InAs Quantum Dot Formation Studied at the Atomic Scale by Cross-sectional Scanning Tunnelling Microscopy

Abstract

Self-assembled quantum dots (QDs) have attracted much attention in the last years. These nanostructures are very interesting from a scientifi c point of view because they form nearly ideal zero-dimensional systems in which quantum confi nement effects become very important. These unique properties also make them very interesting from a technological point of view. For example, InAs QDs are employed in QD lasers, single electron transistors, midinfrared detectors, single-photon sources, etc. InAs QDs are commonly created by the Stranski–Krastanov growth mode when InAs is deposited on a substrate with a bigger lattice constant, like GaAs or InP [10] . Above a certain critical thickness of InAs, three-dimensional islands are spontaneously formed on top of a wetting layer (WL) to reduce the strain energy. Once created, the QDs are subsequently capped, a step which is required for any device application. Self-assembled quantum dots (QDs) have attracted much attention in the last years. These nanostructures are very interesting from a scientifi c point of view because they form nearly ideal zero-dimensional systems in which quantum confi nement effects become very important. These unique properties also make them very interesting from a technological point of view. For example, InAs QDs are employed in QD lasers, single electron transistors, midinfrared detectors, single-photon sources, etc. InAs QDs are commonly created by the Stranski–Krastanov growth mode when InAs is deposited on a substrate with a bigger lattice constant, like GaAs or InP. Above a certain critical thickness of InAs, three-dimensional islands are spontaneously formed on top of a wetting layer (WL) to reduce the strain energy. Once created, the QDs are subsequently capped, a step which is required for any device application.