Hole Transport in Strained $\hbox{Si}_{0.5} \hbox{Ge}_{0.5}$ QW-MOSFETs With $\langle\hbox{110}\rangle$ and $\langle\hbox{100}\rangle$ Channel Orientations

Abstract

Hole velocity and mobility are extracted from quantum-well (QW) biaxially strained Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> Ge <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> channel metal-oxide-semiconductor field-effect transistors (MOSFETs) on silicon-on-insulator wafers. Devices have been fabricated at sub-100-nm gate length with HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /TiN gate stacks. A significant hole mobility enhancement over the strained Si mobility curve is observed for QW MOSFETs. We also discuss the relationship between velocity and mobility of the strained SiGe channels with high Ge content for 〈100〉 and 〈110〉 crystal directions. Whereas the mobility increases by 18% for 〈100〉 with respect to 〈110〉, it translates into a modest 8% velocity increase.