High-performance, low-noise enhancement-mode pseudomorphic high-electron-mobility transistor with gate recession by citric acid/hydrogen peroxide selective etching

An enhancement-mode pseudomorphic high-electron-mobility transistor (E-PHEMT) using a citric acid/hydrogen peroxide etching solution for gate recession is developed. The etch selectivity between GaAs and Al_0.2Ga_0.8As is more than 165 at 22 °C, while the maximum transconductance for the fabricated device with the gate dimension of 160×0.25 μm² reaches 502 mS/mm at V_ds=2.7 V. Furthermore, at 12 GHz, the 1 dB compression output power and gain can reach 13.2 dB m and 17.9 dB, respectively. Operating at 12 GHz, the minimum noise figure at the bias conditions of V_ds=2 V and I_ds=11 mA decreases to 0.45 dB with the associated gain of 12.95 dB, which is comparable to, or even better than that of, reported low-noise depletion- or enhancement-mode PHEMT devices. The standard deviation of the pinch-off voltage for the E-PHEMT across a 4 in. diameter wafer could be as low as 50 mV.