Chapter 6 - Electronic and nuclear spin in the optical spectra of semiconductor quantum dots

Abstract

This chapter discusses the physics of spin in semiconductor quantum dots as measured through optical spectroscopy. The chapter discusses the recent introduction of single quantum dot spectroscopy and the ability to probe individual excitons made possible, to measure the fine-structure of single excitons. Photoluminescence spectroscopy of single quantum dots is treated with detail. Optical selection rules connect the electronic spin to the exciton polarization properties. Exchange and Zeeman interactions lead to fine structure of the localized exciton. These interactions are considered in detail for the cases of the exciton and the trion (the singly charged exciton). The chapter also discusses the hyperfine interaction between the electronic and nuclear spins. Under certain experimental conditions, the nuclear spin can become optically pumped into a high polarization state, which significantly affects the optical spectrum through the Overhauser effect. Fluctuations of nuclear spin polarization lead to the relaxation of the electronic spin, which is measurable in the optical spectrum through the Hanle effect.