papers C. M. Lieber et al Nanowires for Integrated Multicolor Nanophotonics*r s Nanophoto Yu Huang Xiangfeng Duan, and Charles M. Lieber Nanoscale light-emitting diodes(nano LEDs)with colors spanning from the ultraviolet to near-infrared region of the electromagnetic spectrum Keywords: were prepared using a solution-based approach in which emissive electroluminescence sive hole-doped silicon nanowires in a crossed nanowire architecture electron-doped semiconductor nanowires were assembled with none optoelectronics Single- and multicolor nanoled devices and arrays were made with photonics colors specified in a predictable way by the bandgaps of the Ill-v and II-VI nanowire building blocks. The approach was extended to combine nanoscale electronic and photonic devices into integrated structures where a nanoscale transistor was used to switch the nanoled on and off. In addition, this approach was generalized to hybrid devices consist ing of nanowire emitters assembled on lithographically patterned planar silicon structures, which could provide a route for integrating photonic devices with conventional silicon microelectronics. Lastly, nano LEDs were used to optically excite emissive molecules and nanoclusters, and hence could enable a range of integrated sensor/detection "chips"with multiplexed analysis capabilities. Bottom-up assembly of nanoscale building blocks into in- NW logic gates, &9 and in nanophotonics with the assembly creasingly complex structures offers the potential to produce of, for example, individual light-emitting diodes 5, oand devices with novel function since it is possible to combine laser diodes l1 a general way materials with distinct chemical composition, The assembly of chemically distinct nanoscale building structure, size, and morphology, in contrast to planar device blocks that would otherwise be structurally and/or chemical fabricationI-31 Semiconductor nanowires (NWs)o and ly incompatible in a sequential growth process typical of carbon nanotubes I are especially attractive building blocks planar fabrication has received considerably less attention. for assembling active and integrated nanosystems since the However, this capability of the bottom-up approach should individual nanostructures can function as both device ele- allow for assembly of nanostructures with function not read- ments and interconnects. This concept has been demonstrat- ily obtained by other methods and open new opportunities ed in nanoelectronics with the assembly of a variety of devi- For example, planar silicon, which serves as the foundation es, such as field-effect transistors(FETs)4-7 and integrated for the microelectronics industry, is poorly suited to many photonic applications since it has a poor efficiency for light emission. 2 Here we demonstrate the assembly of a wide Department of Chemistry and Chemical Biology, Division of Engi- nge of efficient direct-gap III-V and II-VI NWs with sili I Dr Y Huang, Dr X. Duan, Prof C M. Lieber con NWs(SiNWs) and planar silicon structures to produce neering and Applied Science multicolor, electrically driven nanophotonic and integrated Harvard University Cambridge, Massachusetts 02138(USA) nanoelectronic-photonic systems. The flexibility of our ap- E-mail: cml@cmliris. harvard. edu proach suggests potential for applications in integrated I We acknowledge discussions with H. Park. This work was sup- sensor/detection systems, information storage, and other ported by the Air Force Office of Scientific Research and Defense areas of photonics. Advanced Research Projects Agency. We thank Andrew Greytak ur approach to nanoscale photonic devices is based for a gift of CdSe quantum dots upon sequential deposition of p-type and n-type NW mate 142 O 2005 Wiley-VCH GmbH &Co. KGaA, D-69451 Weinheim Dol:10,1002/sm2o400030Nanophotonic assemblies Nanowires for Integrated Multicolor Nanophotonics** Yu Huang, Xiangfeng Duan, and Charles M. Lieber* Nanoscale light-emitting diodes (nanoLEDs) with colors spanning from the ultraviolet to near-infrared region of the electromagnetic spectrum were prepared using a solution-based approach in which emissive electron-doped semiconductor nanowires were assembled with nonemis￾sive hole-doped silicon nanowires in a crossed nanowire architecture. Single- and multicolor nanoLED devices and arrays were made with colors specified in a predictable way by the bandgaps of the III–V and II–VI nanowire building blocks. The approach was extended to combine nanoscale electronic and photonic devices into integrated structures, where a nanoscale transistor was used to switch the nanoLED on and off. In addition, this approach was generalized to hybrid devices consist￾ing of nanowire emitters assembled on lithographically patterned planar silicon structures, which could provide a route for integrating photonic devices with conventional silicon microelectronics. Lastly, nanoLEDs were used to optically excite emissive molecules and nanoclusters, and hence could enable a range of integrated sensor/detection “chips” with multiplexed analysis capabilities. Keywords : · electroluminescence · LEDs · nanowires · optoelectronics · photonics Bottom-up assembly of nanoscale building blocks into in￾creasingly complex structures offers the potential to produce devices with novel function since it is possible to combine in a general way materials with distinct chemical composition, structure, size, and morphology, in contrast to planar device fabrication.[1–3] Semiconductor nanowires (NWs)[1] and carbon nanotubes[3] are especially attractive building blocks for assembling active and integrated nanosystems since the individual nanostructures can function as both device ele￾ments and interconnects. This concept has been demonstrat￾ed in nanoelectronics with the assembly of a variety of devi￾ces, such as field-effect transistors (FETs)[4–7] and integrated NW logic gates,[8, 9] and in nanophotonics with the assembly of, for example, individual light-emitting diodes[5, 10] and laser diodes.[11] The assembly of chemically distinct nanoscale building blocks that would otherwise be structurally and/or chemical￾ly incompatible in a sequential growth process typical of planar fabrication has received considerably less attention. However, this capability of the bottom-up approach should allow for assembly of nanostructures with function not read￾ily obtained by other methods and open new opportunities. For example, planar silicon, which serves as the foundation for the microelectronics industry, is poorly suited to many photonic applications since it has a poor efficiency for light emission.[12] Here we demonstrate the assembly of a wide range of efficient direct-gap III–V and II–VI NWs with sili￾con NWs (SiNWs) and planar silicon structures to produce multicolor, electrically driven nanophotonic and integrated nanoelectronic–photonic systems. The flexibility of our ap￾proach suggests potential for applications in integrated sensor/detection systems, information storage, and other areas of photonics. Our approach to nanoscale photonic devices is based upon sequential deposition of p-type and n-type NW mate￾rials into a crossed NW architecture using directed fluidic assembly[13] (Figure 1 a), where the cross points are electri- [*] Dr. Y. Huang, Dr. X. Duan, Prof. C. M. Lieber Department of Chemistry and ChemicalBiology, Division of Engi￾neering and Applied Sciences Harvard University Cambridge, Massachusetts 02138 (USA) E-mail: cml@cmliris.harvard.edu [**] We acknowledge discussions with H. Park. This work was sup￾ported by the Air Force Office of Scientific Research and Defense Advanced Research Projects Agency. We thank Andrew Greytak for a gift of CdSe quantum dots. Supporting information for this article is available on the WWW under http://www.small-journal.com or from the author. 142 < 2005 Wiley-VCH Verlag GmbH & Co. KGaA, D-69451 Weinheim DOI: 10.1002/smll.200400030 small 2005, 1, No. 1 full papers C. M. Lieber et al