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In order to improve the trade-off between the 4H-SiC planar Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) and super junction MOSFET (SJ-MOSFET), particularly on the drain to source capacitance (C ds) which affects the switching performance, this study investigates the C ds of the quasi SJ-MOSFETs with various P-pillar widths, depths, and concentrations. The measured results show (1) when the N -type region between the P-pillars (Epi-1 region) is fully depleted, the C ds value abruptly drops, (2) when the N -type drift region beneath the P-pillar (Epi-2 region) is fully depleted, the slope of the C ds -V ds curve slowly changes because of the small extension of the depletion region in the P-type region. This is because the wider P-pillar width will increase the magnitude of the abrupt drop of the C ds and make the drop occur earlier; the abrupt drop of the C ds will occur later and the magnitude increases when the P-pillar depth is deeper due to the larger P-type region; Moreover, increasing the P-pillar concentration not only initiates the abrupt drop earlier and increases the magnitude, but also increases the minimum saturation value of the C ds at a higher reverse bias. This study also reveals that the mechanism of the C ds formation in a quasi SJ-MOSFET is different from the planar MOSFET and SJ-MOSFET. Finally, the simulated results are used to validate the influence of the P-pillar structures on the C ds – V ds curves in a quasi SJ-MOSFET. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.techfore.2010.03.013 Byline: Hsiao-Chun Wu (a), Hung-Yi Chen (b), Kung-Yen Lee (c) Keywords: Core technology capability; Semiconductor industry; Patent analysis; Patent grouping Abstract: Patent information provides an objective and public source to understand core technologies of companies. In this paper, a method is proposed for identifying core technology capabilities for a company in the semiconductor industry. The method is built on the patent similarity and K-means clustering algorithm. The indirect relations among the patents in the complex industry are considered in the method. In addition, the age of the patent is taken into account to avoid identifying aged core patents. The method is demonstrated by exploring the core technology capabilities that support the platform technology portfolio of the Taiwan Semiconductor Manufacturing Company (TSMC). Author Affiliation: (a) Department of Business Administration, Chaoyang University of Technology, Wufong Township Taichung County, Taiwan, ROC (b) Department of Information Management, Chaoyang University of Technology, Wufong Township Taichung County, Taiwan, ROC (c) Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei, Taiwan, ROC Article History: Received 27 July 2009; Revised 24 March 2010; Accepted 25 March 2010

The goal of this study is to investigate the performance of a small vertical-axis wind turbine at an environment with the turbulence intensity more than 30%, particularly on the influence of the vertical wind, the vertical angle, the wind with the unknown direction, the horizontal wind speed, and the turbulence intensity on the power output, which are seldom reported before. The results show that more than 90% of the power is generated when the vertical angle is less than or equal to 45°. The vertical wind speed has the obvious influence on the power when the horizontal wind speed is between 5 m/s and 8 m/s. The percentage of the power generated by the wind with the unknown direction decreases from 31.1% to 8.4% as the horizontal wind speed increases from 4 m/s to 9 m/s. The efficiency is over 40% only when the horizontal wind speed is over 8 m/s. The higher turbulence intensity increases the power at the lower wind speed, but decreases the power at the higher wind speed. Furthermore, the results can be used as a reference for the improvement of aerodynamic characteristics, efficiency, CFD simulation and the location selection of a vertical-axis wind turbine. [ABSTRACT FROM AUTHOR]

The purpose of this study is to develop a novel algorithm for a single-axis maximum power generation sun tracker in order to identify the optimal stopping angle for generating the maximum amount of daily electric energy. First, the photovoltaic modules of the single-axis maximum power generation sun tracker are automatically rotated from 50° east to 50° west. During the rotation, the instantaneous power generated at different angles is recorded and compared, meaning that the optimal angle for generating the maximum power can be determined. Once the rotation (detection) is completed, the photovoltaic modules are then rotated to the resulting angle for generating the maximum power. The photovoltaic module is rotated once per hour in an attempt to detect the maximum irradiation and overcome the impact of environmental effects such as shading from cloud cover, other photovoltaic modules and surrounding buildings. Furthermore, the detection range is halved so as to reduce the energy consumption from the rotation operations and to improve the reliability of the sun tracker. The results indicate that electric energy production is increased by 3.4% in spring and autumn, 5.4% in summer, and 8.3% in winter, compared with that of the same sun tracker with three fixed angles of 50° east in the morning, 0° at noon and 50° west in the afternoon. [ABSTRACT FROM AUTHOR]

The present study develops a hybrid PV system (HyPV) which operates at stand-alone PV mode and grid mode automatically and does not feed power into grid. HyPV operates at PV mode when solar radiation or battery energy is high enough. It switches to grid mode when battery storage is low. The switch scheme from grid to PV mode determines the system performance, including life of battery and switching device, and PV energy generation loss. A switching control parameter ( S B , critical charge energy in grid mode) is defined as function of normalized excess PV power generation ( e B ) and used in the study. A system simulation was carried out to study the effect of switching schemes on long-term system performance. A HyPV system was built and tested to exam the field performance. [ABSTRACT FROM AUTHOR]

AlGaN/GaN dual metal Schottky barrier diodes (SBD) are demonstrated on a silicon substrate. The anode is composed of two metals with different work functions to achieve a better trade-off between the forward and the reverse characteristics. The low work function metal Ti reduces the turn-on voltage and the high work function metal Ni at the edge of the anode reduces the reverse leakage current and maintains the breakdown voltage. The turn-on voltage of the Ni-SBD is reduced from 1.47 V to 0.57 V by employing the dual metal anode, and the breakdown voltages are virtually unaffected. [ABSTRACT FROM AUTHOR]