Researchers from the Institute of Semiconductor Technology at Braunschweig Technical University, the Paul Drude Institute in Berlin and OSRAM Opto Semiconductors in Regensburg have teamed up to study the growth of GaN nanorods with incorporated optically active InGaN quantum wells. Shaping of the nanostructures from pyramids to pencil-shaped nanocrystals to hexagonal rods has been achieved by the adjusting the hydrogen content within the H2/N2 carrier gas mixture during the metal-organic chemical vapour deposition (MOCVD) process.

The scientists have found a way to grow these structures in a standard large volume MOCVD system without using any catalyst or pulsed growth mode. Transmission electron micrographs (TEM) showed the morphological properties of the nanorods and the relation between lateral growth rate and semipolar side facets. Additionally, the growth of InGaN multiple quantum wells (MQW) on different side facets was successfully confirmed and cathodoluminescence measurements revealed different emission wavelengths from different parts of the nanorods.

Looking ahead

Growth on silicon substrates and the combination of nanoemitters with integrated electronic and photonic circuits is our vision for the future. What's more, the growth of highly efficient InGaN QWs on defect-free nanorod surfaces and the possibility to cover the tremendously increased surface with an active layer would enable more light output per substrate area for a bright future.

The researchers presented their work in the journal Nanotechnology.