Effects of Drift Layer Thicknesses in Reverse Conduction Mechanism on Vertical GaN-on-GaN SBDs grown by MOCVD

Effect of drift layer thicknesses (DLT) (2, 15 and $30 \mu m)$ in reverse current conduction mechanisms of vertical GaN-on-GaN Schottky Barrier Diodes grown MOCVD has been investigated for the first time. The conduction mechanism is changing from thermionic field emission (TFE) to thermionic emission (TE) when the DLT of GaN increases. The SBDs with DLT of $2 \mu m$ and $30 \mu m$ exhibit TFE through PooleFrenkel emission and TE, respectively. However, the SBDs with DLT of $15 \mu m$ exhibit both TFE and TE. Activation energy $(E_{a})$ of traps was also calculated to be 0.69 eV for $2 \mu m$, 0.38 for $15 \mu m$ and 0.4 eV for $30 \mu m$ respectively. $E_{a}$ of 0.69 eV and 0.4 eV could be associated with screw threading dislocations and the presence of Mg in the grown drift layer, respectively.