Gu et al. Nanoscale Research Letters 2011, 6:199 http://www.nanoscalereslett.com/content/6/1/199 considerable attention due to advantages such as flex- ibility, good intensity, and large area. Both indoor (tele- visions) and outdoor LED displays have been introduced to the market, and LSPR can be used to enhance the efficiency of these LEDs (mainly LEE). Meanwhile, the ability of performing light extraction from LEDs enables LSPR to be an effective top emitter (emission from the metal side instead of the substrate). In addition, utiliza- tion of LSPR obviates the need for carefully designed surface structures, thus reducing both the fabrication complexity and cost. Although a commercial display with LSPR-enhanced light extraction has not yet been made, there have been encouraging experimental results concerning the efficiency, color composition, and top emission capability, which are instrumental to the prac- tical application of LSPR-enhanced LEDs. Optoelectronic chips Digital data transport in state-of-the-art microproces- sors encompassing ultrafast transistors requires high- speed interconnects, and optical components like opti- cal fibers can satisfy the needs. Despite a capacity 1,000 times larger than their electronic counterparts, these dielectric interconnects are limited in size by the fundamental laws of diffraction to the order of wave- lengths. This means that the size must be at least one order of magnitude larger than the electronic elements, Page 9 of 12 making it rather difficult to integrate electronic and photonic devices into the same optoelectronic chip [76,77]. Surface plasmon [SP] is among the most pro- mising substitutes for optical fibers. Here, nanometer- scaled structures can serve as the SP waveguides, mod- ulators, and switches in a communication system. Si- based laser diodes are promising light sources to gen- erate SP in these optoelectronic chips because of the low cost, ease of integration into traditional integrated circuit technologies, and large-area production. How- ever, as indirect band-gap materials, the IQE of Si emitters is very low. Methods to enhance the efficiency and to increase the visible components in the Si emis- sion spectrum include the introduction of porous Si and quantum dots which have raised the IQE of Si- based light emitters to 1%. Since the report of high- efficiency visible PL from Si quantum dots in 2000 [78,79], the EL properties of Si QDs have been exten- sively investigated in an attempt to produce an all- silicon laser diode, as shown in Figure 11[80-82]. Kim et al. [42] have developed a LED structure with a Ag layer containing Ag NPs between the silicon nitride layer containing the Si QDs and Si substrate. This device yields an EL intensity that is 434% larger than that without NPs. The enhancement is attributed to the enhanced IQE, which is expected because the LSPR-induced enhancement is more substantial if the Figure 11 A future electrically driven Si laser diode with two highly reflective mirrors. The mirrors act as the optical cavity to amplify light emission. Reproduced from [79]. Copyright Nature Publishing Group, 2000.