Ga/sub 0.51/In/sub 0.49/P/In/sub 0.15/Ga/sub 0.85/As/GaAs pseudomorphic doped-channel FET with high-current density and high-breakdown voltage

Ga/sub 0.51/In/sub 0.49/P/In/sub 0.15/Ga/sub 0.85/As/GaAs pseudomorphic doped-channel FETs exhibiting excellent DC and microwave characteristics were successfully fabricated. A high peak transconductance of 350 mS/mm, a high gate-drain breakdown voltage of 31 V and a high maximum current density (575 mA/mm) were achieved. These results demonstrate that high transconductance and high breakdown voltage could be attained by using In/sub 0.15/Ga/sub 0.85/As and Ga/sub 0.51/In/sub 0.49/P as the channel and insulator materials, respectively. We also measured a high-current gain cut-off frequency f
_T
of 23.3 GHz and a high maximum oscillation frequency f
_max
of 50.8 GHz for a 1-μm gate length device at 300 K. RF values where higher than those of other works of InGaAs channel pseudomorphic doped-channel FETs (DCFETs), high electron mobility transistors (HEMTs), and heterostructure FETs (HFETs) with the same gate length and were mainly attributed to higher transconductance due to higher mobility, while the DC values were comparable with the other works. The above results suggested that Ga/sub 0.51/In/sub 0.49/P/In/sub 0.15/Ga/sub 0.85/As/GaAs doped channel FET's were were very suitable for microwave high power device application.