Diamond cubic

Diamond cubic

The diamond cubic crystal structure is a repeating pattern that atoms may adopt as certain materials solidify. While the first known example was diamond, other elements in group IV also adopt this structure, including tin, the semiconductors silicon and germanium, and silicon/germanium alloys in any proportion.
















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Since this class of material is important for electronics, it is important to know that they present open, hexagonal ion channels when ion implantation is carried out from any of the <110> directions (that is, 45 degrees from one of the cube edges). Their open structure also results in a volume reduction upon melting or amorphization, as is also seen in ice.

They display octahedral cleavage, which means that they have four planes—directions following the faces of the octahedron where there are fewer bonds and therefore points of structural weakness—along which single crystals can easily split, leaving smooth surfaces. Similarly, this lack of bonds can guide chemical etching of the right chemistry (i.e., potassium hydroxide solutions for Si) to produce pyramidal structures such as mesas, points, or etch pits, a useful technique for MEMS.