Physical mechanisms on the abnormal gate-leakage currents in pseudomorphic high electron mobility transistors

In this brief, we report a new observation on the abnormal gate-leakage current and associated physical mechanisms in packaged gallium arsenide (GaAs)-based n-channel pseudomorphic high electron mobility transistors (PHEMTs) with a gate length L=0.2 μm. Abnormal positive and negative humps in the gate current (I_G), as a function of the gate voltage, have been investigated at room temperature. Qualitative models for the positive and negative humps in the experimental I_G are proposed, combining physical mechanisms of thermionic emission, impact ionization, real-space-transfer (RST), and resonant tunneling through the alignment of quantized states in the InGaAs channel and the δ-doped AlGaAs donor layer. An experimental result is also provided for the anomalous I_G under large-drain bias and forward-gate bias.