Effect of forward current stress on low frequency noise in 4H–SiC p-n junctions

Abstract

We report on the effect of forward current stress on the low frequency noise in the 4H–SiC rectifier p+-n diodes rated at 20 and 10 kV. The 4H–SiC diodes with 20 kV blocking voltage were the most sensitive to the forward current stress. Even the stress by the current density j=13 A/cm2 for 30 min led to a noticeable increase in the forward voltage drop and changes in the noise spectra. The stress decreased the level of the 1/f noise but led to the appearance of the burst noise. Stress at higher current densities (50 A/cm2) led to the disappearance of the burst noise and to a further increase in the forward voltage drop. Diodes with 10 kV blocking capability were more resistant to the forward current stress. However, they also demonstrated a decrease in the 1/f noise as a result of the 60 min stress at j=100 A/cm2.

Thermal Behavior of SiC Power Diodes

“…Nevertheless, the state-of-the-art SiC PiN diodes include that reported by Cree (6) with a forward voltage of 3.2 V at 180 A (100 A/cm 2 ), capable of blocking 4.5 kV with a reverse leakage current of 1 µA. SiC PiN diodes will be relevant for breakdown voltages over 3 kV and SiC PiN diodes with a blocking capability up to 20 kV have been demonstrated (1,7). The increase in blocking voltage is the future trend in (PiN) SiC diodes (8), which are supported with investigations and developments on Stacking Faults (SFs) free SiC wafers.…”

Low Frequency Noise as a tool to study degradation processes in 4H-SiC p-n junctions

“…DC current component is not represented in graph (after[7]). As a result of a higher current stress (j = 50A/cm 2 ) the burst noise disappeared and the level of the 1/f noise decreased.Diodes with 10kV blocking capability being more resistant to the forward current stress, also demonstrated a decrease of the 1/f noise as a result of the 60 min stress at j = 100ACurrent dependences of noise at frequency of analysis f = 10 Hz for 10kV diode.…”

“…As a result of a higher current stress (j = 50A/cm 2 ) the burst noise disappeared and the level of the 1/f noise decreased.Diodes with 10kV blocking capability being more resistant to the forward current stress, also demonstrated a decrease of the 1/f noise as a result of the 60 min stress at j = 100ACurrent dependences of noise at frequency of analysis f = 10 Hz for 10kV diode. Squares and triangles represent result for the virgin diode and the diode after 60 min degradation at j = 100 A/cm 2 ,respectively(after[7]). …”

“…The decrease of noise during the degradation is an unusual behavior, which is rarely observed in semiconductor devices (see ref [6], for example). This decrease of noise in SiC diodes might be explained by stacking faults generated during current stress serving as a sink for the defects responsible for 1/f noise [7].…”