Submicron RIE recessed InGaP/InGaAs doped-channel FETs

High performance submicron In_0.49Ga_0.51P/In_0.15Ga_0.85As doped-channel heterostructure field effect transistors (HFETs) have been developed and characterized. In order to achieve a high uniformity of device characteristics crossing the wafer, BCl₃+CHF₃ reactive ion etching technology in gate-recessed process is applied to fabricate the InGaP/InGaAs doped-channel FETs. The unity current gain cut-off frequency (f_T), maximum frequency of oscillation (f_max), and threshold voltage have been investigated versus the gate-length. The improved microwave performance in smaller gate-length devices is mainly associated with the reduction of the input capacitance. The 0.2 × 200-μm² gate-dimension DCFET exhibits a saturated P_out of 18.9 dBm, a power density of 388 mW/mm, a PAE of 35%, and an associated gain of 14 dB at 2.4 GHz.