Effects of contact electrode size on the characteristics of polycrystalline-Si p-i-n solar cells

The effects of contact electrode size on the photo-voltaic characteristics of polycrystalline-Si p-i-n solar cells have been studied,with respect to a unit-cell pitch size of 1μm width.For the non-transparent Al contact electrode with a contact width of 0.05-0.2μm,the short-circuit current is obviously reduced with increasing contact width,due to a larger area of optical reflection by the electrode.On the other hand,even when using a transparent ITO(indium-tin-oxide) electrode,a larger width of contact e...     

Conductive adhesive with transient liquid‐phase sintering technology for high‐power device applications

A highly reliable conductive adhesive obtained by transient liquid‐phase sintering (TLPS) technologies is studied for use in high‐power device packaging. TLPS involves the low‐temperature reaction of a low‐melting metal or alloy with a high‐melting metal or alloy to form a reacted metal matrix. For a TLPS material (consisting of Ag‐coated Cu, a Sn96.5‐Ag3.0‐Cu0.5 solder, and a volatile fluxing resin) used herein, the melting temperature of the metal matrix exceeds the bonding temperature. After bonding of the TLPS material, a unique melting peak of TLPS is observed at 356 °C, consistent with the transient behavior of Ag₃Sn + Cu₆Sn₅ → liquid + Cu₃Sn reported by the National Institute of Standards and Technology. The TLPS material shows superior thermal conductivity as compared with other commercially available Ag pastes under the same specimen preparation conditions. In conclusion, the TLPS material can be a promising candidate for a highly reliable conductive adhesive in power device packaging because remelting of the SAC305 solder, which is widely used in conventional power modules, is not observed.     

A high efficiency transmitter and receiver for magnetic resonant wireless battery charging system in 0.35 μm BCD

This paper presents a transmitter and receiver for magnetic resonant wireless battery charging system. In the receiver, a wide-input range CMOS multi-mode active rectifier is proposed for a magnetic resonant wireless battery charging system. The configuration is automatically changed with respect to the magnitude of the input AC voltage. The output voltage of the multi-mode rectifier is sensed by a comparator. Furthermore, the configuration of the multi-mode rectifier is automatically selected by switches as original rectifier mode, 1-stage voltage multiplier or 2-stage voltage multiplier mode. As a result, a rectified DC voltage is output from 7.5 to 19 V for an input AC voltage of 5–20 V. In the transmitter, a class-E power amplifier (PA) with an automatic power control loop and load compensation circuit is proposed to improve the power efficiency. The transmitted power is controlled by adjusting the signal applied to the gate of the power control transistor. In addition, a parallel capacitor is also controlled to enhance the efficiency and compensate for the load variation. This chip is implemented using 0.35 μm BCD technology with an active area of around 5,000 × 2,500 μm. When the magnitude of the input AC voltage is 10 V, the power conversion efficiency of the multi-mode active rectifier is about 94 %.The maximum power efficiency of the receiver is about 70 %. The transmitter provides an output power control range of 10–30.2 dBm. The maximum power efficiency of the PA is 71.5 %.     

Simultaneous Static Testing of A/D and D/A Converters Using a Built‐in Structure

Static testing of analog‐to‐digital (A/D) and digital‐to‐analog (D/A) converters becomes more difficult when they are embedded in a system on chip. Built‐in self‐test (BIST) reduces the need for external support for testing. This paper proposes a new static BIST structure for testing both A/D and D/A converters. By sharing test circuitry, the proposed BIST reduces the hardware overhead. Furthermore, test time can also be reduced using the simultaneous test strategy of the proposed BIST. The proposed method can be applied in various A/D and D/A converter resolutions and analog signal swing ranges. Simulation results are presented to validate the proposed method by showing how linearity errors are detected in different situations.     

Biomimetic Chitin–Silk Hybrids: An Optically Transparent Structural Platform for Wearable Devices and Advanced Electronics

The cuticles of insects and marine crustaceans are fascinating models for man‐made advanced functional composites. The excellent mechanical properties of these biological structures rest on the exquisite self‐assembly of natural ingredients, such as biominerals, polysaccharides, and proteins. Among them, the two commonly found building blocks in the model biocomposites are chitin nanofibers and silk‐like proteins with β‐sheet structure. Despite being wholly organic, the chitinous protein complex plays a key role for the biocomposites by contributing to the overall mechanical robustness and structural integrity. Moreover, the chitinous protein complex alone without biominerals is optically transparent (e.g., dragonfly wings), thereby making it a brilliant model material system for engineering applications where optical transparency is essentially required. Here, inspired by the chitinous protein complex of arthropods cuticles, an optically transparent biomimetic composite that hybridizes chitin nanofibers and silk fibroin (β‐sheet) is introduced, and its potential as a biocompatible structural platform for emerging wearable devices (e.g., smart contact lenses) and advanced displays (e.g., transparent plastic cover window) is demonstrated.     

