Nanophotonics - research challenges and applications

The talk will discuss several examples of nanophotonic light sources where structures with a low-dimensional electronic confinement (quantum dots/quantum dashes) are combined with structures for photon confinement (photonic crystals). Quantum dots are usually fabricated by self-organized growth techniques where a semiconductor material with a large lattice constant is deposited on a substrate with a smaller one. After the formation of a very thin wetting layer, it is energetically favourable to form three-dimensional structures with typical dimensions on the order of a few to several ten nanometers. There are several advantages of quantum dots over quantum wells, e.g. the possibility to extend the wavelength range accessible with a given material system, a reduced carrier diffusion and a reduced linewidth enhancement factor. In some material systems, the shapes of the structures fabricated by self- organized growth are not round, but rather elongated. These structures are called quantum-dashes.