High-Performance Gate-First Epitaxial Ge n-MOSFETs on Si With $\hbox{LaAlO}_{3}$ Gate Dielectrics

Abstract

This brief presents high-performance Ge n-MOSFETs with good high-field mobility of 218 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /V · s at 0.5 MV/cm, low subthreshold swing (SS) of 108 mV/dec, small equivalent oxide thickness (EOT) of 1.6 nm, low 7 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> A/μm OFF-state leakage, small bias temperature instability of 31 mV at 1.2 V overdrive and 85°C, and full process compatibility with current very large-scale integration fabrication. These are one of the best SS and high-field mobility data among gate-first Ge n-MOSFETs using epitaxial Ge on 6-in Si wafer and proper high-κ LaAlO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> dielectric without using an interfacial layer. Using a different high-κ HfAlO gate dielectric, the Ge n-MOSFETs showed poor leakage, large flatband voltage shift, and degraded EOT.