Simulation Study of a Novel Snapback-Free and Low Turn-Off Loss Reverse-Conducting IGBT With Controllable Trench Gate

Abstract

A novel ultra-fast snapback-free controllable trench gate (CTG) reverse-conducting insulated gate bipolar transistor (RC-IGBT) is proposed and investigated by simulation. It features a CTG in the collector side and a bias voltage ( ${V}_{\text {RC}}$ ) is applied between the CTG and collector electrode. In the forward conduction state with ${V}_{{\text {RC}}} , a high-density hole inversion layer is formed around the CTG. The CTG acts as not only a folded controllable hole injector to enhance the hole injection efficiency, but also an electron barrier to increase the distributed resistance. The CTG RC-IGBT achieves a low on-state voltage drop ( ${V}_{{ \mathrm{\scriptscriptstyle ON}}}$ ) and snapback-free with a small cell pitch. In the blocking state with ${V}_{\text {RC}} > {0}$ , an electron accumulation layer is formed around the CTG. The electron layer together with the CTG acts as an equivalent N-buffer layer to stop the electric field and support high breakdown voltage. During turn-off, the CTG RC-IGBT behaves like a unipolar device without long tail current because the hole injection is deactivated by properly switching the ${V}_{\text {RC}}$ . Compared with conventional RC-IGBT, the proposed device decreases the ${V}_{\text {on}}$ and turn-off energy loss ( ${E}_{\text{off}}$ ) by 34% and 74%, respectively, under the load current of 100 A/cm2 and bus voltage of 600 V.