This scientific service project provides for other projects within the CRC the following tailored GaAs-based samples: Heterostructures with embedded (In,Ga)As quantum dots with tailored emission and biexciton binding energies. Schottky-diodes, which contain quantum dot molecules. GaAs/AlAs-based planar cavities with quantum wells in the active region for polarition experiments. Heterostructures with site-controlled quantum dots prepared by growth on pre-patterned substrates. All heterostructures are fabricated by molecular beam epitaxy.