Investigation of 4H-SiC MOS capacitors annealed in diluted N2O at different temperatures

Thermally grown oxide on 4H-SiC has been post-annealed in diluted N₂O (10% N₂O in N₂) at different temperatures from 900 to 1100 °C. The quality of the nitrided oxide and the SiO₂/4H-SiC interface was investigated by AC conductance and high frequency C-V measurements based on Al/SiO₂/4H-SiC metal-insulator-semiconductor (MOS) structure. It is found that N₂O annealing at 1000 °C produces the lowest interface state density, though the difference is not so significant when compared to the other samples annealed at 900 and 1100 °C. These results can be explained by the high temperature dynamic decomposition process of N₂O. By fitting the AC conductance data, it is found that higher temperature nitridation increases the capture cross-section of the interface traps.     

An Intelligent Product Recommendation Model to Reflect the Recent Purchasing Patterns of Customers

Mobile Networks and Applications - This study suggests a new product recommendation model to reflect the recent purchasing patterns of customers. There are many methods to measure the similarity...     

A vertically periodic defected ground structure and its application in reducing the size of microwave circuits

The microstrip and coplanar waveguide transmission lines combined by a vertically periodic defected ground structure (VPDGS) are proposed. The slow-wave effect, equivalent circuit, and the performances are shown. As an application example, VPDGS is adopted in the matching networks of an amplifier for size-reduction. Two series microstrip lines in input and output matching networks of the amplifier are reduced to 38.5% and 44.4% of the original lengths, respectively, due to the increased slow-wave effects, while the amplifier performances are preserved.     

A 0.5-8.5 GHz fully differential CMOS distributed amplifier

A fully integrated fully differential distributed amplifier with 5.5 dB pass-band gain and 8.5 GHz unity-gain bandwidth is described. The fully differential CMOS circuit topology yields wider bandwidth than its single-ended counterpart, by eliminating the source degeneration effects of parasitic interconnect, bond wire, and package inductors. A simulated annealing CAD tool underpins the parasitic-aware methodology used to optimize the design including all on-chip active and passive device and off-chip package parasitics. Mixed-mode S-parameter measurement techniques used for fully differential circuit testing are reviewed. Integrated in 1.3/spl times/2.2 mm/sup 2/ in a standard 0.6 /spl mu/m CMOS process, the distributed amplifier dissipates 216 mW from a single 3 V supply.     

Fast full search motion estimation algorithm using early detection of impossible candidate vectors

To reduce the amount of computations for a full search (FS) algorithm for fast motion estimation, we propose a new and fast FS motion estimation algorithm. The computational reduction of our FS motion estimation algorithm comes from fast elimination of impossible motion vectors. We obtain faster elimination of inappropriate motion vectors using efficient matching units from localization of a complex area in image data. In this paper, we show three properties in block matching of motion estimation. We suggest two fast matching scan algorithms: one from adaptive matching scan and the other from fixed dithering order. Experimentally, we remove the unnecessary computations by about 30% with our proposed algorithm compared with the conventional fast FS algorithms.     

Improved HBT linearity with a "post-distortion"-type collector linearizer

An HBT amplifier with a "post-distortion"-type linearizer utilizing a base-collector junction diode shows more than 8-dB improvement of adjacent channel power ratio, and the collector linearizer comprising a reverse biased base-collector junction diode requires no additional dc power consumption and has no deterioration of RF performance. The linearization technique of post-distortion compensates the nonlinearity of HBTs, which arises from the C/sub bc/ variation due to a large-signal swing.     

