Excitonic couplings and Stark effect in individual quantum dot molecules

Abstract

We present a comprehensive study of electric field effects upon the photoluminescence of individual quantum dot molecules. Using p-i-n diode structures, we are able to observe neutral, negatively and positively charged excitons, and biexcitons in a single device. Each molecule shows an extremely rich line structure which can be accurately described with a simple model. Moreover, reversing the doping sequence allows both electron and hole coupling between the dots to be investigated. High potential barriers cladding the quantum dot molecule allow the application of strong electric fields, resulting in a larger than expected quantum confined Stark effect.