Reverse Leakage Mechanism of Dislocation-Free GaN Vertical p-n Diodes

The reverse leakage mechanism of threading dislocation (TD)-free gallium nitride (GaN) vertical p-n diode was investigated in various temperature range, and it was compared with that of the p-n diode having a threading dislocation density (TDD) of around $10^{{6}}$ cm $^{-{2}}$ . The reverse leakage current was increased markedly by increasing the temperature from 400 K, the dominant mechanism was explained by thermionic and Poole-Frenkel emissions for TD-free and high-TDD p-n diodes, respectively. At high temperatures and electric fields, the leakage current of the high TDD p-n diode showed 2 times higher than the TD-free p-n diode. These results indicate that the performance of vertical GaN devices, especially when employed at high temperatures and electric fields, can be enhanced by removing TDs.