Dc and microwave noise characteristics of AlGaN/GaN HEMT with AlN and InGaN interlayers

High-performance Al_0.3Ga_0.7N/GaN high electron-mobility transistors (HEMTs) with 1 μm gate length have been simulated. The devices exhibited a transconductance of about 100 ms/mm at VDS = 9 V and a minimum noise figure (NF_min) of 0.79 dB at 10 GHz. Also we inserted a 1 nm AlN layer at the interface of Al_0.3Ga_0.7N/GaN as spacer layer. The AlN produces a larger conduction band offset (ΔEc), higher polarization charge and higher carrier density. Due to high carrier density and high mobility AlGaN/AlN/GaN HEMT shown higher transconductance of 165 mS/mm at VDS = 9 V and lower NF_min of 0.52 dB at 10 GHz than Al_0.3Ga_0.7N/GaN HEMT. For further improvement we inserted a 3 nm In_0.1Ga_0.9N layer at a location that is 6-nm away from the Al_0.3Ga_0.7N/GaN HEMT hetrointerface. The In_0.1Ga_0.9N causes high polarization charge which makes a high barrier potential and prevents carrier to go into substrate. Our calculation shown that Al_0.3Ga_0.7N/AlN/GaN/In_0.1Ga_0.9N/GaN DH-HEMT have higher transconductance of about 222 mS/mm at VDS = 9 V and lower NF_min of 0.42 dB at 10 GHz than AlGaN/AlN/GaN HEMT.