TIL: kinds of solid state

There are two kinds of solid state - crystalline solids and amorphous solids.

Crystalline solids like diamond have recurring structural patterns (over long-range) while amorphous solid don’t have long-range or repeating lattice structure. This leads to interesting properties. Like crystalline solids have sharp melting points; but amorphous solids like rubber or glass would soften over a range of temperatures due to lack of repeating structure. Similarly, electrical conductivity in crystalline solids can be high (in conductors) or low (in insulators); while amorphous solids typically have low conductivity due to lack of long-range structure. Another example is crystalline solids have well-defined planes of weakness, whereas amorphous solids break in irregular patterns.

Semiconductors can be both kind. Silicon and Germanium typically have repeating lattice structure, and can be mixed with impurities to control their conductivity. Whereas amorphous semiconductors can still conduct electricity, and might be preferred in some scenarios due to manufacturing simplicity and cost (can be produced at lower temperature and simpler processes for example); amorphous semiconductors are also flexible and so can be used for flexible electronics like flexible displays; Also, There are techniques to spread the semiconductors evenly over a uniform surface.