A1: Synthesis from Melt

Synthesis from the melt is the method of choice to create single-crystalline or polycrystalline material and alloys. It is used at the industrial scale (e.g., for semiconductors, solid-state lasers, optical components, steel). The sample quality depends sensitively on the temperature distribution in and the design of the growth apparatus. Establishing accessible data that characterize the resulting temperature distribution is crucial but comes with substantial effort. Since most of the data are not accessible in situ, this requires experimentally verified simulations by computational fluid dynamics. Entering log data for parameters like pressure, temperature, and growth rate of the sample must be linked in the form of a uniform metadata schema.

The design of the growth equipment is highly customized and very often protected, which makes metadata generation a challenge. There are several basic crystal-growth techniques from the melt, which are crystal pulling (Czochralski, Kyropoulos, Stepanov methods, etc.), the Bridgman method (vertical Bridgman, horizontal Bridgman, directional solidification, vertical gradient freeze method, etc.), skull-melting methods, zone melting, and the Verneuil process. Each of these techniques has its advantages or disadvantages regarding growth rates, equipment and consumable costs, degree of automation, level of impurities, feedstock requirements, crystal size control, etc. The choice of the most suitable growth technique depends on the targeted crystal quality for specific applications as well as on economic considerations.