Depth Distribution of Defects in SiC PiN Diodes Formed Using Ion Implantation or Epitaxial Growth

Abstract

In the development of 4H‐SiC bipolar devices, defect generation during the fabrication process is an important issue for maintaining a long carrier lifetime in the drift layers. Herein, two 4H‐SiC PiN diode structures are produced with a p‐type layer fabricated through epitaxial growth or Al ion implantation; and the current–voltage characteristics and defect distribution observed using deep‐level transient spectroscopy and cathodoluminescence (CL) are compared. The PiN diode fabricated through ion implantation shows higher deep‐level concentrations even at a drift layer depth of ≈6 μm from the junction. In addition, the concentrations at the deep levels decrease with the depth, as does the CL intensity originating from defects. Therefore, defects induced through Al‐ion implantation are distributed into a drift layer with a gradual decrease in the concentration along the depth. These results suggest that drift layers in 4H‐SiC bipolar devices should be fabricated in regions far from the Al‐ion‐implanted regions to induce an efficient conductivity modulation.

Effects of ion implantation process on defect distribution in SiC SJ-MOSFET

“…The other peaks are similar to those observed in the electron-irradiated or Al-implanted p-type 4H-SiC. 26,33)…”

“…© 2023 The Japan Society of Applied Physics be diffused from the implanted p-type columns to the n-type columns. 26) When compared with the samples implanted at 500 °C, Semi-SJ n-epi RT shows a widely distributed L 1 luminescence in the entire multi-epi layer, and only a slight difference is observed between the n-type and implanted ptype columns as shown in Fig. 3(c).…”

“…Although these additional DLTS peaks would be due to wider measurement regions in the p-type side in the SJ structure compared with the Non-SJ structure, the deep levels observed in the p-type side would be caused by the Al ion implantation because of similarity to the parameters for deep levels in electron irradiated or Al-implanted p-type 4H-SiC. 26,33) Given the correspondence of the observed DLTS peaks with those reported for p-type 4H-SiC, the deep levels observed in the study should be located near the valence band in energy and spatially within the p-type regions. This suggests that the Al ion implantation process induces defects with L 1 line luminescence and deep levels acting as recombination centers.…”

“…Furthermore, we observed deep levels and defect distributions generated by ion implantation in SiC SJ-MOSFETs via deep-level transient spectroscopy (DLTS) and cathodoluminescence (CL) methods. 26)…”