UC San Diego

Semiconductors have proven themselves to be an excellent platform for both the development of new technologies and the study of fundamental physics. Various semiconductor materials provide us the ability to control and study the bulk system behavior, electronic behavior, and light matter interactions. Of particular interest to this paper is the study of a quasi-particle that can form in semiconductors known as an exciton. Made from an electron and hole, it also has very useful photonic properties. In our work we study excitons created by photoexcitation, where a laser excites an electron from the lattice, creating an electron and hole, the electrons and holes created can then form a bound state known as an exciton. Excitons can transform into photons via radiative recombination. Our experiments typically deal with a system of quantum wells, engineered to keep the electrons and holes spatially separated, a bound pair of an electron and hole with the electron and hole in different quantum wells is known as an indirect exciton. Some of the properties of indirect excitons are an electric dipole moment, energy controlled by voltage, long lifetimes, macroscopic transport, and they are bosons. These properties as well as their interaction with light allow for systems to be created that act as proof-of-concept prototypes for excitonic devices, as well as a platform to study fundamental physics of cold bosons. The work in this dissertation is primarily focused on dipole-dipole attraction and the formation of a Fermi edge singularity in these systems. These works give us new insights into the interactions of bosons and formation of new states of matter.