Improved high-temperature characteristics of a symmetrically graded AlGaAs/InxGa1−xAs/AlGaAs pHEMT

Abstract

This work investigates the superior high-temperature and high-linearity characteristics of a double δ-doped AlGaAs/InxGa1−xAs/AlGaAs pseudomorphic high electron mobility transistor (pHEMT) with a symmetrically linearly graded InxGa1−xAs channel and a wide energy gap AlGaAs barrier. Distinguished high-temperature device characteristics are presented, including an extrinsic transconductance (gm,max) of 182 (223) mS mm−1, a drain–source saturation current density (IDSS) 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 (Av) of 505 (658) and a reverse breakdown voltage (BVGD) of −24.1 (−31.2) V at 500 (300) K, respectively, with gate dimensions of 0.65 × 200 µm2. In addition, the device demonstrates a superior stable thermal threshold coefficient (∂Vth/∂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 (ft) of over 20 GHz. Consequently, the proposed device shows good potential for high-temperature and high-linearity circuit applications.