Demonstration of Schottky Barrier NMOS Transistors With Erbium Silicided Source/Drain and Silicon Nanowire Channel

Abstract

We have fabricated silicon nanowire N-MOSFETs using erbium disilicide (ErSi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2-x</sub> ) in a Schottky source/drain back-gated architecture. Although the subthreshold swing (~180 mV/dec) and drain-induced barrier lowering (~500 mV/V) are high due thick BOX as gate oxide, the fabricated Schottky transistors show acceptable drive current ~900 muA/mum and high 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 (~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> ). This is attributed to the improved carrier injection as a result of low Schottky barrier height (Phi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> ) of ErSi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2-x</sub> /n - Si(~0.3 eV) and the nanometer-sized (~8 nm) Schottky junction. The carrier transport is found to be dominated by the metal-semiconductor interface instead of the channel body speculated from the channel length independent behavior of the devices. Furthermore, the transistors exhibit ambipolar characteristics, which are modeled using thermionic/thermionic-field emission for positive and thermionic-field emission for negative gate biases.