Vapour Growth

Abstract

The growth of crystals having a relevant size proceeds in nearly all cases from a fluid phase. Compared with liquids (melts, high temperature fluxes, aqueous and other solutions) the species have the highest mobility in the gas, but their volume concentrations (c = n/v, n = number of moles, v = volume) are low. Under certain circumstances, crystals can be grown at remarkable lower temperatures from a gas phase than from a melt, thus allowing crystallization of compounds with restricted high temperature stability. Often methods of vapour growth are easy to handle, thus allowing the growth of small crystals with low expense. We will introduce to the methods, to some theoretical models which help to predict the processing behavior and to control stoichiometry and compositions in complex materials. We will not discuss in detail the peculiarities of the application of chemical vapour deposition (CVD) methods for thin film preparation and also neglect physical methods applying excited conditions (Laser, ion or electron beams etc.) for that purposes. A compilation of methods and materials can be found in refs. [1–4].