Optical properties from a single GaAs quantum ring structure

We observed exciton and biexciton states in a single GaAs quantum ring at 4 K using micro photoluminescence system and investigated power/polarization dependent photoluminescence measurements to identify both exciton and biexciton states and fine structures states. The biexciton and exciton states showed quadratic (a ~ 2.1) and linear (a ~ 0.97) increasing power factors, respectively. As the excitation power is increased, the photoluminescence of exciton states shifts to higher energy slightly to fill the excited states gradually to confirm the existence of fine structure states. In addition, the large energy difference (~ 0.7 meV) from exciton states and (~ 0.9 meV) from biexciton states for the perpendicular polarization was observed as a function of polarization angles.