NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
2-D Modeling of Nanoscale MOSFETs: Non-Equilibrium Green's Function ApproachWe have developed physical approximations and computer code capable of realistically simulating 2-D nanoscale transistors, using the non-equilibrium Green's function (NEGF) method. This is the most accurate full quantum model yet applied to 2-D device simulation. Open boundary conditions and oxide tunneling are treated on an equal footing. Electrons in the ellipsoids of the conduction band are treated within the anisotropic effective mass approximation. Electron-electron interaction is treated within Hartree approximation by solving NEGF and Poisson equations self-consistently. For the calculations presented here, parallelization is performed by distributing the solution of NEGF equations to various processors, energy wise. We present simulation of the "benchmark" MIT 25nm and 90nm MOSFETs and compare our results to those from the drift-diffusion simulator and the quantum-corrected results available. In the 25nm MOSFET, the channel length is less than ten times the electron wavelength, and the electron scattering time is comparable to its transit time. Our main results are: (1) Simulated drain subthreshold current characteristics are shown, where the potential profiles are calculated self-consistently by the corresponding simulation methods. The current predicted by our quantum simulation has smaller subthreshold slope of the Vg dependence which results in higher threshold voltage. (2) When gate oxide thickness is less than 2 nm, gate oxide leakage is a primary factor which determines off-current of a MOSFET (3) Using our 2-D NEGF simulator, we found several ways to drastically decrease oxide leakage current without compromising drive current. (4) Quantum mechanically calculated electron density is much smaller than the background doping density in the poly silicon gate region near oxide interface. This creates an additional effective gate voltage. Different ways to. include this effect approximately will be discussed.
Document ID
20020038536
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Svizhenko, Alexei
(NASA Ames Research Center Moffett Field, CA United States)
Anantram, M. P.
(Computer Sciences Corp. United States)
Govindan, T. R.
(NASA Ames Research Center Moffett Field, CA United States)
Biegel, Bryan
(Computer Sciences Corp. United States)
Date Acquired
August 20, 2013
Publication Date
January 1, 2001
Subject Category
Solid-State Physics
Meeting Information
Meeting: 12th International Conference on Nonequilibrium Carrier Dynamics in Semiconductors
Country: Unknown
Start Date: August 27, 2001
End Date: August 31, 2001
Funding Number(s)
CONTRACT_GRANT: NASA Order A-61812-D
CONTRACT_GRANT: DTT59-99-D-00437
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Available Downloads

There are no available downloads for this record.
No Preview Available