This is a normal single PN junction diode which is especially designed for switching purposes. This diode can exhibit two states of high and low resistance clearly which can be used alternatively.
The junction capacitance of this diode is made very low so as to minimize other effects. The switching speed is made quite high. When the diode has high resistance it works as an open switch and it acts as a closed switch during low resistance. This transition occurs at a faster rate in switching diode, than in any ordinary one.
These have many applications such as −