Physical insights on transistors based on lateral heterostructures of monolayer and multilayer PtSe2 via Ab initio modelling of interfaces

Gaetano Calogero,Enrique G Marin,Giuseppe Iannaccone,Damiano Marian,Gianluca Fiori

doi:10.1038/s41598-021-98080-y

Gaetano Calogero, Enrique G Marin + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-98080-y

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Abstract

Lateral heterostructures (LH) of monolayer-multilayer regions of the same noble transition metal dichalcogenide, such as platinum diselenide (PtSe2), are promising options for the fabrication of efficient two-dimensional field-effect transistors (FETs), by exploiting the dependence of the energy gap on the number of layers and the intrinsically high quality of the heterojunctions. Key for future progress in this direction is understanding the effects of the physics of the lateral interfaces on far-from-equilibrium transport properties. In this work, a multi-scale approach to device simulation, capable to include ab-initio modelling of the interfaces in a computationally efficient way, is presented. As an application, p- and n-type monolayer-multilayer PtSe2 LH-FETs are investigated, considering design parameters such as channel length, number of layers and junction quality. The simulations suggest that such transistors can provide high performance in terms of subthreshold characteristics and switching behavior, and that a single channel device is not capable, even in the ballistic defectless limit, to satisfy the requirements of the semiconductor roadmap for the next decade, and that stacked channel devices would be required. It is shown how ab-initio modelling of interfaces provides a reliable physical description of charge displacements in their proximity, which can be crucial to correctly predict device transport properties, especially in presence of strong dipoles, mixed stoichiometries or imperfections.

Highlights

Lateral heterostructures (LH) of monolayer-multilayer regions of the same noble transition metal dichalcogenide, such as platinum diselenide (PtSe2), are promising options for the fabrication of efficient two-dimensional field-effect transistors (FETs), by exploiting the dependence of the energy gap on the number of layers and the intrinsically high quality of the heterojunctions
In order to demonstrate that including the Eon-site profile in the NEGF Hamiltonian is reliable, we compare in Fig. 4b the charge density difference (CDD) obtained with Density Functional Theory (DFT) for the 2L-1L LH and that obtained with NanoTCAD ViDES by self-consistently solving the electrostatics at equilibrium without external bias, and mapping ρ(x) = S−1
Hereafter we report on the performance prediction of a doublegated 4L-1L PtSe2 LH-FETs far from equilibrium, and the variations associated to the ab-initio modelling of the sharp and smooth interfaces