Size-Dependent Fine-Structure Splitting in Self-OrganizedInAs/GaAsQuantum Dots

A systematic variation of the exciton fine-structure splitting with quantum dot size in single $\mathrm{InAs}/\mathrm{GaAs}$ quantum dots grown by metal-organic chemical vapor deposition is observed. The splitting increases from $-80$ to as much as $520\mu \mathrm{eV}$ with quantum dot size. A change of sign is reported for small quantum dots. Model calculations within the framework of eight-band $\mathbf{k}·\mathbf{p}$ theory and the configuration interaction method were performed. Different sources for the fine-structure splitting are discussed, and piezoelectricity is pinpointed as the only effect reproducing the observed trend.