(Invited) Shape Engineering of Nanostructured III-V Semiconductor Lasers

Abstract

Group III-V semiconductors have revolutionised electronics and optoelectronics due to their superior physical and optoelectronic properties including high carrier mobility, direct bandgap and band structure engineering capability. Reducing the device size to nanoscale brings many unique properties, such as large surface-area-to-volume ratio, high aspect ratio, carriers and photons confinement effect. These nanostructures have already been demonstrated for potential applications in light emitters, photodetectors, solar cells and for photoelectrochemical water splitting. However, to date most efforts on the growth of these nanostructures have been limited to nanowires.In this talk, we demonstrate selective area growth of III-V nanostructures, showing the possibility of obtaining other functional nanostructures, beyond the limitation of rod-like geometry. We demonstrate that by changing the pattern design on the mask and growth conditions, we are able to grow and control the shapes to form nanostructures such as membranes, flowers, rings, spirals, stars, ellipses etc. These shape-engineered nanostructures open up possibilities of new applications based on devices with novel geometries.In particular, we will show the results of our InP micro-ring lasers which have excellent cavity due to the atomically flat facets. Micro-disk and micro-ring lasers are light emitting devices that operate in the whispering gallery mode. They are important components for integrated photonics applications as light from can these devices can be efficiently coupled to on-chip waveguides. By coupling the micro-ring laser to a nanowire antenna, we further demonstrate that we can tune the emission directionality to the device.