GaN nanowires on a silicon platform eye novel optoelectronics
Nitride nanowires with a large surface-to-volume-ratio offer intriguing
optoelectronic properties that could advance integrated photonics.
BY HUABIN YU, YUANMIN LUO, WEI CHEN AND HAIDING SUN FROM THE UNIVERSITY OF SCIENCE AND TECHNOLOGY OF CHINA
One-dimensional semiconductor nanostructures, such as single-crystalline nanowires, are the key ingredient in emerging nanoscale optoelectronic devices. These miniature marvels promise to play a variety of roles, including serving in the ultimate form of integrated photonics.
It is possible to produce nanowires with a range of materials. They include the group III-nitrides, which offer direct and tuneable bandgaps. Nanowires made from this material system offer single-crystalline quality, realised through MBE growth that allows for full strain relief during the epitaxial process. Additional merits of nanowires, when produced by MBE, are precise morphology and size control - and thanks to a large surface area, an exceptional light absorption efficiency and light extraction efficiency.
Figure 1. The Photoluminescence spectra of (a) the pristine nanowires
and (b) nanowires coated with quantum dots. The scanning electron
microscopy image of GaN/AlGaN nanowires on a silicon substrate (c)
without a coating of quantum dots and (d) with a coating of quantum
dots. The scale bar is 1 µm. The electroluminescence spectra of the
nanowire device (e) without quantum dots, (f) and with quantum dots
under injection currents of 20 mA to 100 mA. Insets of (e) and (f) show
optical images when the devices are emitting light.
This wonderful set of attributes makes III-nitride nanowires a compelling candidate for a number of optoelectronic devices. These nanoscale structures could play a crucial role in LEDs, photodetectors, laser diodes, and even photoelectrochemical devices for chemical/biological photoelectronic sensors. Exploring all of these possibilities and more is our team from the iGaN Laboratory at the University of Science and Technology of China.