Modified model of gate leakage currents in AlGaN/GaN HEMTs

It has been reported that the gate leakage currents are described by Frenkel-Poole emission (FPE) model, at the temperatures higher than 250 K. However, the gate leakage currents of our passivated devices do not accord with the FPE model. Therefore, a modified FPE model is developed in which an additional leakage current, besides the gate (I_II), is added. Based on the samples with different passivations, the I_II caused by a large number of surface traps is separated from total gate currents, and is found to be linear with respect to (φ_B-V_g)^0.5. Compared with these from the FPE model, the calculated results from the modified model agree well with the I_g-V_g measurements at temperatures ranging from 295 K to 475 K.