Influence of threading dislocation on on-resistance and breakdown phenomena of vertical GaN p-n junction diodes

The correlation between current-voltage (I-V) characteristics and threading dislocations was evaluated using p-n junction diodes on high-quality GaN substrate with average threading dislocation density (TDD) ≦ 4 x 10⁵ cm^-2 by newly developed maskless 3D (M-3D) method. In forward I-V characteristics, it was found that the on-resistance (R_on) increases as the number of dislocations in the diode increases. This result indicates that reducing the number of dislocations is effective in improving the forward I-V characteristics. On the other hand, in reverse I-V characteristics, it was found that there was no clear correlation between the breakdown voltage (V_B) and the number of dislocations. Also, the p-n diode's destruction point and the dislocation position did not match in almost all of the measured p-n diodes. These results suggest that the dislocation affects very little on V_B and the p-n diode destruction. (author)