Advanced quantum dot configurations

We present an overview on approaches currently employed to fabricate advanced quantum dot configurations by epitaxial growth. Widely investigated self-assembled quantum dots, i.e. In(Ga)As/GaAs and (Si)Ge/Si, are first introduced. Different quantum dot structures can be derived from In(Ga)As quantum dots by combining them with in situ etching, by layer stacking or by using them as stressors. Other fabrication methods include droplet epitaxy and multilayer deposition on hole patterned substrates.The combination of bottom–up and top–down methods results in absolute position control of self-assembled quantum dots. We review these 'seeded quantum dot crystals' in detail. Finally, we discuss a promising approach to realize quantum dot crystals with controlled spatial and optical properties.