摘要： This chapter focuses only on quantum dots (QDs) embedded inside a semiconductor structure, like quantum wells (QWs) or partly quantum wires (QWrs). Freestanding QDs with a much larger application field, which can be prepared from the same material, are not covered in this chapter. The reason for this is that we will write about MOVPE QD preparation only (not, for example, about colloidal, metal, or other freestanding QDs). A research report about the market for the whole family of QDs can be found in [1]. QDs are small pieces of semiconductor nanocrystals (mainly) with sizes in the range from a few to tens of nanometers. The first idea of QDs having properties different from those of the bulk material was published by Ekimov and Onushchenko in 1981 [2]. Their QDs were prepared in colloidal solution, not yet QDs embedded in the heterostructure: “The exciton absorption spectrum of microscopic CuCl crystals grown in a transparent dielectric matrix has been studied. The size of the microscopic crystals was varied in a controlled manner from several tens of angstroms to hundreds of angstroms. There is a short‐wave shift (of up to 0.1 eV) of the exciton absorption lines, caused by a quantum size effect” [2]. During the early 1990s, embedded QDs were prepared by molecular beam epitaxy (MBE) [3–7] in several laboratories, as described in [8]. MOVPE‐grown QDs were reported in 1991 [9, 10], but with little response (12 and 0 citations, respectively). MBE seems to be more suitable for attaining an exact layer thickness down to fractions of a monolayer. QD MOVPE papers published later [11–14] attracted much more interest. An attempt to realize industrial MOVPE‐prepared QD‐based semiconductor lasers for fiber optic telecommunications appeared during the first years of this century (EU project DOTCOM 2002–05), but without a real impact on industrial production.