Selective growth of InAs/GaAs self-organized quantum dots by shadow mask technique

The 10-μm stripes of 3-stacked self-organized InAs QDs layers embedded in GaAs matrix were selectively grown on GaAs substrates by MBE with shadow mask technique. The shadow mask structure composed of a 1-μm GaAs mask layer and a 1.5-μm Al_0.5Ga_0.5As spacer layer was prepared by LPE and MBE. The window stripes were lithographically defined and were opened by conventional chemical etching. The self-organized QDs formation was observed by monitoring the 2D to 3D transition on an unpatterned GaAs substrate. PL spectrum from shadow mask sample confirms the QDs formation and reveals the different optical properties from QDs on the unpatterned substrate. The blue-shift of PL spectrum of QDs grown through shadow mask is due to the different dot sizes.