Temperature dependence of forward characteristics for ultrahigh-voltage SiC p–i–n diodes with a long carrier lifetime

Abstract

Forward characteristics of ultrahigh-voltage 4H-SiC p-i-n diodes having four different n % -layer (i-layer) thicknesses from 48 to 198 µm were investigated in the temperature range from room temperature to 573 K. After enhancement of carrier lifetimes in i-layers, nearly ideal forward characteristics (differential on-resistance = 1.1-5.5 mΩ cm 2 at 100 A/cm 2 ) were obtained at room temperature. The forward voltage drop decreased with temperature, which is consistent with the temperature dependence of junction voltage. The differential on-resistance exhibited a slight increase at elevated temperatures, which can mainly be ascribed to the increase in substrate resistance.

Promise and Challenges of High-Voltage SiC Bipolar Power Devices

“…This result is consistent with a report on 4.5 kV SiC pin diodes formed by implantation [42]. When the carrier lifetime in the i-layer is long enough, the differential on-resistance of a pin diode is low and its temperature dependence is small [9], which is the major reason why the bipolar on-resistance of the epitaxial MPS diode in this study was much lower and showed the small temperature dependence. However, the increase of carrier lifetime at elevated temperature significantly contributes to the conductivity modulation and to decrease of the differential on-resistance when the carrier lifetime is short, because the conductivity of more and more region inside the i-layer is modulated with increasing the temperature.…”

“…For ultrahigh-voltage (>10 kV) power devices, SiC bipolar devices are promising, because the resistance of the thick voltage-blocking layer can remarkably be reduced by the conductivity modulation effect, and the on-resistance exhibits a very small temperature dependence [9]. A drawback of bipolar devices is, of course, the slower switching speed and thereby the increased switching loss.…”

Low V F 4H-SiC N-i-P diodes using newly developed low-resistivity p-type substrates

“…The temperature dependence of the V F and R on,diff is strong, which is more similar to the characteristics of a N-i-P diode using a p-type epitaxial layer as the anode than a P-i-N diode using an n-type substrate as the cathode. 35,36) If we used maximum substrate resistivity of developed #2 in Fig. 3, 680 mΩ cm, and average remaining thickness of developed #2 after substrate grinding, 133 μm, the substrate resistance was estimated to be 9.0 mΩ cm 2 .…”