Nature Mater. 10, 676–681 (2011)

Three-dimensional photonic crystals (3D PCs) are a promising platform for developing zero-threshold lasers, low-loss waveguides, high-efficiency LEDs and solar cells. However, the optoelectronic properties of 3D PCs are often unsuitable for practical applications because unoccupied chemical bonds at the device surface function as carrier traps, resulting in non-radiative recombination and consequently a significant decrease in device efficiency. Erik Nelson and co-workers from Kyoto University in Japan and the University of Illinois at Urbana-Champaign and the University of California at Santa Barbara in the USA have now used 3D-template-directed epitaxial growth to fabricate a 3D PC LED. They fabricated a 3D structure with a lattice constant of 735 nm by filling a polymer template with alumina, removing the polymer and then epitaxially growing GaAs by metal–organic chemical vapour deposition. After fabricating the 3D framework, the researchers grew single-quantum-well GaAs/AlGaAs/GaAs as a passivation layer on the device surface. The 3D PC LED had a 15-nm-thick active layer of InGaAs and a cylindrical shape with a diameter of 120 μm. Electroluminescence spectra collected from the device showed a peak emission wavelength of 1,230 nm for drive currents of 2–8 mA.