.97×1012 Jones, which are 830-fold and 268-fold higher than those of pristine MoS2 under 300 nm illumination at Vds = 5 V. This research indicates a significant progress in fabricating high-performance MoS2 photodetectors.

Artificial Intelligence Enhancements in the field of Functional Verification

Functional Verification is one of the main processes in the Research and Development of new System-on-Chip. As chips are becoming more and more complex, this step becomes an extensive bottleneck which can vastly delay the chip mass production. It is a mandatory step as the design needs to not contain any faults, to ensure proper functioning. If this step is bypassed, large major financial losses and customer dissatisfaction can happen later in the process. Additionally, if the verification process is prolonging for a long period of time, to achieve a higher quality product, it will also cause a financial impact. Therefore, the solution is to find ways to optimize this activity. This paper contains a review on how Artificial Intelligence can reduce this blockage, taking into consideration the time spent on implementing the verification environment and the time of attaining the aimed coverage percentage. The engineer will take a decision on which causes of time-consuming processes presented in the paper will be reduced, depending on project specifics and his or her experience. A candidate for optimizing the training of the Neural Network is the Nvidia’s Computer Unified Device Architecture (CUDA). CUDA is parallel computing platform that make use of the GPU, peculiarly of the CUDA cores located inside Nvidia GPUs.

N,N′-bis(3-methylphenyl)-N,N′-dyphenylbenzidine Based Distributed Feedback Lasers with Holographically Fabricated Polymeric Resonators

The molecule N,N′-bis(3-methylphenyl)-N,N′-dyphenylbenzidine (TPD) has been widely used in optoelectronic applications, mainly for its hole-transporting properties, but also for its capability to emit blue light and amplified spontaneous emission, which is important for the development of organic lasers. Here, we report deep-blue-emitting distributed feedback (DFB) lasers based on TPD dispersed in polystyrene (PS), as active media, and dichromated gelatin layers with holographically engraved relief gratings, as laser resonators. The effect of the device architecture (with the resonator located below or on top of the active layer) is investigated with a dye (TPD) that can be doped into PS at higher rates (up to 60 wt%), than with previously used dyes (<5 wt%). This has enabled changing the index contrast between film and resonator, which has an important effect on the laser performance. With regards to thresholds, both architectures behave similarly for TPD concentrations above 20 wt%, while for lower concentrations, top-layer resonator devices show lower values (around half). Remarkably, the operational durability of top-layer resonator devices is larger (in a factor of around 2), independently of the TPD concentration. This is a consequence of the protection offered by the resonator against dye photo-oxidation when the device is illuminated with pulsed UV light.