RF characteristics of 150-nm AlGaN/GaN high electron mobility transistors fabricated using i-line stepper lithography

This article reports radio frequency characteristics of 150-nm gate aluminum gallium nitride (AlGaN)/gallium nitride (GaN) high electron mobility transistors (HEMTs) fabricated using i-line stepper lithography and a thermal reflow technique. The authors have developed two different gate structures that were a field-plated gate using the lift-off process and a Y-shaped gate using the ion-milling process. Fabricated HEMTs using these different gate structures exhibited nearly equivalent DC characteristics. The field-plated gate device showed a unity current gain cutoff frequency (f(T)) of 35 GHz and a maximum oscillation frequency (f(max)) of 106 GHz, while the Y-shaped gate device showed f(T) of 36 GHz and f(max) of 115 GHz. The equivalent circuit analysis indicated a decrease in the gate-drain capacitance and the drain conductance is responsible for the improved f(max) in the Y-shaped gate device.

Automated summary

This article reports the radio frequency characteristics of 150-nm gate aluminum gallium nitride (AlGaN)/gallium nitride (GaN) high electron mobility transistors (HEMTs) fabricated using i-line stepper lithography and a thermal reflow technique. The authors have developed two different gate structures, a field-plated gate using the lift-off process and a Y-shaped gate using the ion-milling process. The HEMTs fabricated with these gate structures exhibited similar DC characteristics, but the Y-shaped gate device showed slightly better high-frequency performance.