Low noise characteristics of double-doped In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As power metamorphic HEMT on GaAs substrate with wide head T-shaped gate

The 0.2 /spl mu/m gate-length power MHEMTs with the wide head T-shaped gate are characterized for DC, microwave, and noise performance. The MHEMT device shows the DC output characteristics having an extrinsic transconductance of 700 mS/mm and a threshold voltage of -0.92 V. The f/sub T/ and f/sub max/ obtained for the 0.2 /spl mu/m /spl times/ 100 /spl mu/m MHEMT device are 120 GHz and 230 GHz, respectively. The MHEMTs exhibit the minimum noise figure, NF/sub min/, of 1.26 dB and associated gain of 8.6 dB at 30 GHz. The NF/sub min/ measured at 35 GHz is 1.45 dB with associated gain of 7.5 dB. This noise data is first reported for power MHEMT devices with InGaAs channel of 53% In. These excellent noise characteristics can be explained by the drastic reduction of gate resistance owing to the T-shaped gate with a wide head of about 1.2 /spl mu/m and the improved device performance.