Semiconductor nanowires are one dimensional structures that have been used as building blocks for a variety of nanoscale electronic and photonic devices. In a recent article published in Nanotechnology the authors demonstrate infrared nanoscale LEDs on silicon substrates.

The nanowire LEDs are so called core-shell structures based on III-V semiconductors. Light generation takes place in a GaAs nanowire with an InGaP cladding layer providing the n-contact (see figure). The silicon substrate functions as a template for epitaxial growth and as an electrically integrated p-region for the devices. The use of silicon as a growth template can drastically reduce the cost of producing electronic and photonic devices due to inexpensive substrates and opportunities for large-scale processing. What enables successful integration of LEDs on silicon is the small footprint of the nanowire that accommodates the strain from lattice and thermal expansion coefficient mismatches of the two semiconductor materials.

A major achievement in the present work is the successful use of planar process technologies, which the scientists in Lund have developed for nanowire transistors, for the realization of nanowire LEDs. It was demonstrated, for example, that the position of each individual nanowire could be controlled by lithography. This enables more advanced devices such as LEDs integrated/combined with photonic crystals and nanostructured surfaces for improved light extraction.

The light-generating properties, including EL spectra and radiation pattern, of these nanoscale beacons are reported in the article. The light-generating efficiencies of these novel devices are still substantially below that achieved by planar commercial LEDs, but the integration with silicon and the nanoscale size of these devices may open up for completely new types of applications, say the inventors. III-V nanowires may be the ”bright” future of silicon.