monocrystal

Monocrystal, or single crystal, is a solid material in which the crystal lattice is continuous and unbroken throughout the specimen, with no grain boundaries. This contrasts with polycrystalline materials, which are made of many crystalline grains, and with amorphous substances that lack long-range order.

Single crystals exhibit anisotropic properties; mechanical, optical, and electronic characteristics vary with crystallographic direction. This directional dependence is critical in applications such as electronics, optics, and photonics. Common single-crystal materials include silicon, quartz, sapphire, gallium nitride, and diamond.

Growth methods include the Czochralski process, float-zone refining, and Bridgman-Stockbarger techniques to produce large, high-quality boules; hydrothermal growth is used for synthetic quartz; chemical vapor deposition builds single-crystal films for diamond and other hard materials.

Applications span electronics, photovoltaics, optics, and jewelry. Silicon wafers, optical components from quartz or sapphire, and synthetic gemstones rely on single crystals. Single crystals are also used in resonators, LED substrates, and high-performance detectors, where uniform lattice properties are essential for performance.

Because single crystals lack grain boundaries, their defects, impurities, and dislocations set limits on performance. Characterization uses X-ray diffraction and other crystallography techniques; crystal orientation and surface quality are critical for device fabrication.