impurity density การใช้

Silicon has a nearly perfect lattice, impurity density is very low and allows very small structures to be built ( currently down to 16 nm ).
GaAs in contrast has a very high impurity density, which makes it difficult to build integrated circuits with small structures, so the 500 nm process is a common process for GaAs.
As in most thin films, different growth methods can result in significantly different defect and impurity densities and crystalline quality, resulting in a large variation of the electronic and optical properties.