Papers by Keyword: UV-LED

Abstract: Ultraviolet light emitting diodes(UV-LEDs)presenting the advantages of high efficiency,small size,energy saving and without mercury,are gradually replacing mercury lamps in disinfection systems.This study focused 280nm wavelength of UV-LEDs,the Escherichia coli was served as objective in wastewater,the inactivation efficiency and photoreactivation percentage were examined compared with traditional mercury lamps.A series of UV-LEDs dose caused different inactivationefficiency and photoreactivation percentage of E.coli.When UV dose was 1.8 mJ/cm2, inactivation efficiency reached 2.7-lg,then under a 40w sunlight lamp irradiation,the photoreactivation percentage was up to 2.7%;at 3.6 mJ/cm2, inactivation efficiency reached 3-lg,photoreactivation percentage was up to 0.98%.In advanced wastewater treatment,a threshold dose 3.6 mJ/cm2 is suggested of 280nm UV-LEDS.UV dose higher than 3.6 mJ/cm2 can achieve the depth of sterilization effect,that reaches the effect of mercury lamp 40mJ/cm2.The results indicate great advantages of UV-LEDs compared with mercury lamps.

Abstract: Fluorescence is widely used to detect the biochemical effect and some substance containing certain dye. In general, the formation of fluorescent reaction is that an organism or dye, excited by UV light, emits a specific frequency of light; the light is usually a visible or near infrared light. Practically, the fluorescence of object can be excited by continued UV light, but the contrast and sharpness of fluorescence image decrease readily with stray light from the surrounding. In this study, we connect a trigger LED light module to a portable camera system and to perform the fluorescence inspection. When the fluorescent object is excited by asynchronous trigger UV-LED light, the extra intensity of fluorescence can be obtained. In the experiment of security organic dye (BL-ORT), the relative intensity of fluorescence acquired by 30 fps CCD can be increased by more than 11 %. In addition, when the fluorescent dye (chlorine e6) is injected into the tail vein of nude mouse, if its tail excited by the 375nm asynchronous trigger and continuous UV-LED are processed, the average relative intensity is 56.5 % and 49 %, respectively. Therefore, an added relative fluorescence of 15.3 % can be obtained from asynchronous triggering method. Furthermore, the ratio of extra intensity increases with the increase of frame rate of camera.

Abstract: Direct light triggering of 4H-SiC thyristors with a 365 nm UV LED was demonstrated. Two different structures with etched and non etched gate were successfully tested. The current rise time was less than 100 ns and the delay time as short as 1.5 μs. The optical energy density necessary to switch-on a thyristor has been studied for different optical power densities and bus voltages. This work shows that the UV LED technology is becoming sufficiently powerful to switch-on SiC thyristors. Thus, an alternative, less expensive and more compact gate light source than UV laser is now possible. This can be of particular interest for very high voltage and pulse power electronic applications.

Abstract: The fundamental growth issues of AlN and AlGaN on sapphire and SiC using metalorganic vapor phase epitaxy, particularly the growth of AlN and AlGaN on a groove-patterned template are reviewed. In addition, the conductivity control of AlGaN is shown. The conductivity control of p-type AlGaN, particularly the realization of a high hole concentration, is essential for realizing high-efficiency UV and DUV LEDs and LDs.