Comparative study of ALD MoS₂ on high-k dielectrics for the fabrication of nanowire FETs

Field effect transistors (FETs) with layered MoS<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> channel need among other essential requirements a convenient gate dielectric. High-k dielectrics such as HfO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and Al<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> are good candidates not only to act as capacitor and electrical barrier but also to screen the Coulomb scattering from charged defects, which highly degrade the carrier mobility. However, the MoS<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> synthesis on these dielectrics realized at the wafer scale remains a difficult task. In this work, we report the impact of conventional SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> oxide and HfO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and Al<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> high-k dielectrics on the morphology and physicochemical properties of the ALD-based MoS<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> film. ALD approach enables a precise thickness controllability and a high uniformity on 200 mm substrates. Then, functional back-gated FETs with MoS<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> nanowire channels, down to 50 nm width, were fabricated and electrically characterized at the 200 mm wafer scale, with promising electrical results.