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[en] Light-emitting CdSe quantum dot (QD) - ZnO nanorod (NR) hybrid structures were fabricated via wet chemical methods. Structural investigations indicated that the nano-sized CdSe QDs were formed on the ZnO NRs. Optical investigations showed that the energy band gap of the CdSe QDs was changed by varying the number of deposition cycles of CdSe due to the quantum confinement effect. The emissions from the hybrid structures depended on the existence of an Al2O3 shell layer on the ZnO NRs, which acted as an electrical barrier layer blocking charge carrier losses from the CdSe QDs to the ZnO NRs.
[en] In these days, demand of a LCD-TV is remarkably increasing with development of the LCD technology. However, there are thermal problems for improvement of efficiency for the LCD-TV. Thus, this research analyzed thermal problems such as convection and conduction heat transfer characteristics in the LCD-TV using an infrared (IR) camera. The results using the IR camera have been compared with those using T-type thermocouples. The results of the experiment showed that; 1. surface temperatures of inverter modules, CCFL and electrodes were higher than any other parts in the LCD-TV. 2. temperature distributions of the LCD-TV appeared asymmetrically based on the center line. 3. results of the two testing equipment agreed well.
[en] An Infra-Red camera has been used to reduce errors and to save time, cost and efforts for measurement of temperature distribution. Because allowable ranges of major factors that affect results of the measurement of the IR camera had not been established yet, this study has been performed to investigate the major factors and ranges for the effective measurement techniques. In this study, surface temperature, surrounding humidity, distance between the camera and the surface, incident angle, and emissivity of the surface have been considered as the major factors for the experimental setup. Especially, it has been observed that the results of the IR camera have been affected by the surface emissivity greatly.
[en] We report on the phase-separation of InGaN on the rough GaN surface and the fabrication of the light-emitting diode (LED) using a phase-separated InGaN layer as an active layer. Atomic force microscopy (AFM) images of GaN surfaces showed that the roughness of GaN surfaces was increased by supplying trimethyl gallium source during the ramping down time of the temperature. Photoluminescence (PL) spectra and cathodoluminescence (CL) images showed that the phase-separation of InGaN was enhanced on the rough GaN surface due to the difference of surface mobility of Ga and In. An LED was fabricated by inserting the phase-separated InGaN layer between p-type and n-type GaN. The PL spectrum exhibited separated peaks at high and low energy side, but the electroluminescence (EL) spectrum revealed a broad EL peak centered at low energy side at a low injection current. The EL peak was shifted to high energy side with an increase of the input current. These observations were attributed to the different depths of the potential wells of InGaN phases with different indium compositions caused by phase-separation. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)