Ultra low noise characteristics of AlGaAs/InGaAs/GaAs pseudomorphic HEMT's with wide head T-shaped gate

The fully passivated low noise AlGaAs/InGaAs/GaAs pseudomorphic (PM) HEMT with 0.13 μm T-shaped gate was fabricated using dose split electron beam lithography method (DSM). This device exhibited low noise figures of 0.31 and 0.45 dB at 12 and 18 GHz, respectively. These noise figures are the lowest value ever reported for the GaAs based HEMT's. These results are attributed to the extremely low gate resistance which results from wide head T-shaped gate having the higher ratio more than 10 of gate head length to gate footprint.