Introduction of a hybrid MOSFET-IGBT power switching device utilising a novel Schottky biased minority carrier injector

A new minority carrier injector is described and demonstrated via simulation within an otherwise standard Vertical Diffused Metal Oxide Semiconductor Field Effect Transistor (VDMOSFET) structure forming an injected hybrid device. The resultant hybrid structure is directly compared to a standard Insulated Gate Bipolar Transistor (IGBT) and unipolar VDMOSFET of identical Blocking Voltage (BV). The hybrid is shown to be a latch up free device which switches an inductive load within a comparable time frame to a unipolar MOSFET, and yet at an ambient heat-sink temperature of 300 Kelvin the bipolar hybrid achieved double the current density of the unipolar MOSFET at Gate to Cathode voltage (V
_GK
)=20V, Anode to Cathode voltage (V
_AK
)=2V. At 400 Kelvin, V
_GK
=20V, V
_AK
=1.65V the specific on state resistance (RAK
_ONSP
) of the hybrid was found to be 1.14mOhm.cm2 as compared to 3.26mOhm.cm
²
of the unipolar MOSFET. The net effect of this hybrid device is to provide lowest on state loss MOSFET type performance from V
_AK
=0.1V with built-in, self biased, bipolar protection in the event of surge current. Any increase in junction temperature as a result of surge current or over voltage only serves to assist the onset of the low loss bipolar mode. The concept is to target the 600V market.