RF Breakdown and Large-Signal Modeling of AlGaN/GaN HFET's

HFET's fabricated from nitride-based wide bandgap semiconductors can produce RF output power greater than an order of magnitude compared to devices fabricated from traditional semiconductors such as GaAs and InP. Nitride-based HFET's can support drain bias voltages in the range of 40-50 V, and have been biased as high as 120 V using device designs that make use of field-plate technology. However, the RF power produced by these devices is still limited by breakdown phenomena. Breakdown can occur at the gate electrode on the drain side due to a tunnel leakage mechanism, and by RF breakdown in the conducting channel. In this work it is demonstrated that RF breakdown in the conducting channel is the primary mechanism limiting the RF power performance of these devices. Gate leakage current under RF drive produces reliability degradation. A new large signal model that includes RF breakdown is proposed, and it is demonstrated that the new model produces excellent agreement with experimental data