Q. Illustrate Power Semiconductor Devices?

Since the advent of the first thyristor or silicon-controlled rectifier (SCR) in 1957, tremendous advances have been made in power semiconductor devices during the past four decades. The devices can be divided broadly into four types:

• Power diodes

• Thyristors

• Power bipolar junction transistors (BJTs)

• Power MOSFETs (metal-oxide semiconductor field-effect transistors).

Thyristors can be subdivided into seven categories:

• Forced-commutated thyristor

• Line-commutated thyristor

• Gate turn-off thyristor (GTO)

• Reverse-conducting thyristor (RCT)

• Static-induction thyristor (SITH)

• Gate-assisted turn-off thyristor (GATT)

• Light-activated silicon-controlled rectifier (LASCR).

Whereas this comprehensive table, as of 1983, is given here for illustration purposes only, several new developments have taken place since then: A single thyristor is currently available with the capability of blocking 6.5 kV and controlling 1 kA. The 200-V Schottky barrier diodes are commercially available with ratings of several hundred amperes, up to 1 kA, and with blocking voltages as high as 1-5 kV.