MRI: Development of a Mid-infrared Optical Microscope for Investigation of Femtosecond Dynamics of Single Large Spin Orbit Semiconductor Heterostrucutures

University Of Cincinnati Main Campus, Cincinnati OH

Investigators

Abstract

The Division of Materials Research and the Major Research Instrumentation program supports the University of Cincinnati with the development of a unique instrument that will advance the understanding of a whole class of semiconductor materials that can provide the basis for new applications of these nanostructures. The combination of small size (in the nanoscale) and large spin-orbit interactions may enable these materials to operate at the very high speeds and low energies required for devices which might replace present day silicon-based circuits. Graduate students involved in the development of this instrument will learn technical skills and will develop substantial design skills. Involvement of an electronics company, which makes imaging products in this energy regime, provides the basis for interactions that could point to new directions for the company and result in future collaborative research efforts. Research efforts of this proposal will be included in the materials used for continuing public outreach efforts, including NanoDays at the Cincinnati Museum Cente. The development of a femtosecond pump-probe light scattering instrument will enable new studies of electronic- and spin-dynamics of single nanostructures which have extremely strong spin-orbit interactions and gaps in the Mid-Infrared. The mid-infrared 0.1 to 1 eV energy range poses significant challenges because of the lack of widely tunable laser sources or sensitive detectors. This mid-IR energy range covers an entire class of semiconductor materials which have excited both theoretical and experimental interest because of their extremely large spin-orbit coupling which enables the exploration and manipulation of spins using combined electric and magnetic fields. This development proposal takes advantage of two newly developed techniques for measuring energy structure and femtosecond dynamics in single nanostructures which will be extended into this mid-IR energy range: (A) Transient Rayleigh Scattering Spectroscopy (TRRS), where a pump pulse excites the nanostructure and the complex index of refraction is interrogated by the light scattered from a delayed probe pulse; and (B) Transient Photocurrent Spectroscopy (TPCS), where a pump pulse excites a photocurrent in a single nanostructure device and the non-equilibrium population of the electronic structure is interrogated with a delayed probe pulse.