Abstract
AbstractAs 2D materials (2DMs) gain the research limelight as a technological option for obtaining on‐demand printed low‐cost integrated circuits with reduced environmental impact, theoretical methods able to provide the necessary fabrication guidelines acquire fundamental importance. Here, a multiscale modeling technique is exploited to study electronic transport in devices consisting of a printed 2DM network of flakes. The approach implements a Monte Carlo scheme to generate the flake distribution. By means of ab initio density functional theory calculations together with non equilibrium Green's functions formalism, detailed physical insights on flake‐to‐flake transport mechanisms are provided. This later feeds a 3D drift‐diffusion and Poisson solution to compute self‐consistently transport and electrostatics in the device. The method is applied to MoS2 and graphene‐based dielectrically gated FETs, highlighting the impact of the structure density and variability on the mobility and sheet resistance. The prediction capability of the proposed approach is validated against electrical measurements of in‐house printed graphene conductive lines as a function of film thickness, demonstrating its strong potential as a guide for future experimental activity in the field.
Highlights
As 2D materials (2DMs) gain the research limelight as a technological option dispersions can be deposited layer-by-layer on a wide range of substrates to define for obtaining on-demand printed low-cost integrated circuits with reduced environmental impact, theoretical methods able to provide the necessary fabrication guidelines acquire fundamental importance
We have presented a simulation platform to study the electrical properties and behavior of field-effect transistor (FET) based on 2DM
We have exploited the multi-scale modeling approach combining different levels of abstraction in order to comprehend the electronic transport in micrometer-sized devices made of nanometric 2DM flakes
Summary
To exemplify the capabilities of the proposed multiscale approach as well as to provide guidelines regarding the main variables that determine electrical transport in 3D networks of 2D printed flakes, we have opted for a structure adapted from a 2D inkjet-printed FET.[1]. The different order of magnitude for the two materials can be expected due to the semiconducting electronic nature opposite to a semi-metallic one and their different anisotropic conductance In both cases, the trend follows a percolating-type performance: if we consider approximately FF = 0.3 as the threshold, it is possible to see an abrupt decrease in resistance from FF = 0.3–0.4, which continues (even though to a lesser extent) for even larger FF values. The predicted decaying trends for both materials highlight the impact of the FF on the device sheet resistance and draw attention to the necessity of having high flakes density in the inks so to avoid experimental realizations close to the percolating threshold This point, the sheet resistance decreases approaching the bulk values, and the improvements in the sheet resistance figures of merit are more incremental. The impact of the channel thickness is very dependent on the channel material: while the semi-metallic nature of graphene results in a proportional scaling of the current with the channel thickness, in MoS2 the current barely changes with it, as most of the conductive paths are determined by the region of the channel close to the gate terminal
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