An AlN/Al_xGa_1-xN/GaN graded channel HEMT with enhanced power and linearity performance

In this work, an AlN/Al_xGa_1-xN/GaN graded channel HEMT (AlN. GC HEMT) with enhanced power and linearity performance has been proposed. With the adoption of a strong-polarized AlN barrier and a graded Al_xGa_1-xN channel, a current density of 1806 mA/mm and a transconductance (G_m) gate voltage swing (GVS-G_m) of 7 V were gained. At 3.6 GHz load pull measurements with a drain voltage (V_DS) of 8 V, the AlN. GC HEMT exhibited a maximum output power density (P_out) of 2.2 W/mm. Two-tone intermodulation distortion measurement further revealed an output third-order intercept point (OIP3) of 35.5 dBm and a corresponding linearity figure of merit (OIP3/P_DC) of 11.2 dB. The improved performance can be attributed to the hybrid 2DEG and 3DEG distribution in the channel, where the high density 2DEG contributes to a large output capacity, and the smooth 3DEG facilitates a sustained and stable charge accumulation with bias variation. These results indicate the potential of AlN. GC HEMT in 5G applications that target high power density and high linearity.