Evidence of Poole-frenkel and Fowler-Nordheim tunneling transport mechanisms in leakage current of (Pd/Au)/Al0.22Ga0.78N/GaN heterostructures

Abstract

In this report, the gate leakage mechanism for AlGaN/GaN high electron mobility transistors (HEMTs) is consistently analyzed by means of temperature-dependent reverse gate current–voltage characteristics in the temperature range of 60–320 K. The gate leakage current of the AlGaN/GaN HEMT is studied by adjusting the experimental data using Poole–Frenkel (PF), and Fowler–Nordheim (FN) tunneling. In the temperature range of 200–325 K, the reverse bias leakage current is well dominated by a Frenkel-Poole emission model. The scenario describing the PF mechanism assumes that a defect level at φt = 0.45eV could be considered as an intermediate level through which carriers can transit to reach another level attributed to dislocations closer to conduction band. On the other hand, the FN mechanism seems to operate over the entire temperature range of 60–320 K and starts to dominate the gate leakage current due to triangular barrier formation.