1. Amorphous - random 2. Poly-crystalline - local uniform arrangements 3. Crystalline (or single crystal) - uniform structure - predominantly used in semiconductors Amorphous and poly-crystalline semiconductors have applications in thin-film transistors used in LCDs [[Crystals]] = [[Bravais Lattice]] + [[basis]] ![[crystal_basis.png]] Two-atom basis allows: - Diamond structure - two of the same atom - Zinc blende structure - same structure as diamond - two different atoms - Wurtzite structure - hexagonal Bravais lattice