High Frequency Characteristics of AlInGaN HEMTs on Low Resistance Silicon for Millimeter-Wave Applications

This work demonstrates a high performance AlInGaN/AlN/GaN high electron mobility transistor grown on 150 mm p-type low resistance (resistivity ~20-100 ohm.cm) silicon substrate. Devices of Lgs/Lg/Lgd = 1/0.16/2 um and Lgs/Lg/Lgd = 1/0.16/4 um, show similar DC characteristics with IDSS of 893 mA/mm and 854 mA/mm, transconductance of 370 mS/mm and 375 mS/mm, Ron of 0.175 mohm-cm ² and 0.259 rnohm-cm ² , and three terminal off-state breakdown (BV) voltage of 69 V and 127 V respectively. Current gain cut-off frequency (fT) of 83 GHz and 63 GHz and power gain cut-off frequency (fmax) of 95 GHz and 77 GHz with a high Johnson's figure-of-merits (J-FOM) of 5.7 THz-V and 8.0 THz-V are achieved on the devices with gate to drain distance of 2 um and 4 um respectively. After de-embedding the substrate effect, the fmax of Lgd = 2 um device increases from 95 GHz to only 105 GHz, indicating the influence of substrate is limited in the epilayer structure used in this work. The fT and J-FOM are comparable or better than the reported values obtained on high resistance silicon, sapphire, and SiC substrates for devices with similar gate length.