Carrier Transport in High-Mobility III–V Quantum-Well Transistors and Performance Impact for High-Speed Low-Power Logic Applications

DC and high-frequency device characteristics ofIn0.7 Ga0.3Asand InSb quantum-well field-effect transistors (QWFETs) are measured and benchmarked against state-of-the-art strained silicon (Si) nMOSFET devices, all measured on the same test bench. Saturation current(Iₒₙ)gain of 20% is observed in theIn0.7Ga0.3AsQWFET over the strained Si nMOSFET at(Vg - Vₜ) = 0.3\ V,Vds = 0.5\ V, and matchedIoff, despite higher external resistance and large gate-to-channel thickness. To understand the gain inIₒₙ, the effective carrier velocities(νeff)near the source-end are extracted and it is observed that at constant(Vg - Vₜ) = 0.3\ VandVds = 0.5\ V, theνeffofIn0.7Ga0.3Asand InSb QWFETs are 4–5×higher than that of strained silicon (Si) nMOSFETs due to the lower effective carrier mass in the QWFETs. The product ofνeffand charge density(nₛ), which is a measure of “intrinsic” device characteristics, for the QWFETs is 50%–70% higher than strained Si at low-voltage operation despite lowernₛin QWFETs. Calibrated simulations ofIn0.7Ga0.3AsQWFETs with reduced gate-to-channel thickness and external resistance matched to the strained Si nMOSFET suggest that the higherνeffwill result in more than 80%Iₒₙincrease over strained Si nMOSFETs atVds = 0.5\ V,(Vg - Vₜ) = 0.3\ V, and matchedIoff, thus showing promise for future high-speed and low-power logic applications.