A silicon controlled rectifier (SCR) is a
Right Answer is:
Device with three junction
SOLUTION
Silicon-controlled rectifier or semiconductor-controlled rectifier is a four-layer solid-state current-controlling unidirectional device (i.e. can conduct current only in one direction).
The silicon control rectifier (SCR) consists of four layers of semiconductors, which form NPNP or PNPN structures, having three P-N junctions labeled J1, J2, and J3, and three terminals. Silicon is used as the intrinsic semiconductor, to which the proper dopants are added. The junctions are either diffused or alloyed (an alloy is a mixed semiconductor or a mixed metal). The anode terminal of an SCR is connected to the p-type material of a PNPN structure, and the cathode terminal is connected to the n-type layer. SCR is connected to the p-type material nearest to the cathode.