D V/d t effect in high-voltage (1.5 kV) 4H–SiC thyristors

Abstract

The switching of high-voltage (1.5 kV) 4H–SiC gate turn-off thyristors (GTOs) by the d V/d t effect has been studied in the temperature range from 300 to 504 K. At a 30 ns rise time of the forward bias V( t), the characteristic bias at which the structure under investigation can be switched on by the d V/d t effect decreases steadily from 289 V at room temperature (d V/d t ∼ 9.7 kV/μs) to 137 V at T = 504 K. The characteristic critical charge per unit area, Q cr, equal to 1.9 × 10 −7 C/cm 2 at room temperature, also decreases steadily as the temperature increases. The main physical mechanisms that contribute to Q cr formation and the temperature dependence of the critical charge are qualitatively analyzed. The influence exerted by two-dimensional processes on the d V/d t switching is examined by making analytical estimates and using a computer simulation. The results obtained agree well with experimental data.