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 of In 0.7 Ga 0.3 As and 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 (I on ) gam of 20% is observed in the In 0.7 Ga 0.3 As QWFET over the strained Si nMOSFET at (V g - V t ) = 0.3 V, V ds = 0.5 V, and matched I off , despite higher external resistance and large gate-to-channel thickness. To understand the gain in I on , the effective carrier velocities (v eff ) near the source-end are extracted and it is observed that at constant (V g - V t ) = 0.3 V and V ds = 0.5 V, the v eff of In 0.7 Ga 0.3 As and InSb QWFETs are 4-5times higher than that of strained silicon (Si) nMOSFETs due to the lower effective carrier mass in the QWFETs. The product of v eff and charge density (n s ), which is a measure of "intrinsic" device characteristics, for the QWFETs is 50%-70% higher than strained Si at low-voltage operation despite lower ns in QWFETs. Calibrated simulations of In 0.7 Ga 0.3 As QWFETs with reduced gate-to-channel thickness and external resistance matched to the strained Si nMOSFET suggest that the higher v eff will result in more than 80% I on increase over strained Si nMOSFETs at V ds = 0.5 V, (V g - V t ) = 0.3 V, and matched I off , thus showing promise for future high-speed and low-power logic applications.