Investigation Of Gate Leakage Current Mechanism In Algan/Gan High-Electron-Mobility Transistors With Sputtered Tin

The gate leakage current mechanism of AlGaN/GaN Schottky barrier diodes (SBDs) and high-electron-mobility transistors (HEMTs) with sputtered TiN is systematically investigated. The reverse leakage current (J(R)) of TiN SBDs increases exponentially with the increase of reverse voltage (V-R) from 0 to -3.2V (Reg. I). This conduction behavior is dominated by Poole-Frenkel emission from TiN through an interface state of 0.53 eV to the conductive dislocation-related continuum states. The obtained interface state of 0.53 eV may be due to the plasma damage to the surface of the AlGaN/GaN HEMT structure during the TiN sputtering. When the TiN SBDs are biased with -20< V-R < -3.2V, J(R) saturated due to the depletion of the 2-dimensional electron gas (2DEG) channel (Reg. II). This conduction behavior is dominated by the trap-assisted tunneling through the interface state at similar to 0.115 eV above the Fermi level. The three terminal OFF-state gate leakage current of AlGaN/GaN HEMTs exhibited an activation energy of 0.159 eV, which is in close agreement with the obtained interface state of similar to 0.115 eV from saturated J(R) (Reg. II) of the SBDs. The observation of the negative temperature coefficient (similar to 1.75 V/K) from the OFF-state breakdown voltage (at 1 mu A/mm) of AlGaN/GaN HEMTs is due to the trap-assisted tunneling mechanism, which is also well correlated with the conduction mechanism realized from the reverse leakage current of the SBDs. Published by AIP Publishing.