Driven by the strong industry focus to enhance capabilities and efficiency of LEDs, the LED market is constantly growing. The technology is tapping new market opportunities and expanding its presence from computer and consumer electronics to control lights in cars and lighting applications. However, while in some applications the broad angular light emission is a strong advantage; it is at the same time a limiting factor in other possible uses.
Interesting conclusions on the possibility of enhancing the performance of LED devices are provided as a result of the research conducted at the Institute of Photonic Sciences (ICFO), Spain. The project, aimed at examining the propagation of light through layers of semiconductor nanowires and nanorods, has demonstrated that it is possible to control the emission of light from arrays of nanowires by growing such structures in a specific pattern. In addition, it is possible to optimize the emission of light by placing the emitting segment at a specific position along the nanowires.
Arrays of heterostructured InP-InAsP-InP nanowires have been fabricated using the vapor-liquid-solid (VLS) growth mechanism by metal-organic vapor phase epitaxy (MOVPE). In the next step, the period arrangement of the nanowires, which form a 2D photonic crystal slab, is achieved by the means of nanoimprint lithography. These nanowires come in a diameter of 90 nanometers, and a lattice constant of 510 nanometers. Silke Diedenhofen, postdoctoral researcher at ICFO, told Technical Insights,"The nanowires are grown in a bottom-up process that requires a metal catalyst particle. The metal particles are structured by nanoimprint lithography. Nanoimprint lithography allows patterning of structures on wafer-scale in a cost-efficient manner. By choosing an optimum structure of the metal particles, the nanowires can be grown such that the emission of light has the preferred direction. By growing the emitting segment at a specific height of the nanowires, the emission of light can be further maximized."
The proposed technology is interesting as it provides a base for future improvement in the efficiency and directionality of LED emission. Diedenhofen said, "Our work is fundamental research aiming to understand light emission from nanostructures. There is still need for long-term nanowire research, before a nanowire LED will enter the market. For fabricating LEDs based on nanowires, not only the optical, but also the optoelectronic function has to be optimized." The proposed concept has a strong potential to be applied in a design of nanowire-based LEDs and single-photon sources with significantly enhanced capabilities.
Interesting conclusions on the possibility of enhancing the performance of LED devices are provided as a result of the research conducted at the Institute of Photonic Sciences (ICFO), Spain. The project, aimed at examining the propagation of light through layers of semiconductor nanowires and nanorods, has demonstrated that it is possible to control the emission of light from arrays of nanowires by growing such structures in a specific pattern. In addition, it is possible to optimize the emission of light by placing the emitting segment at a specific position along the nanowires.
Arrays of heterostructured InP-InAsP-InP nanowires have been fabricated using the vapor-liquid-solid (VLS) growth mechanism by metal-organic vapor phase epitaxy (MOVPE). In the next step, the period arrangement of the nanowires, which form a 2D photonic crystal slab, is achieved by the means of nanoimprint lithography. These nanowires come in a diameter of 90 nanometers, and a lattice constant of 510 nanometers. Silke Diedenhofen, postdoctoral researcher at ICFO, told Technical Insights,"The nanowires are grown in a bottom-up process that requires a metal catalyst particle. The metal particles are structured by nanoimprint lithography. Nanoimprint lithography allows patterning of structures on wafer-scale in a cost-efficient manner. By choosing an optimum structure of the metal particles, the nanowires can be grown such that the emission of light has the preferred direction. By growing the emitting segment at a specific height of the nanowires, the emission of light can be further maximized."
The proposed technology is interesting as it provides a base for future improvement in the efficiency and directionality of LED emission. Diedenhofen said, "Our work is fundamental research aiming to understand light emission from nanostructures. There is still need for long-term nanowire research, before a nanowire LED will enter the market. For fabricating LEDs based on nanowires, not only the optical, but also the optoelectronic function has to be optimized." The proposed concept has a strong potential to be applied in a design of nanowire-based LEDs and single-photon sources with significantly enhanced capabilities.
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