Enhancement-Mode GaAs MOSFETs With an $\hbox{In}_{0.3} \hbox{Ga}_{0.7}\hbox{As}$ Channel, a Mobility of Over 5000 $ \hbox{cm}^{2}/\hbox{V} \cdot \hbox{s}$, and Transconductance of Over 475 $\mu\hbox{S}/\mu\hbox{m}$

Abstract

We present metal-gate high-k-dielectric enhancement-mode (e-mode) III-V MOSFETs with the highest reported effective mobility and transconductance to date. The devices employ a GaGdO high-k (k = 20) gate stack, a Pt gate, and a delta-doped InGaAs/AlGaAs/GaAs hetero-structure. Typical 1-mum gate length device figures of merit are given as follows: saturation drive current, I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d,sat</sub> = 407 muA/mum; threshold voltage, V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> = +0.26 V; maximum extrinsic transconductance, g <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> = 477 muS/mum (the highest reported to date for a III-V MOSFET); gate leakage current, I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> = 30 pA; subthreshold swing, S = 102 mV/dec; on resistance, R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</sub> = 1920 Omega-mum; I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</sub> ratio = 6.3 x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> ; and output conductance, g <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> = 11 mS/mm. A peak electron mobility of 5230 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /V. s was extracted from low-drain-bias measurements of 20 mum long-channel devices, which, to the authors' best knowledge, is the highest mobility extracted from any e-mode MOSFET. These transport and device data are highly encouraging for future high-performance n-channel complementary metal-oxide-semiconductor solutions based on III-V MOSFETs.