Monolithic Fabrication of Two-Color InAs Quantum Dots for Integrated Optical Devices by Using a Rotational Metal Mask

Abstract

Selective-area growth (SAG) of multiple sets of closely spaced two-color InAs quantum dots (QDs) on a 2-in. GaAs wafer was achieved using a rotational metal mask (MM) and the molecular beam epitaxy method. The MM with windows on a rotationally asymmetric pattern enabled 32 sets of closely spaced SAG regions on a 2-in. GaAs wafer by rotating the MM by 180°. By depositing In0.2Ga0.8As strain-reducing layers with different thicknesses on each selective-area-grown QD, the emission wavelengths of the QDs were controlled. In addition to the fabrication of multiple sets of QDs, we investigated the temperature distribution on the substrate surface during the SAG; the temperature distribution was observed to be affected by the heat radiation from the MM. We also improved the MM for obtaining QDs with uniform optical quality. The proposed method is a promising method for the mass production of QDs for use in various QD-based integrated device applications such as our proposed all-optical devices based on QDs and photonic crystal.