Electron-beam-induced current observed for dislocations in diffused 4H-SiC P–N diodes

Abstract

The electron-beam-induced current (EBIC) method was employed to investigate the electrical activity of dislocations in silicon carbide Schottky and diffused p–n diodes. Dislocations in Schottky diodes appear as dark spots with the EBIC current signal at the dislocations reduced with respect to the background. However, in p–n diodes, the same dislocations exhibited characteristic bright halos, with the EBIC current higher than that of the background. These bright halos were attributed to a nonuniform impurity distribution around dislocations caused by the high-temperature (∼2000 °C) diffusion process.

Observation of dislocations in diffused 4H–SiC p-i-n diodes by electron-beam induced current

“…11 It has been shown in an earlier work that at high magnification, the bright spots observed in the EBIC images have bright halos with inner dark spots. 12 This type of contrast was attributed to the depleted zones of impurities around dislocations due to the gettering effect. 13 Figure 1(b) shows the EBIC image of the same p-i-n diode as in Fig.…”

“…2 for zero bias. 12 At low-resolution scanning conducted in the present experiments, the contrast from the dark inner spot is smeared and the measured contrast profile is mostly defined by a bright halo signal corresponding to the central part of the defects. Figure 3 shows the maximum contrasts of specific defects (left scale) versus reverse bias voltage.…”

Effect of Trap Levels and Defect Inhomogeneities on Carrier Transport in SiC Crystals and Radiation Detectors

“…This confirms that indeed the effective activation energy values are given not by a number of carriers, but rather by the applied voltage, which modifies transport conditions in a network of potential barriers. Assuming that the applied voltage can modulate the effective barrier height by their thermal activation energy value until saturation is reached, and that all the barriers are connected in series, the mean dimensions of inhomogeneous regions can be evaluated as 1.5-3.8 µm, which is close to the real values [9]. Different properties of defects observed at lower and at higher temperatures are evidenced also by photocurrent temperature dependencies (Fig.…”

Carrier transport in SiC crystals and radiation detectors as affected by defect traps and inhomogeneities

“…It might be assumed that the voltage should change the effective barrier height by a value that is similar to its thermal activation energy. If the barriers are supposed to be connected in series, such evaluation gives that the mean dimensions of inhomogeneous regions should be 1.5-3.8 m, what is close to the real values [8]. Different defect properties are also evidenced by photocurrent behaviour (Fig.…”