SINGLE-CRYSTAL GROWTH

**Definition:** This place covers:

Single crystals or homogeneous polycrystalline material with a defined structure; production thereof.

Processes and apparatus used in obtaining these crystals and materials.

Processes and apparatus for the after-treatment of single crystals or homogeneous polycrystalline material with a defined structure.

**Limiting references (this place does not cover):** - Formation of diamonds using ultra-high pressure -> B01J3/06 - Casting of metals, casting of other substances by the same processes or devices -> B22D - Zone-refining of metals or alloys -> C22B - Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working -> C22F - Semiconductor devices; Electric solid-state devices not otherwise provided for -> H10

**Glossary:** - amorphous: description of a solid material not having long-range crystalline lattice structure. - bulk/layer: bulk crystals have dimensions which are comparable in all three dimensions whereas layers have one dimension (thickness) significantly less than the other two dimensions (surface area). Often a bulk layer is grown from a discrete "seed" whereas a layer is grown epitaxially on a substrate. - crystal: description of a solid material having long-range order of atoms or molecules arranged in a regularly-repeating lattice structure. - defined structure: the structure of a solid material with grains which are oriented in a preferential way or have larger dimensions than normally obtained. - epitaxy: the formation of a crystalline layer on a substrate in such a manner that the formed crystal bears a definite crystallographic relationship to the substrate. - eutectic: description of a mixture or solution containing two or more phases at a composition that has the lowest melting point and where the phases simultaneously crystallise from solution at this temperature. - grains: crystalline regions in a solid material, each grain generally being a single crystalline region. - homogeneous polycrystalline material: a solid material with crystal particles, all of which have the same chemical composition. - lattice: an ordered arrangement of atoms or molecules within a solid material. - nanocrystals: single crystals having at least one dimension less than 100 nm. The term includes nanowires, nanotubes, nanorods etc. - oriented crystal: a polycrystalline structure in which the grains are generally aligned in a preferential direction such as obtained in columnar growth. - seed: a material, usually itself a small single-crystal, upon which a single-crystal is grown, the seeded crystal growth proceeding by the alignment of atoms or molecules or clusters into a thermodynamically favoured arrangement determined by the nature of the seed. - single-crystal: description of a solid material having long-range order of atoms or molecules in a regularly-repeating lattice structure. Also includes twin crystals and a predominantly single crystal product. - superlattice: a single-crystal having an internal structure of more than two layers, each layer having a composition different from the next adjacent layer. - twin crystal: a crystalline material in which the adjoining crystalline lattices have a mirror-image symmetrical relationship, the interface between the adjoining crystals being termed the twin plane. - whiskers/needles: discrete solid crystalline particles of generally elongated shape. Dimensions are superior to 100 nm and are not considered as nanocrystals (nanowires, nanorods etc.) - zone melting: description of a process in which a crystallised body is formed by melting a zone of a starting material with subsequent cooling and crystallisation while either the zone or the starting product is displaced so that all or part of the starting material is converted into the crystallised body.