High uniformity enhancement- and depletion-mode InGaP/InGaAs pHEMTs using a selective succinic acid gate recess process

High uniformity enhancement-mode (E-mode) and depletion-mode (D-mode) InGaP/InGaAs pseudomorphic high electron mobility transistors (pHEMTs) have been developed on 6 inch GaAs substrate using a selective succinic acid gate recess process. The 0.5 νm long gate fingers of E-mode and D-mode pHEMTs are deposited simultaneously in this process simplification. The InGaP/InGaAs E-mode pHEMT exhibits a maximum drain-to-source current (I_ds) of 460 mA mm^-1, and a maximum transconductance (g_m) of 430 mS mm^-1. At 5.2 GHz operation, 216 mW mm^-1 power density, 40% power-added efficiency and a 0.81 dB minimum noise figure (NF _min) are also achieved for the E-mode device. In this study, D-mode pHEMTs are applied for a switch monolithic microwave integrated circuit which provides an insertion loss of -1.8 dB and isolation of -9.2 dB under 28 dBm input power (P_in) and 5.5 GHz operation. From these measured results, this uniform E/D-mode InGaP/InGaAs pHEMT technology exhibits a high potential for WLAN applications.