Effect of AlN Spacer on the AlGaN/GaN HEMT Device Performance at Millimeter-wave Frequencies

Abstract

The effect of the AlN spacer on the performance of AlGaN/GaN HEMT devices at 38 GHz is experimentally investigated. The measurement results revealed that the device with spacer showed superior performance in terms of the maximum drain current. RF wise, substantial improvement in the cut-off frequency and the maximum oscillation frequency was also observed for devices with spacer. A saturated output power density of 4.21 W/mm with 35.02% power-added efficiency (PAE) at 38 GHz were achieved for device with 70nm gate length.