SiX2 (X = S, Se) Nanowire Gate-All-Around MOSFETs for Sub-5 nm Applications.

The gate-all-around (GAA) field-effect transistor (FET) holds great potential to support next-generation integrated circuits. Nanowires such as carbon nanotubes (CNTs) are one important category of channel materials in GAA FETs. Based on first-principles investigations, we propose that SiX2 (X = S, Se) nanowires are promising channel materials that can significantly elevate the performance of GAA FETs. The sub-5 nm SiX2 (X = S, Se) nanowire GAA FETs exhibit excellent ballistic transport properties that meet the requirements of the 2013 International Technology Roadmap for Semiconductors (ITRS). Compared to CNTs, they are also advantageous or at least comparable in terms of gate controllability, device dimensions, etc. Importantly, SiSe2 GAA FETs show superb gate controllability due to the ultralow minimum subthreshold swing (SSmin) that breaks "Boltzmann's tyranny". Moreover, the energy-delay product (EDP) of SiX2 GAA FETs is significantly lower than that of the CNT FETs. These features make SiX2 nanowires ideal channel material in the sub-5 nm GAA FET devices.

Impact of uniaxial strain on the electronic and transport properties of monolayer α-GeTe.

Density functional theory calculations are performed to explore the electronic and transport properties of monolayer α-GeTe under uniaxial strain. It is found that monolayer α-GeTe has an indirect band gap of 1.75 eV and exhibits worthwhile anisotropy along with high electron mobility. The electron mobilities reach 1974 cm2 · V-1 · s-1 and 1442 cm2 · V-1 · s-1 along the zigzag and armchair directions, respectively. When uniaxial strain is applied, our results show an appreciable strain sensitivity of electron mobility. The electron mobility dramatically increases by an order of magnitude around a special strain due to the shifts of conduction band minimum. In addition, we also construct a double gate tunneling field effect transistor (TFET) with a channel of monolayer α-GeTe. The steeper sub-threshold swing and higher ON/OFF ratio are observed by applying tensile strain to the channel. As a result, it indicates that the appropriate strain can significantly improve the performance of α-GeTe TFETs.