UC San Diego

Over several decades, research in semiconductor physics has revealed a rich plethora of physical phenomena filled with electric, magnetic, and optical processes for physicists and engineers to observe and manipulate. In addition to hosting a number of fundamental discoveries in physics, several of which merited Nobel Prizes, semiconductor physics has also revolutionized modern technology, most notably in the field of computing.

An especially interesting topic in this field is the physics of quasiparticles, which are excitations or disturbances in matter that resemble particles in free space. This dissertation focuses on excitons, which are quasiparticles that exist in semiconductor materials and are a bound state of an electron and a hole. Excitons can interact with light, either through their photo-generation or by radiative recombination of the electron and hole, and therefore can aid in the study of the interaction of light and matter.

This dissertation in particular looks at a specially engineered system of excitons: indirect excitons in coupled quantum wells. In this system, the electron and hole of the exciton are confined to two separate quantum well layers and are as a result separated in space, typically by ∼ 10 nm, depending on the coupled quantum well structure.

Indirect excitons possess several unique properties including a built-in electric dipole moment, long lifetimes, energy control by applied voltage, and the ability to form a quantum Bose gas, making them a useful system to study fundamental physics of cold bosons and to investigate ways to integrate these properties into modern day technology. The experiments detailed in this dissertation probe the basic physics of exciton transport in high magnetic fields and expand upon our current understanding of how nano-scale devices can be used to control electronic and optical processes in solids.