Insulated gate transistor physics: Modeling and optimization of the on-state characteristics

The Insulated Gate Transistor (IGT) is modeled as a bi-polar junction transistor (BJT) driven by a MOSFET. The bipolar nature of the device is examined by studying the effects of carrier lifetime on electrical performance. This model also predicts the effects of the gate-oxide thickness, channel length, and cell spacing on the IGT forward characteristics for a 100-1200 V range in blocking voltage. The relative significance of the MOS/BJT components of the device has been explored. This is particularly important when optimizing designs over a wide range of voltage ratings. Careful attention to this has led to greater than a three times improvement in high-temperature dynamic latching current. This is the key to obtaining a wide safe operating area for the IGT. For the first time, an accurate and straightforward model of IGT has been developed. The model predictions are within 15 percent of the experimental data.