A 1.8-V 128-Mb mobile DRAM with double boosting pump, hybrid current sense amplifier, and dual-referenced adjustment scheme for temperature sensor

To verify three important circuit schemes suitable for DRAMs in mobile applications, a 1.8-V 128-Mb SDRAM was implemented with a 0.15-/spl mu/m technology. To achieve an ideal 33% efficiency, the double boosting pump uses two capacitor's series connection at pumping phase, while they are precharged in parallel. The hybrid folded current sense amplifier together with a novel replica inverter connection improved power and speed performances. Also, a dual-referenced adjustment scheme for a temperature sensor was proposed to allow a very high accuracy in tuning. Without loss in productivity, the implemented dual-referenced searching technique achieved tuning error of less than /spl plusmn/2.5/spl deg/C.     

35 GHz integrated circuit rectifying antenna with 33% efficiency

A 35 GHz integrated circuit rectifying antenna (rectenna) has been developed using a microstrip dipole antenna and beam-lead mixer diode. Greater than 33% conversion efficiency has been achieved. The circuit should have applications in microwave/millimetre-wave power transmission and detection.<>     

Electrical and optical properties of deep-red top-surface-emittinglasers

By studying thermal behavior of all-MBE surface-emitting lasers, barrier heights and optimum cavity design parameters are obtained. The barrier heights for holes between hetero-interfaces of Al_0.3Ga_0.7As-Al_0.65Ga_0.35As and AlAs-Al_0.65Ga_0.35As (Δx=-0.35) are measured to be 77 meV at zero bias for the deep-red top-surface-emitting laser. The barrier height decreases linearly with forward bias voltage, explaining the nonlinearity in current-voltage characteristics of the top-surface-emitting laser. The contribution of electrons to electrical resistance is estimated to be negligibly small compared to that of holes for the structure consisting of Δ_x =0.35. Minimum threshold current and maximum differential quantum efficiency observed around 200 K indicate slight mismatch between gain maximum and Fabry-Perot resonance for the deep-red top-surface-emitting laser     

Chemiluminescent and Antioxidant Micelles as Theranostic Agents for Hydrogen Peroxide Associated‐Inflammatory Diseases

Hydrogen peroxide (H₂O₂) is one of essential oxygen metabolites in living organisms, but is generated in large amounts during inflammatory responses. Therefore, H₂O₂ has great potential as diagnostic and therapeutic markers of several inflammatory and life‐threatening diseases. Here, chemiluminescent and antioxidant micelles are reported as novel theranostic agents for H₂O₂‐associated inflammatory diseases. The chemiluminescent micelles composed of amphiphilic block copolymer Pluronic F‐127, hydroxybenzyl alcohol‐incorporated copolyoxalate (HPOX) and fluorescent dyes perform peroxalate chemiluminescence reactions to detect H₂O₂ as low as 100 nM and image H₂O₂ generated in inflamed mouse ankles. The micelles encapsulating HPOX reduce the generation of reactive oxygen species in lipopolysaccharide (LPS)‐activated macrophages by scavenging overproduced H₂O₂ and releasing antioxidant hydroxybenzyl alcohol (HBA). They also exert inhibitory effects on H₂O₂‐induced apoptosis. HPOX‐based chemiluminescent and antioxidant micelles have great potential as a theranostic agent for H₂O₂‐associated inflammatory diseases.     

Ag/Ni Metallization Bilayer: A Functional Layer for Highly Efficient Polycrystalline SnSe Thermoelectric Modules

The structural and electrical characteristics of Ag/Ni bilayer metallization on polycrystalline thermoelectric SnSe were investigated. Two difficulties with thermoelectric SnSe metallization were identified for Ag and Ni single layers: Sn diffusion into the Ag metallization layer and unexpected cracks in the Ni metallization layer. The proposed Ag/Ni bilayer was prepared by hot-pressing, demonstrating successful metallization on the SnSe surface without interfacial cracks or elemental penetration into the metallization layer. Structural analysis revealed that the Ni layer reacts with SnSe, forming several crystalline phases during metallization that are beneficial for reducing contact resistance. Detailed investigation of the Ni/SnSe interface layer confirms columnar Ni-Sn intermetallic phases [(Ni₃Sn and Ni₃Sn₂) and Ni_5.63SnSe₂] that suppress Sn diffusion into the Ag layer. Electrical specific-contact resistivity (5.32 × 10^?4 Ω cm²) of the Ag/Ni bilayer requires further modification for development of high-efficiency polycrystalline SnSe thermoelectric modules.     

