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We report on GaN microwave varactors with capacitively coupled isolated electrodes. Metal-insulator-semiconductor (MIS) varactors have 4-5 orders of magni-tude lower leakage currents than similar devices with Schottky contacts. Low leakage capacitively coupled contacts enable microwave switches and power limiters with low loss, high RF power and excellent temperature stability up to at least 200 °C. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We report on a design of GaN based HFET with a low-conducting layer (LCL) coating. The LCL coating dramatically improves the electric field uniformity and increases the breakdown voltage. A major advantage is consistent control of the breakdown characteristics, which is expected to dramatically improve yield and reliability. Initial experimental studies demonstrated a three-fold increase in the breakdown voltage compared with conventional HFETs. The LCL also leads to a much more uniform underlying channel depletion evidenced by a significantly lower HFET channel capacitance in the off state for the HFET based RF switches. This results in a lower loss and higher isolation. Another advantage is a faster transient enabled by LCL, which should improve efficiency and reduce loss for power HFET switches.(© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The novel HFET design using perforated channel region under the gate reduces drain and source parasitic resistances due to the current spreading effect in the source-gate and gate–drain regions. Demonstrated results for AlGaN/GaN HFET show that the RONCG time constant reduces around two times using simple and robust perforated channel device processing. These results are especially important for new generations of power switching transistors. [ABSTRACT FROM AUTHOR]