Compound semiconductors are formed by multy-elements, such as III-V compound, II-VI compound and IV-IV compound.

Compared with silicon semiconductors, compound semiconductor is far more expensive and much more difficult to produce large diameter crystal therefore silicon has been major semiconductor materials until nowadays.

However,compound semiconductor wafers are being used for applications like LED,LD,solar battery and field-effect transistor and Hall elements based on its light-receiving and emitting,high speed motion and magnetoelectric function.

For example,Sapphire,Silicon Carbide (SiC),Gallium Arsenic(GaAs),Gallium Phosphorus(GaP) and Gallium Nitride substrate are being used according to LED application characteristics and thin deposition (epitaxial layer) is formed on substrate in order to produce device function.