Prismatic quantum heterostructures synthesized on molecular-beam epitaxy GaAs nanowires.

Semiconductor nanowires have stimulated extensive interest in the last decade because of their potential use as building blocks in future generations of electronic and optoelectronic applications. Equally important, their singular geometry provides an opportunity to test fundamental quantum mechanical concepts and related phenomena. Even though significant advances have been made in the synthesis of nanowires and the fabrication of related devices, reproducible fabrication has mainly relied on the use of gold nanoparticles as a seed through the vapor–liquid–solid (VLS) or vapor–solid–solid (VSS) mechanism. However, gold is known as a deep-level trap in semiconductors that significantly reduces their optical and electronic transport performance. More complex structures that enable versatile electronic and photonic functions can be achieved when different materials are combined. Among the possible combinations, coaxial nanostructures synthesized by using the as-made nanowires as a core physical template are particularly interesting. Up to now, coaxial heterostructures have been considered for two main uses: i) the improvement of the performance of nanowire devices, where the shell is responsible for removing the surface states and to confine the carriers at the core, leading to the reduction of surface scattering; ii) engineering the optoelectronical properties of the core of a particular device, such as the fabrication of multicolor light-emitting diodes.