In the format of a single crystal, Magnesium Oxide serves as a substrate used in various semiconductor and photo-optic applications. To manufacture semiconductor devices, Magnesium oxide is provided as a substrate material– as single crystal boules or wafers. This single crystal substrate is used for epitaxial growth–the deposition of a crystalline over-layer on a crystalline substrate– of thin films of metal oxides or nitrides. These, in turn are used in the making of semiconductor devices such UV light emitters, visible light emitting diodes (LEDs) and laser diodes (LDs).
Single Crystal: A single crystal or mono-crystalline solid is a material in which the crystal lattice of the entire sample is continuous and unbroken to the edges of the sample, with no grain boundaries. The absence of the defects associated with grain boundaries can give mono-crystals unique properties, particularly mechanical, optical and electrical.