Schottky diode has a metal semiconductor rectifying contac. If alluminium which is an acceptor impurity in silicon is attached to n-type silicon as a lead. The n-region near the surface where aluminium is deposited must be made highly n-type to achieve an ohmic contact. If aluminium is directly deposited on n-type silicon , arectifying contact is obtained. This shown in figure:

Here in figure.a the contact A is a rectifying contact and B is ohmic producing schottky diode.

The characteristics curve of schottky diode is shown in Fig C.