UC San Diego

The study of excitons in semiconductors is a rich field that has seen numerous beautiful developments during the seven decades since they were proposed by Frenkel [1931]. The exciton states in dielectric materials and molecular complexes are fundamental to understanding the full electronic structure of materials and the complex interactions between light and matter. Of particular interest is the fact that excitons, bound electron-hole pairs, form composite bosons with very low effective masses. This opens up an incredibly rich opportunity to study the phase space of quantum degenerate Bose gases at relatively high temperatures. An overview of many of the rich features that have been observed in exciton gases is presented. The system of indirect excitons in coupled quantum wells (CQWs) provides for drastically increased and tunable exciton lifetimes, leading to improved thermalization. The present experimental study presents a full steady state and dynamic model for the transport, generation, recombination, and thermalization of indirect excitons in CQWs, as well as methods for in-situ manipulation of indirect excitons by both optical and electrical methods. Both the optical and electrical methods for exciton control provide for dynamic manipulation of excitons on timescales significantly shorter than the lifetimes of indirect excitons