We present a design of plasmonic cavities that consists of two sets of 1-D plasmonic crystal reflectors on a plasmonic trench waveguide. A 'reverse image mold' (RIM) technique was developed to pattern high-resolution silver trenches and to embed emitters at the cavity field maximum, and FDTD simulations were performed to analyze the frequency response of the fabricated devices. Distinct cavity modes were observed from the photoluminescence spectra of the organic dye embedded within these cavities. The cavity geometry facilitates tuning of the modes through a change in cavity dimensions. Both the design and the fabrication technique presented could be extended to making trench waveguide-based plasmonic devices and circuits. "Quantum nature of a strongly coupled single quantum dot-cavity system," Nature 445(7130), 896-899 (2007). 4. S. Kühn, U. Håkanson, L. Rogobete, and V. Sandoghdar, "Enhancement of single-molecule fluorescence using a gold nanoparticle as an optical nanoantenna," Phys. between surface plasmon-polaritons and organic molecules in subwavelength hole arrays," Phys. Rev. B 71(3), 035424 (2005). 9. P. Anger, P. Bharadwaj, and L. Novotny, "Enhancement and quenching of single-molecule fluorescence," Phys.

We observed a 32-fold increase in the spontaneous emission rate of InGaN/GaN quantum well ͑QW͒ at 440 nm by employing surface plasmons ͑SPs͒ probed by time-resolved photoluminescence spectroscopy. We explore this remarkable enhancement of the emission rates and intensities resulting from the efficient energy transfer from electron-hole pair recombination in the QW to electron vibrations of SPs at the metal-coated surface of the semiconductor heterostructure. This QW-SP coupling is expected to lead to a new class of super bright and high-speed light-emitting diodes ͑LEDs͒ that offer realistic alternatives to conventional fluorescent tubes. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.2010602͔Currently, InGaN-GaN quantum well ͑QW͒ based lightemitting diodes ͑LEDs͒ have been developed and expected to eventually replace more traditional fluorescent tubes as illumination sources. 1,2 However, the emission efficacy of commercial white LEDs is still substantially lower than that of fluorescent tubes. 3 Recently, we have reported a method for enhancing the light emission efficiency from InGaN QWs by controlling the energy transfer between QW emitters and surface plasmons ͑SPs͒. 4 The idea of SP enhanced light emission was previously described 5-15 and efficient SPenhanced visible light emission has been demonstrated. 4 Moreover, the enhancement of an emission rate is also very important for the development of communication technology and optical computing. However, spontaneous emission rates of InGaN-GaN QWs are usually reduced by the carrier localization effect 16,17 and the quantum confinement Stark effect, 18,19 and very difficult to enhance. There are only a few reports on the enhancement of the emission rates by reducing the piezo-electric field 20 and making photonic crystal structure. 21 We believe that our developed SP coupling technique has the potential to enhance the spontaneous emission rate dramatically. 4 Since the density of states of SP mode is much larger, the QW-SP coupling rate should be very fast, and this new path of a recombination can increase the spontaneous emission rate. However, clear evidence for fast rate of QW-SP coupling has not so far been reported on the SP enhanced emission. We investigate the direct observation of SP coupled spontaneous emission rate by using the timeresolved photoluminescence ͑PL͒ measurements here. Moreover, we consider the mechanisms and dynamics of energy transfer and light extraction. This study should also be very useful for further optimization of the QW-SP coupling condition and for designing even more efficient device structures.InGaN-GaN QW wafers were grown on 0001 oriented sapphire substrates by metal-organic chemical vapor deposition ͑MOCVD͒. The grown structures consist of a GaN ͑4 m͒ buffer layer, an InGaN SQW ͑3 nm͒ followed by a GaN cap layer ͑10 nm͒. A 50 nm thick silver layer was then evaporated on top of the wafer surface. To perform timeresolved PL measurements, the frequency doubled output from a mode-locked Ti: Al 2 O 3 laser was used to...

We markedly improved the extraction efficiency of emission light from the InGaN-based light-emitting diode (LED) chips grown on sapphire substrates. Two new techniques were adopted in the fabrication of these LEDs. One is to grow nitride films on the patterned sapphire substrate (PSS) in order to scatter emission light. Another is to use the Rh mesh electrode for p-GaN contact instead of Ni/Au translucent electrode in order to reduce the optical absorption by the p-contact electrode. We fabricated near-ultraviolet (n-UV) and blue LEDs using the above-mentioned techniques. When the n-UV (400 nm) LED was operated at a forward current of 20 mA at room temperature, the output power and the external quantum efficiency were estimated to be 22.0 mW and 35.5%, respectively. When the blue (460 nm) LED was operated at a forward current of 20 mA at room temperature, the output power and the external quantum efficiency were estimated to be 18.8 mW and 34.9%, respectively.

We fabricated a phosphor-conversion white light emitting diode (LED) using an InGaN chip that emits 400 nm near-ultraviolet (n-UV) light and phosphors that emit in the blue and yellow region. When the white LED was operated at a forward-bias current of 20 mA at room temperature (RT), the color temperature (T cp ), average color rendering (R a ), operating voltage (V f ) and luminous efficacy (η L ) were estimated to be 5800 K, 85.3, 3.2 V, and 26.1 lm/W, respectively. With increasing forward-bias current, the luminous flux increased almost linearly and was estimated to be 5.0 lm at 60 mA. The Commission Internationale de l'Eclairage (CIE) chromaticity coordinates obtained from the measured spectra remained almost constant during the forwardbias current increase from 0.5 mA to 60 mA.