Defect Restoration of Low‐Temperature Sol‐Gel‐Derived ZnO via Sulfur Doping for Advancing Polymeric Schottky Photodiodes

This study shows that the deep‐level defect states in sol‐gel‐derived ZnO can be efficiently restored by facile sulfur doping chemistry, wherein the +2 charged oxygen vacancies are filled with the S^2? ions brought by thiocyanate. By fabricating a solution‐processed polymeric Schottky diode with ITO/ZnO as the cathode, the synergetic effects of such defect‐restored ZnO electron selective layers are demonstrated. The decreased chemical defects and thus reduced mid‐gap states enable to not only enlarge the effective built‐in potential, which can expand the width of the depletion region, but also increase the Schottky energy barrier, which can reduce undesired dark‐current injection. As a result, the demonstrated simple‐structure blue‐selective polymeric Schottky photodiode renders near‐ideal diode operation with an ideality factor of 1.18, a noise equivalent power of 1.25 × 10^?14 W Hz^?1/2, and a high peak detectivity of 2.4 × 10¹³ Jones. In addition, the chemical robustness of sulfur‐doped ZnO enables exceptional device stability against air exposure as well as device‐to‐device reproducibility. Therefore, this work opens the possibility of utilizing low‐temperature sol‐gel‐derived ZnO in realizing high‐performance, stable, and reliable organic photodiodes that could be employed in the design of practical image sensors.     

Outage Probability Analysis for Energy Harvesting Cooperative Relays in a Clustered Environment

This paper presents the outage probability analysis of the energy harvesting (EH) decode and forward (DF) cooperative relay network when more than one relays are available to assist the communication between source and destination in the presence of the direct connection. The relays use power splitting (PS) protocol with adaptive PS ratio for EH. As wireless EH can be more beneficial over smaller distances therefore a clustered environment is considered in which the source, destination and relays are located in a small area. First, we analyze the performance of selection cooperation (SC) which requires channel state information (CSI) at the source. High signal to noise ratio approximation of the outage probability is provided for this case. Secondly, we present the performance of all relays cooperation (ARC) scheme which requires no CSI at the source. Lower and upper bounds of the outage probability are presented for smaller number of relays in ARC scheme whereas high signal to noise ratio approximation is provided for higher number of relays. Simulation results validate the analytical results and show that SC scheme outperforms ARC scheme at the expense of CSI requirement.     

Compact LDD nMOSFET degradation model

In this paper, we present a compact degraded I-V model for submicron lightly-doped drain (LDD) MOSFET's. The analytical and physics-based model was developed using the drift equation and considering the nonuniform spatial hot-carrier-induced interface states and the detailed LDD structure. It can be used to calculate fresh channel electric field and drain current by turning off the effect of hot-carrier-induced interface states. Using the fresh electric field in conjunction with a simplified energy balance equation, the nonuniform spatial distribution of induced interface states ran be calculated. By incorporating this distribution into the degraded current model, we can describe the damaged I-V characteristics and channel electric fields as a function of stress time. The model includes the effects of series resistances and carrier velocity saturation. It can be used to calculate time-dependent degraded drain current, and is a time-saving CAD model     

Effect of nonlinear modal interaction on control performance: useof normal forms technique in control design. II. Case studies

This is part II of a two part paper dealing with control design in power systems using the normal forms technique. The companion paper (part I) describes the general theory and control procedure. Also, the proposed procedure was applied to the Base Case of the 50-generator IEEE Test System. This paper depicts the case studies to show the validation of the proposed method and to observe the effects of controller setting changes. In addition the results dealing with the design of the controller are given and verification of the controller design using nonlinear time simulation is provided     

Hot-carrier-induced photovoltage in silicon bipolar junction transistors

As bipolar junction transistors (BJTs) are scaled down, the current density increases and base pushout may happen. To prevent base widening, the collector doping concentration is increased; therefore, this increases the electric field in the base-collector junction. In the active operation of BJTs, impact ionization happens and impact-ionization-induced photon emission is created in the base-collector (BC) junction and photon absorption happens in the base-emitter (BE) junction. This makes the carrier injection from the BE junction to the BC junction with avalanche different from that without avalanche. Similarly, the avalanche-induced light emission in the BE junction will induce photocarriers in the BC junction diode. In this paper, we report observation of the photovoltage in the BC junction resulting from hot-carrier electroluminence in the BE junction on a conventional low-power n-p-n bipolar transistor. We found a photovoltage of 0.36 V and a collector current reversal in the inverse active operation.