Yasuo Kito

Transmission electron microscope study of a threading dislocation with and its effect on leakage in a 4H–SiC MOSFET

Threading dislocations (TD’s) in a 4H-SiC MOSFET were characterized using transmission electron microscopy with special emphasis of their effects on leakage in a p–n junction. Two types of TD’s were identified; a threading near-screw dislocation (TnSD) with , and a threading mixed dislocation (TMD) with , the last of which has been found for the first time in this study. The TnSD show only negligibly small leakage, while TMD shows a large leakage. Origins of the difference in the degree of the leakage have been discussed.

Reducing Stacking Faults in Highly Doped N-Type 4H-SiC Crystal

We investigated a way of reducing the stacking fault (SF) density on a highly nitrogen (N) doped 4H-SiC crystal. SFs were generated at highly N doped crystal exceeding 4 x 1019 cm-3 and the density was increased with increasing N concentration. We found that Al co-doping had the potential to suppress this SF generation and was effective up to an N concentration of about 1 x 1021cm-3. This effect depended strongly on the Al concentration. We discussed the reason for the SF suppression effect of Al co-doping.