Interest of 0.15 μm gate length InGaAs/InP composite channel HEMTs for millimeter-wave MMIC amplifiers

This paper outlines the use of an InGaAs/InP channel allows to reduce drastically impact ionisation effects and consequently output conductance of the device: 85 mS/mm for a composite channel compared to 145 mS/mm for the conventional channel. Using a composite channel, device transconductance is enhanced from 1 S/mm to 1.2 S/mm and cut-off frequency F_MAX increases by 50%. Thus a 0.15 μm gate length InGaAs/lnP composite channel HEMT shows a current gain cut-off frequency F_T of 151 GHz and a maximum unilateral gain cut-off frequency F_MAX of 225 GHz. The comparison of passivated and non-passivated devices highlights the influence of the feedback capacitance on RF performance. 0.15 μm gate length InGaAs/InP/InP n+ composite channel HEMTs have also been fabricated. Devices exhibit state of the art performance at 60 GHz, with an output power density of 350 mW/mm, 12% power-added-efficiency (PAE) and 6.2 dB of linear gain