In this work, the design, fabrication, and testing of improved, high power 4H-SiC merged p-i-n/Schottky(MPS) diodes, in the 600-1300 V voltage range, are described. Both DC and transient test results are presented. The diodes were designed with a multi-step junction termination extension (MJTE) to improve the blocking voltage. The MJTE design allows full utilization of the superior breakdown properties of SiC. At 600 V, the highest forward current capability of a packaged MPS diode showed a current of 50 A at 2 V and 140 A at 4 V. At 1300 V, the current was 4 A at 2 V and 10 A at 4 V. In addition, the SiC MPS diode reverse voltage showed excellent suppression of the Schottky leakage current at temperatures up to 250 degreesC. The transient properties were measured with an inductively loaded halfbridge inverter circuit at high current and high temperatures (high-T). Results showed that the replacement of Si freewheeling diodes by SiC diodes results in far less storage charge in the diodes and substantial reduction in diode turn-off energy loss, especially at high-T. Switching measurements at currents up to 230 A compared a SiC MPS and a state-of-the-art Si diode; the MPS showed a 47% energy loss reduction at room temperature and 84% at 200 degreesC. The IGBT energy loss reduction, when using an MPS diode, was 15% at room temperature and 45% at 150 degreesC. The use of MPS diodes should result in improved efficiency when used in power electronics applications. (C) 2002 Elsevier Science Ltd. All rights reserved.