Engineering the surface and waveguide properties of nanowires

Abstract

Optoelectronic devices like LEDs, lasers and solar cells have become ubiquitous in our lives. They are a class of devices that rely on light-matter interactions and electronic properties of matter to convert light into electric signal or vice-versa. There has always been a drive to improve light-matter interactions in semiconductor materials to make better optoelectronic devices. Semiconductor nanowires offer a unique platform to tailor light-matter interactions at the nanoscale. Nanowires are anisotropic structures with cross-section dimensions in the range of 10-100 nms and few microns in length. The shape anisotropy of nanowires result in large free surface areas that may degrade their optoelectronic properties. On the other hand, the shape anisotropy of nanowires also means that they behave as waveguides, very similar to optical fibres. The high index of III-V semiconductor nanowires however results in much stronger field confinement despite their small lateral dimensions. The guided modes supported in nanowires affect the light-matter interactions and can be tailored by simply changing the nanowire dimensions. I will discuss approaches to mitigate the surface effects and show how the guided modes supported in nanowires can be exploited to fabricate efficient optoelectronic devices.