The critical charge density in 2.6 kV 4H-SiC thyristors, n(cr), has been investigated in the temperature range from 300 to 500 K using gate-controlled switching and pulsed optical triggering. The n(cr) values furnished by these different techniques are in reasonable agreement. The nc, decreases monotonically from n(cr) similar to 10(16) cm(-3) at T = 300 K to n(cr) similar to 10(14) cm(-3) at T = 500 K. At room temperature, the n(cr) value found in this study for high-voltage SiC thyristors is an order of magnitude larger than that in low-voltage SiC thyristors with breakover voltage of 400 V, and is of the same order as that in the high-voltage power Si thyristors. (C) 2002 Elsevier Science Ltd. All rights reserved.