A Promising New n++-GaN/InAlN/GaN HEMT Concept for High-Frequency Applications

We study enhancement-mode n ++ -GaN/InAlN/GaN high electron mobility transistors (EHEMTs) by means of two-dimension al numerical device simulation. An introduction of a highly-doped GaN cap layer, which is remove d under the gate, was initially proposed for an improvement of the device performance by diminishing surface traps-related parasitic effects. Our new simulation results reveal that, unlikely to planar transistor structures, the extension of the gate depletion region with drain bias is kept restricted in the presence of an n ++ -GaN cap layer. This highly-scaled new device concept is very promising for ultra-high frequency performance.