The principle of four-layer p–n–p–n switching was developed by Moll, Tanenbaum, Goldey, and Holonyak of Bell Laboratories in 1956.

[1] The practical demonstration of silicon controlled switching and detailed theoretical behavior of a device in agreement with the experimental results was presented by Dr Ian M. Mackintosh of Bell Laboratories in January 1958.

[2][3] The SCR was developed by a team of power engineers led by Gordon Hall [4] [5] [6] [7] and commercialized by Frank W. "Bill" Gutzwiller in 1957.

[9][10] According to Bill Gutzwiller, the terms "SCR" and "controlled rectifier" were earlier, and "thyristor" was applied later, as usage of the device spread internationally.

There are three modes of operation for an SCR depending upon the biasing given to it: In this mode of operation, the anode (+, p-doped side) is given a positive voltage while the cathode (−, n-doped side) is given a negative voltage, keeping the gate at zero (0) potential i.e. disconnected.

In this case junction J1 and J3 are forward-biased, while J2 is reverse-biased, allowing only a small leakage current from the anode to the cathode.

SCRs are available with reverse blocking capability, which adds to the forward voltage drop because of the need to have a long, low-doped P1 region.

Forward-voltage triggering occurs when the anode–cathode forward voltage is increased with the gate circuit opened.

When the SCR is near VPO a very small increase in temperature causes junction J2 to be removed which triggers the device.

SCRs and similar devices are used for rectification of high-power AC in high-voltage direct current power transmission.

Unlike an SCR, an SCS switches off when a positive voltage/input current is applied to another anode gate lead.

Unlike an SCR, an SCS can be triggered into conduction when a negative voltage/output current is applied to that same lead.