Simulation Study of a Novel Low-Loss N-Channel SOI LIGBT With a Self-Adapted Parasitic Thyristor

A novel low loss silicon on insulator (SOI) lateral insulated gate bipolar transistor (LIGBT) is proposed and investigated by simulation. It features a self-adapted parasitic thyristor ( ${T} ^{\ast}$ ), which is introduced owing to a P-drift region and an N carrier-stored (CS)-layer at the cathode side (PT LIGBT). In the ON-state, the ${T} ^{\ast} $ is easily triggered as the sum of current gains of parasitic transistor (P $\boldsymbol {+}$ anode/N-buffer/P-drift and N-buffer/P-drift/N-CS) equals to one, and then the PT LIGBT could enter the bipolar conduction state without the snapback effect. During the voltage rising period of turning off, the triggered ${T} ^{\ast} $ remains ON-state for some time and prevents from forming and expanding depletion region in the P-drift, because the anode voltage ( ${V}_{\text {A}}$ ) is sustained by the low hole density quasi-neutral P-drift region and remains a low value. During this period, the ON-state ${T} ^{\ast} $ prolongs the voltage rising time and extracts excess carriers at low ${V}_{\text {A}}$ value, which greatly reduces the current dropping time. Therefore, the turn-off loss ( ${E}_{ \mathrm{\scriptscriptstyle OFF}}$ ) is obviously reduced. During short-circuit, the PT LIGBT introduces P-drift to create an additional high temperature point at the anode side, helping to optimize heat distribution and lengthens the short-circuit time. At the same ON-state voltage ( ${V}_{ \mathrm{\scriptscriptstyle ON}}$ ) and 300 K, the ${E}_{ \mathrm{\scriptscriptstyle OFF}}$ of PT LIGBT is 65.6% and 50.2% lower than that of N-drift Con. LIGBT and LIGBT with CS layer (CS LIGBT), respectively. The PT LIGBT improves the short-circuit time by 12% compared with that of the CS LIGBT.