Spectroscopy of Semiconductor Nanostructures in High Magnetic Fields

William Marsh Rice University, Houston TX

Investigators

Abstract

TECHNICAL ABSTRACT: Solids in strong magnetic fields have exhibited an array of exotic phenomena for the past several decades. A magnetic field produces drastic modifications in electronic energy spectra through orbital (Landau) quantization and spin (Zeeman) splitting. In particular, quantum-confined semiconductor structures in magnetic fields are ideal for studying non-trivial effects in a systematic manner with fully tunable electron densities, densities of states, and confinement energies. The proposed research will address fundamental questions related to quantum coherence and interactions in nanostructures such as: How will independent electron-hole pairs develop macroscopic coherence? How stable will one-dimensional excitons be at quantum degenerate densities? and How will resonant electron-phonon interactions modify energy levels of Dirac fermions? Clarifying these questions will not only advance our understanding of carrier interactions in solids, but also open up new device possibilities for utilizing coherent and many-body effects. In addition, training undergraduate and graduate students in cutting-edge projects will produce next generation experts in semiconductor optics. Finally, through the unique linkage with the PI's NSF Partnerships for International Research and Education grant, a unique opportunity will be provided for alumni of the NanoJapan: Summer Nanotechnology Research Program for Undergraduates to further their research experience with a summer internship at the National High Magnetic Field Laboratory. NON-TECHNICAL ABSTRACT: Solids placed in super-strong magnetic fields can sometimes exhibit bizarre phenomena, including the quantum Hall effect where the resistance vanishes at special values of magnetic fields. A magnetic field drastically modifies electrons' energies in solids through orbital quantization and spin splitting, thereby providing a powerful means for controlling quantum phenomena. In particular, nanostructures in magnetic fields are ideal for studying complicated effects in a highly-controllable manner. Advances in crystal growth and nanofabrication technology allow one to obtain samples of highest crystallinity with tailored properties. This project will examine novel magnetic-field-induced phenomena in three prototypical nanosystems -- semiconductor quantum wells, carbon nanotubes, and graphene -- through magneto-optical experiments. These studies will not only advance our understanding of electron behaviors in solids but also open up new possibilities for optoelectronic devices. In addition, undergraduate and graduate students will be trained in cutting-edge projects to become next generation experts in semiconductor optics. Furthermore, through the unique linkage with the PI's NSF Partnerships for International Research and Education grant, alumni of the NanoJapan: Summer Nanotechnology Research Program for Undergraduates will be invited to further their research experience with a summer internship at the National High Magnetic Field Laboratory (NHMFL). They will be given strong encouragement to pursue further graduate study and research in this field through the direct mentorship of graduate students and NHMFL researchers.