Improved high-temperature characteristics of a symmetrically graded AlGaAs/In_xGa_1-xAs/AlGaAs pHEMT

This work investigates the superior high-temperature and high-linearity characteristics of a double δ-doped AlGaAs/In_xGa _1-xAs/AlGaAs pseudomorphic high electron mobility transistor (pHEMT) with a symmetrically linearly graded In_xGa_1-xAs channel and a wide energy gap AlGaAs barrier. Distinguished high-temperature device characteristics are presented, including an extrinsic transconductance (g _m,max) of 182 (223) mS mm^-1, a drain-source saturation current density (I_DSS) of 428 (524) mA mm^-1, an output conductance of 0.334 (0.352) mS mm^-1, a gate-voltage swing (GVS) of 1.45 (1.5) V, a voltage gain (A_v) of 505 (658) and a reverse breakdown voltage (BV_GD) of -24.1 (-31.2) V at 500 (300) K, respectively, with gate dimensions of 0.65 × 200 νm². In addition, the device demonstrates a superior stable thermal threshold coefficient (∂V_th/∂T) of -0.55 mV K^-1, a thermal GVS coefficient (∂GVS/∂T) of -0.25 mV K^-1 and a wide gate-bias range of 1.25 V for a unity-gain cut-off frequency (f_t) of over 20 GHz. Consequently, the proposed device shows good potential for high-temperature and high-linearity circuit applications.