Integration of site-controlled pyramidal quantum dots and photonic crystal membrane cavities

The authors demonstrate the deterministic coupling between a single, site-controlled $InGaAs∕GaAs$ pyramidal quantum dot (QD) and a photonic crystal membrane cavity defect. The growth of self-ordered pyramidal QDs in small (⁠$300nm$ base side) tetrahedral recesses etched on $(111)B$ GaAs substrates was developed in order to allow their integration within the thin GaAs membranes. Accurate (better than $50nm$⁠) positioning of the QD with respect to the optical cavity mode is achieved reproducibly owing to the site control. Coupling of the dot emission with the cavity mode is evidenced in photoluminescence measurements. The deterministic positioning of the pyramidal QDs and the control of their emission spectrum opens the way for devices based on QDs integrated with coupled nanocavities.