Novel fabrication process for Si ₂ N ₄ passivated InAlAs/UnGaAs/InP HFETS

The process technology of fully passivated T-shaped 0.18 μm gate length InAlAs/GaAs/InP HFETs is described. Using material selective etchants, devices realised with this process yielded gate breakdown voltages in excess of 8 V and drain source breakdown voltages in excess of 8 V and drain source breakdown voltages in excess of 5 V. The excellent gate characteristics lead to a noise figure of 0.75 dB at 18 GHz with 13dB associated gain. The extrapolated maximum frequency of osciallation was determined to be fmax = 290 GHz