(Invited) Manipulating Carrier Polarization in Semiconductor Nanocrystals

Abstract

Degenerately-doped semiconductor nanocrystals exhibiting tunable localized surface plasmon resonance (LSPR) have attracted significant attention in recent years due to their unique optoelectronic properties. Unlike noble metal nanoparticles, colloidal plasmonic semiconductor nanocrystals have LSPR frequencies tunable in the infrared region, which makes them appealing for terahertz imaging, heat-responsive devices, and surface-enhanced infrared spectroscopic measurements. Besides expanding the LSPR frequency range, plasmonic semiconductor nanocrystals could potentially bring about numerous other opportunities related to single-phase plasmon-exciton interactions. However, non-resonant nature of the LSPR and exciton in semiconductors has been a major obstacle toward realizing such opportunities. In this talk I will discuss the results of our recent work on the structure and composition dependent plasmonic properties of colloidal semiconductor nanostructures. I will particularly focus on generating robust excitonic splitting in degenerately-doped transparent metal oxide nanocrystals, enabled by non-resonant plasmon-exciton coupling in an external magnetic field. This phenomenon allows for controlling carrier polarization in semiconductor nanocrystals using circularly polarized light. Furthermore, the ability to control carrier localization and nanocrystal morphology allows for further manipulation of the excitonic splitting pattern and quantum states in these non-magnetic semiconductor nanostructures. Possible applications of this emerging class of multifunctional materials for new electronic and quantum information technologies will also be discussed.