[paper] SPICE Compact Model for Schottky-Barrier FETs

Sheikh Aamir Ahsan, Member, IEEE, Shivendra Kumar Singh, Chandan Yadav, Member, IEEE, Enrique G. Marín, Member, IEEE, Alexander Kloes, Senior Member, IEEE

and Mike Schwarz, Senior Member, IEEE

A Comprehensive Physics-Based Current–Voltage SPICE Compact Model 

for 2-D-Material-Based Top-Contact Bottom-Gated Schottky-Barrier FETs

IEEE Transactions on Electron Devices, vol. 67, no. 11, pp. 5188-5195, Nov. 2020

DOI: 10.1109/TED.2020.3020900

Abstract: In this article, we report the development of a novel physics-based analytical model for explaining the current–voltage relationship in Schottky barrier (SB) 2D material field effect transistors (FETs). The model has at its core the calculation of the surface-potential (SP) which is accomplished by invoking 2-D density of states in conjunction with Fermi–Dirac (FD) distribution for electron and hole statistics. The explicit computation for the SP, carried out using the Lambert-W function together with Halley’s method, is used to construct the SP-based band-diagram for realizing the transparency of the SBs. Thereafter, the ambipolar current is derived in terms of the electron and hole injection phenomena the thermionic emission and Fowler–Nordheim tunneling mechanisms at the SB contacts. Furthermore, drift-diffusion current is derived in terms of the SP and incorporated in the model to account for the scattering in the intrinsic 2D channel. Finally, the Verilog-A model is validated against experimental IV data reported in the literature for two different 2D material systems. This is the first demonstration of an explicit SP-based SPICE model for ambipolar SB-2-D-FETs that is simultaneously built on tunneling-emission and driftdiffusion formalisms.

Fig: (a) Band-diagram sketched along positive y-direction underneath the source electrode. Blue and black lines represent bands before and after applying Vgs. (b) ψ-based diagram sketched along positive x, constructed after calculating ψs and ψd. The geometrical screening length λ is given by λ ≈ (tox t2D)^1/2.

Acknowledgement: This work was supported in part by the National Project Implementation Unit (NPIU) through the third phase of Technical Education Quality Improvement Programme (TEQIP-III) Project and in part by DST-SERB Startup Research Grant under Award SRG/2019/001122.

[paper] First Principles Based Compact Model for 2D-Channel MOSFETs

Das, Biswapriyo, and Santanu Mahapatra

First Principles Based Compact Model for 2D-Channel MOSFETs

researchgate.net online publication

Abstract: We propose a generalized compact model for any two-dimensional material channel-based metal-oxide-semiconductor field-effect transistors. Unlike existing ones, the proposed model is first principles based and thus has ability to predict the circuit performance only using the crystallographic information of the channel material. It is ‘core’ in nature and developed following the industry-standard drift-diffusion formalism based ‘top-down’ hierarchy employing the FermiDirac statistics. We also implement the model in professional circuit simulator and good convergence is observed in 15-stage ring oscillator simulation.

Fig: Synopsis of the modeling framework. First, certain material specific parameters are extracted employing density functional theory computations and Hamiltonian calibration, which thereafter are used to develop the compact device model of the 2D-channel MOSFET using drift-diffusion formalism. The drain current and terminal charges obtained henceforth are used to implement digital circuits in commercial circuit simulator using its Verilog-AMS interface. 

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