Study on the conduction mechanism of surface leakage current for AlGaN/GaN HEMTS under reverse gate bias

This paper focuses on the conduction mechanism of surface leakage for AlGaN/GaN HEMTs with SiN passivation. By utilizing the dual-gate structure, the surface leakage current can be exactly extracted. The surface leakage currents at different temperatures under the reverse gate bias have been measured accordingly. Base on the theoretical analysis of two-dimensional variable range hopping mechanism, it is observed that the experimental data have a good agreement with this mechanism. Therefore, it is concluded that the surface leakage current is induced by the electron hopping through the surface states around the Fermi level in AlGaN layer. Eventually, the activation energy of surface leakage has been extracted, which is around 0.083 eV.