IGBTs working in the NDR region of their I-V characteristics

Abstract

This paper demonstrates the detailed work on high voltage IGBTs using simulations and experiments. The current-voltage characteristics were measured up to the break through point in forward bias operating region at two different temperatures for a 50 A/4.5 kV rated IGBT chip. The experimentally measured data were in good agreement with the simulation results. It was also shown that the IGBTs are able to clamp high collector-emitter voltages although a low gate turn-off resistor in combination with a high parasitic inductance was applied. Uniform 4-cell and 8-cell IGBT models were created into the TCAD device simulator to conduct an investigation. An engendered filamentation behaviour during short-circuit turn-off was briefly reviewed using isothermal as well as thermal simulations and semiconductor approaches for development of filaments. The current filament inside the active cells of the IGBT is considered as one of the possible destruction mechanism for the device failure.

Al modification as indicator of current filaments in IGBTs under repetitive SC operation

“…To understand the behaviour of the IGBT under SC operation, at first the static I C – V CE characteristics at different gate voltages were measured for two different temperatures. The measurement method of the complete I–V characteristics was explained in [18] up to 15 V V GE . In this work, the measurements were performed for the gate voltages up to 35 V. The measured destructive boundary line was introduced in the same plot to visualise the non‐operational regions in SC for both temperatures.…”

“…The parameters in the numerator for (1) were extracted from the oscilloscope data that gives the value for E SC . For parameters in the denominator were taken from the literature [13] considering the temperature dependency [18]. From the graphs, it appears that Δ T SC is <10 K for the gate voltages up to 15 V. However, it increases significantly for higher V GE and V CE .…”