Question

explain how the process of doping is attained to achieve extrinsic semiconductors with different electrical properties ?

Answer 1

Intentional introduction of impurities into an intrinsic semiconductor is called doping.
The doped material is referred to as an extrinsic semiconductor.
The synthesis of n-type semiconductors may involve the use of vapor-phase epitaxy. In vapor-phase epitaxy, a gas containing the negative dopant is passed over the substrate wafer. In the case of n-type GaAs doping, hydrogen sulfide is passed over the gallium arsenide, and sulfur is incorporated into the structure.This process is characterized by a constant concentration of sulfur on the surface.

Types of doping
Diffusion
Molecular diffusion, often called simply diffusion, is a net transport of molecules from a region of higher concentration to one of lower concentration by random molecular motion. The result of diffusion is a gradual mixing of materials.

Ion implantation
In the ion implantation charged dopants (ions) are accelerated in an electric field and irradiated onto the wafer. The penetration depth can be set very precisely by reducing or increasing the voltage needed to accelerate the ions.
This process takes place at room temperature.