An SRC is made from adjoining layers of semiconductor material in which arrangement?

An SRC, or Silicon Controlled Rectifier, is indeed formed from a P-N-P-N arrangement of semiconductor materials. This structure is integral to its operation as a four-layer device.

In the P-N-P-N configuration, each layer plays a vital role in the device's ability to control electrical current. The alternating P (positive) and N (negative) layers create regions with different charge carriers: holes and electrons. This arrangement enables the SRC to function effectively as a switch, allowing it to control the flow of current through it by changing the state between conductive and non-conductive based on the applied gate signal.

This layered structure also contributes to the SCR's ability to withstand high voltages and currents, making it ideal for applications in power control. The four layers work together to create a device that can be turned on or off, meaning it can conduct current in one direction while blocking it in the opposite direction until a triggering signal is applied.

Other configurations, such as P-N-P or P-P-N arrangements, do not create the necessary characteristics that define the function of an SRC, explaining why they are not suitable for this particular question.