A trench-gate field stop insulated gate bipolar transistor (TFS-IGBT) with a novel hybrid p + /n collector structure is proposed to enhance the trade-off relationship between the on-state voltage drop (V on ) and the turn-off energy loss (E off ). The proposed hybrid collector structure consists of a p + /n layer between the p + collector and the field stop layer. During turn-on, the p + regions in the hybrid p + /n layer provide high carrier injection efficiency. During turn-off transient, the n-regions in the hybrid p + /n collector provide fast carrier extraction paths for holes. 2-D numerical simulations comparing a conventional TFS-IGBT, an injection efficiency controlled IGBT with the proposed hybrid p + /n collector TFS-IGBT (HC-IGBT) having similar device structures show that for a 1.2 kV rating and with V on at 1.5 V, the HC-IGBT has an advantage in E off reduction by 69% and 22%, respectively. Finally, backside mask alignment is not needed for fabricating the proposed hybrid p + /n collector structure. INDEX TERMS Hybrid p + /n collector, insulated gate bipolar transistor, on-state voltage drop, turn-off energy loss. KUI MA (M'17) received the B.S. and Ph.D. degrees in microelectronics and solid-state electronics from the