A 60 GHz high power composite channel GaInAs/InP HEMT on InP substrate with LG=0.15 μm

We have improved power performance by studying three different GaInAs/InP composite channel structures. Also, different gate to drain extension devices have been processed. By using composite channel devices, we benefit from the better ionization threshold energy of InP compared to GaInAs (1.69 eV against 0.92 eV). The difference of conduction band offset between the two materials (ΔE_C=0.2 eV) makes possible electron transfer from GaInAs to InP layers with the same electronic properties. New process technologies have been applied to compare these structures. The gate current resulting from the impact ionization phenomena is reduced to 30 μA at V_DS=4.5 V for a large extension device, which constitute the best result among the three structures. Also, we improve power performances at 60 GHz by reducing the GaInAs channel width and substituting delta doping by bulk doping. The best device performance is 422 mW/mm at V_DS=3 V and V_GS=0.7 V