Soluble processed low-voltage and high efficiency blue phosphorescent organic light-emitting devices using small molecule host systems

We report low voltage driving and highly efficient blue phosphorescence organic light emitting diodes (PHOLEDs) fabricated by soluble process. A soluble small molecule mixed host system consisting of hole transporting 4,4’,4’’ tris(N-carbazolyl)triphenylamine (TCTA) and bipolar carrier transporting 2,6-bis(3-(carbazol-9-yl)phenyl)pyridine (26DCzPPy) exhibits high solubility with smooth surface properties. Moreover, this small molecule host shows the smoothest morphological property similar to a vacuum deposited amorphous film. A low driving voltage of 5.4 V at 1000 cd/m² and maximum external quantum efficiency 14.6% obtained in the solution processed blue PHOLEDs are useful for large area low cost manufacturing.     

Sensitivity analysis of ion implanted silicon wafers after rapid thermal annealing

In this study, we have investigated sensitivities of the ion implanted silicon wafers processed by rapid thermal annealing (RTA), which can reveal the variation of sheet resistance as a function of annealing temperature as well as implantation parameters. All the wafers were sequentially implanted by the arsenic or phosphorous implantations at 40, 80, and 100 keV with the dose level of 10¹⁴ to 2 × 10¹⁶ ions/cm². Rapid thermal annealing was carried out for 10 s by the infrared irradiation at a temperature between 850 and 1150°C in the nitrogen ambient. The activated wafer was characterized by the measurements of the sheet resistance and its uniformity mapping. The values of sensitivities are determined from the curve fitting of the experimental data to the fitting equation of correlation between the sheet resistance and process variables. From the sensitivity values and the deviation of sheet resistance, the optimum process conditions minimizing the effects of straggle in process parameters are obtained. As a result, a strong dependence of the sensitivity on the process variables, especially annealing temperatures and dose levels is also found. From the sensitivity analysis of the 10 s RTA process, the optimum values for the implant dose and annealing temperature are found to be in the range of 10¹⁶ ions/cm² and 1050-1100°C, respectively. The sensitivity analysis of sheet resistance will provide valuable data for accurate activation process, offering a guideline for dose monitoring and calibration of ion implantation process.     

AlxGa1−xN Ultraviolet Avalanche Photodiodes Grown on GaN Substrates

Al_xGa_1-xN (x=0.05) ultraviolet (UV) avalanche photodiodes grown on a GaN substrate are reported. The epitaxial structure was grown by metal-organic chemical vapor deposition on a free-standing bulk GaN substrate having low dislocation density. The growth conditions for Al_xGa_1-xN epitaxial layers on GaN substrates were optimized to achieve improved crystalline and structural quality. With UV illumination at lambda~250 nm, devices with mesa diameters of ~30 mum achieve stable maximum optical gains of ~50 at a reverse bias voltage of ~87 V.     

High-Performance Optical 3R Regeneration for Scalable Fiber Transmission System Applications

This paper proposes and demonstrates optical 3R regeneration techniques for high-performance and scalable 10-Gb/s transmission systems. The 3R structures rely on monolithically integrated all-active semiconductor optical amplifier-based Mach-Zehnder interferometers (SOA-MZIs) for signal reshaping and optical narrowband filtering using a Fabry-Peacuterot filter (FPF) for all-optical clock recovery. The experimental results indicate very stable operation and superior cascadability of the proposed optical 3R structure, allowing error-free and low-penalty 10-Gb/s [pseudorandom bit sequence (PRBS) 2²³-1 ] return-to-zero (RZ) transmission through a record distance of 1 250 000 km using 10 000 optical 3R stages. Clock-enhancement techniques using a SOA-MZI are then proposed to accommodate the clock performance degradations that arise from dispersion uncompensated transmission. Leveraging such clock-enhancement techniques, we experimentally demonstrate error-free 125 000-km RZ dispersion uncompensated transmission at 10 Gb/s (PRBS 2²³-1) using 1000 stages of optical 3R regenerators spaced by 125-km large-effective-area fiber spans. To evaluate the proposed optical 3R structures in a relatively realistic environment and to investigate the tradeoff between the cascadability and the spacing of the optical 3R, a fiber recirculation loop is set up with 264- and 462-km deployed fiber. The field-trial experiment achieves error-free 10-Gb/s RZ transmission using PRBS 2²³-1 through 264 000-km deployed fiber across 1000 stages of optical 3R regenerators spaced by 264-km spans     

Writing current reduction and total set resistance analysis in PRAM

We evaluated the limit of scaling bottom electrode contact (BEC) heater size and high resistivity heater to reduce writing current. It was found that the resistivity of heater should be increased for reducing writing current below the heater size of about 50 nm without any undesirable increase of resistance of the crystalline state (SET state, Rset). It was shown in the numerical simulations that the dissipated heat loss through BEC during melting GST was decreased in the increase of resistivity of heater. In addition, we analyzed the resistance components contributing to the total set resistance. It was observed that the undesired sharp increase of Rset as the BEC size decreases below 50 nm was attributed to the resistance component of GST–BEC interface. In the case of high resistivity heater, the contributions of both incomplete crystallization and heater itself were enhanced.