As discussed in Chap. 8, there was a flurry of activity in the 1990s to explore the development of MOS-gated thyristor structures due to their reduced on-state voltage drop when compared with the IGBT structure. The base-resistance-controlled thyristor (BRT) structure was proposed 1, 2 to take advantage of thyristor-based on-state current flow under MOS gate control to reduce the gate drive requirements. In comparison with the MCT structure discussed in the previous chapter, the BRT structure had the advantage of using a double-diffusion process similar to that used to manufacture IGBT structures. A rigorous study to understand the physics of BRT operation and evaluate the performance of experimental devices with blocking voltages ranging from 600 to 5,000 V was conducted in the 1990s 3–9.