An insulated-gate bipolar transistor (IGBT) is a three-terminal power semiconductor device primarily forming an electronic switch.

It is used in switching power supplies in high-power applications: variable-frequency drives (VFDs) for motor control in electric cars, trains, variable-speed refrigerators, and air conditioners, as well as lamp ballasts, arc-welding machines, photovoltaic and hybrid inverters, uninterruptible power supply systems (UPS), and induction stoves.

[citation needed] An IGBT cell is constructed similarly to an n-channel vertical-construction power MOSFET, except the n+ drain is replaced with a p+ collector layer, thus forming a vertical PNP bipolar junction transistor.

This additional p+ region creates a cascade connection of a PNP bipolar junction transistor with the surface n-channel MOSFET.

[1][2][3][4][5] The bipolar point-contact transistor was invented in December 1947[9] at the Bell Telephone Laboratories by John Bardeen and Walter Brattain under the direction of William Shockley.

[13] The basic IGBT mode of operation, where a pnp transistor is driven by a MOSFET, was first proposed by K. Yamagami and Y. Akagiri of Mitsubishi Electric in the Japanese patent S47-21739, which was filed in 1968.

[14] In 1978 J. D. Plummer and B. Scharf patented a NPNP transistor device combining MOS and bipolar capabilities for power control and switching.

The IGBT is the most rugged and the strongest power device yet developed, affording ease of use and so displacing bipolar transistors and even gate turn-off thyristors (GTOs).

The electrical characteristics of GE's device, IGT D94FQ/FR4, were reported in detail by Marvin W. Smith in the proceedings of PCI April 1984.

[33] To test the lack of latch-up, the prototype 1200 V IGBTs were directly connected without any loads across a 600 V constant-voltage source and were switched on for 25 microseconds.

It was demonstrated that the product of the operating current density and the collector voltage exceeded the theoretical limit of bipolar transistors, 2×105 W/cm2 and reached 5×105 W/cm2.

High pulse ratings and low prices on the surplus market also make them attractive to the high-voltage hobbyists for controlling large amounts of power to drive devices such as solid-state Tesla coils and coilguns.

The IGBT combines the simple gate-drive characteristics of power MOSFETs with the high-current and low-saturation-voltage capability of bipolar transistors.

The IGBT combines an isolated-gate FET for the control input and a bipolar power transistor as a switch in a single device.

The IGBT is used in medium- to high-power applications like switched-mode power supplies, traction motor control and induction heating.

As the blocking voltage rating of both MOSFET and IGBT devices increases, the depth of the n- drift region must increase and the doping must decrease, resulting in roughly square relationship decrease in forward conduction versus blocking voltage capability of the device.

The wearout failures mainly include bias temperature instability (BTI), hot carrier injection (HCI), time-dependent dielectric breakdown (TDDB), electromigration (ECM), solder fatigue, material reconstruction, corrosion.

The overstress failures mainly include electrostatic discharge (ESD), latch-up, avalanche, secondary breakdown, wire-bond liftoff and burnout.