High power density and large voltage swing of enhancement-mode Al_0.5Ga_0.5As/InGaAs pseudomorphic high electron mobility transistor for 3.5 V L-band applications

A high power density and a large voltage swing of Al_0.5Ga_0.5As/InGaAs enhancement-mode pseudomorphic high electron mobility transistor (pHEMTs) operated under V_ds = 3.5 V for L-band application have been achieved using a high-uniformity and high-selectivity BCl₃+CHF₃ gas mixture. In this study, we improve the current density and the gate voltage operation region of the device by increasing the Al mole fraction of Al_xGa_1-xAs to x = 0.5. The developed 1.0-μm-long and 1 mm-wide gate FETs exhibit V_th = +0.24 V and I_max of 286 mA/mm. The maximum output power under a 1.9 GHz operation is 95 mW/ mm, with a linear power gain of 18.7 dB, and a power-added efficiency of 60%. These characteristics demonstrate that E-pHEMTs have great potential for using in microwave power device applications.