Perpendicularly Aligned,Size‐and Spacing‐Controlled Nanocylinders by Molecular‐Weight Adjustment of a Homopolymer Blended in an Asymmetric Triblock Copolymer

Perpendicularly arrayed and size‐controlled nanocylinders have been prepared by simply blending an asymmetric polystyrene‐block‐polyisoprene‐block‐polystyrene triblock copolymer with polystyrene (the minority component) homopolymers of different molecular weights. The preference for perpendicular orientation or hexagonal ordering of the nanocylinders over a large area in the asymmetric block copolymer can be controlled by adjusting the molecular weight of the blended homopolymer, and the perfection of hexagonal ordering of the perpendicular cylinders can be tuned by using a substrate whose surface tension is much different from that of the majority component of the block copolymer. Such highly controlled nanostructured block‐copolymer materials, which have been obtained by a simple method independent of film thickness and interfacial tension between the blocks and the substrates, have wide‐ranging commercial potential, e.g., for use in membranes and nanotemplates with size‐tunable pores, bandgap‐controlled photonic crystals, and other nanotechnological fields demanding a specific nanosize and nanomorphology.     

Improvement of the cell performance in the ZnS/Cu(In,Ga)Se2 solar cells by the sputter deposition of a bilayer ZnO : Al film

ZnS is a candidate to replace CdS as the buffer layer in Cu(In,Ga)Se₂ (CIGS) solar cells for Cd‐free commercial product. However, the resistance of ZnS is too large, and the photoconductivity is too small. Therefore, the thickness of the ZnS should be as thin as possible. However, a CIGS solar cell with a very thin ZnS buffer layer is vulnerable to the sputtering power of the ZnO : Al window layer deposition because of plasma damage. To improve the efficiency of CIGS solar cells with a chemical‐bath‐deposited ZnS buffer layer, the effect of the plasma damage by the sputter deposition of the ZnO : Al window layer should be understood. We have found that the efficiency of a CIGS solar cell consistently decreases with an increase in the sputtering power for the ZnO : Al window layer deposition onto the ZnS buffer layer because of plasma damage. To protect the ZnS/CIGS interface, a bilayer ZnO : Al film was developed. It consists of a 50‐nm‐thick ZnO : Al plasma protection layer deposited at a sputtering power of 50 W and a 100‐nm‐thick ZnO : Al conducting layer deposited at a sputtering power of 200 W. The introduction of a 50‐nm‐thick ZnO : Al layer deposited at 50 W prevented plasma damage by sputtering, resulting in a high open‐circuit voltage, a large fill factor, and shunt resistance. The ZnS/CIGS solar cell with the bilayer ZnO : Al film yielded a cell efficiency of 14.68%. Therefore, the application of bilayer ZnO : Al film to the window layer is suitable for CIGS solar cells with a ZnS buffer layer. Copyright © 2012 John Wiley & Sons, Ltd.     

A novel hybrid silica wide-band amplifier covering S+C+L bands with 105-nm bandwidth

We report a novel hybrid optical amplifier covering S+C+L bands with 105-nm total bandwidth using a silica fiber. The principle of amplification is based on the stimulated radiative transition of Er-ions for C-band and on the stimulated Raman scattering for S- and L-band, respectively. In this letter, we analyze the amplification characteristics for two types of active fiber mediums through numerical simulation. One is a silica fiber configured with Er-doped cladding and Ge-doped core and the other is a medium consisting of Er-doped fiber and dispersion-compensating fiber. By optimizing parameters such as fiber length and pump power, we newly achieve wide-band amplification with 105-nm bandwidth showing a flat gain characteristic over the entire S+C+L bands.     

A Framework for MPEG‐4 Contents Delivery over DMB

Digital Multimedia Broadcasting (DMB) is an upcoming standard in Korea used to provide mobile multimedia broadcasting service based on the Eureka‐147 Digital Audio Broadcasting (DAB) system. The current dominant multimedia coding standard, MPEG‐4, is foreseen to play an important role in forthcoming DMB services. However, the current approaches for transporting MPEG‐4 content over DMB networks are not optimized. To address this issue we propose a novel MPEG‐4 stream multiplexer, called M4SMux, which provides better stream multiplexing and delivery over DMB networks. M4SMux features an MPEG‐4 elementary‐stream interleaving mechanism that reduces the multiplexing overhead and a multiplex configuration mechanism that utilizes M4SLinkTable for easy content access. In addition, we propose an error correction method which enhances transport efficiency.