Different structures of Reserve-Conducting Gate-Commutated\break Thyristor (RC-GCT) are considered in this paper. The non-punch-through and punch-through structures were recommended for blocking voltages of 2.5 kV and 4.5 kV, respectively. The photomasks were designed upon the high turn-off capability of GCT and the monolithic integration of GCT and free wheeling diode (FWD). For a large-diameter RC-GCT device with a high turn-off current capacity, FWD and GCT were designed at the center region and the outer part of wafer, respectively. Mixed mode simulation results using the ISE-TCAD simulators give turn-on and turn-off waveforms of the considered structures. A modified isolation structure between GCT and FWD is proposed for RC-GCT.