By: Kyle Logan MEEN 3344

 Crystals have special desired optical and electrical properties  Growing single crystals to produce gem quality stones  Industrial applications  Money

 The driving force for crystallization comes from the lowering of the potential energy of the atoms or molecules when they form bonds to each other.

 CVD  A slice of material is placed in a chamber  A vapor form or hydrocarbon gas is introduced into a high pressure, high temperature atmosphere (58,000 2,300°F for diamonds)  Atoms land on the surface of the slice  The crystal can be cut to applications  Bridgman  Material is melted, starting at one end to the other. At a pace from 5-50 mm/day

 Compared to other growth methods, Bridgman method is considered to be a rather simple crystal growth method, but several limitations still exist.  The Bridgman method can not be applied to a material system which decomposes before it melts, systems having components with high vapor pressure, and materials exhibiting destructive solid - solid phase transformations which will compromise the crystalline quality on cooling the crystal at the end of the growth run.

 Strains develop during growth and can be reduced by thermal annealing.  Thermal annealing is where the crystals are heated at a particular rate to a particular temperature, then kept there for a particular time duration and then slowly cooled down to room temperature.

 For optical or electrical use the single crystals are cut into thin wafers around microns, then polished and then etched to remove imperfections  For diamonds and gems, they are cut and shaped to the desired ranges or appearance, and then they are polished to remove imperfections

 Prior to any device fabrication process, the polished surface is sometimes etched in order to remove the damaged/ defective layer produced during polishing process.  Etchants are also useful for revealing bulk defects present in the crystals.  Some etchants are also used for determining the orientation of the crystal surface.

 Electrical- Silicon, Gallium Arsenide, Diamond, etc. for computer chips and other uses for semi conductors  Optical- Diamond, lasers, lenses, optical fiber. etc.  Industrial- Diamond cutting tools

 3-D Holographic optical storage  More powerful lasers  Diamond computer chips, instead of silicon  “Diamond is the hardest material, it won’t expand in heat, won’t wear, is chemically inert and optically transparent”. ~Paul May

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