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Nanoelectronic Modeling Lecture 22: NEMO1D - Motivation, History and Key Insights

By Gerhard Klimeck

Purdue University

Published on


The primary objective of the NEMO-1D tool was the quantitative modeling of high performance Resonant Tunneling Diodes (RTDs). The software tool was intended for Engineers (concepts, fast turn-around, interactive) and Scientists (detailed device anaysis). Therefore various degrees of sohphistication have been built into the tool which allow the users to trade off accuracy and completeness of the models against computation time and memory usage.

The Nanoelectronic Modeling tool (NEMO) is a 1-D device design tool for the quantum mechanical simulation of electron (and hole) states in semiconductor heterostructures. A variety of material systems such as GaAs, InP and Si can presently be analysed. A graphical user interface enables the simple enrty of the heterostructure, the entry of the simulation parameters, the simulation control, and the analysis of the data. The code consists presently of approximately 255,000 lines of code written in C, FORTRAN, F90 and yacc.

The four key modeling aspects that resulted in the accurate modeling of RTDs are:

  • Proper treatment of extended contacts. Contacts typically contain resonance states which modify the injection of carriers into the central RTD structure.
  • Proper treatment of the quantum mechanical charging in the central RTD AND the contacts.
  • Proper treatment of the material bandstructure properties, such as non-parabolicity, band-warping, and Gamma-X transistions, and
  • at low temperatures the proper treatement of electron scattering due to optical phonons, acoustic phonons, and interface roughness...

NEMO was developed at the Applied Research Laboratory of Raytheon (formerly known as the Central Research Lab of Texas Instruments) with U.S. government funding. The tool was delivered to the U.S. government and it was available to the U.S. research community.

Learning Objectives:

    General NEMO 1D modeling challenge – understanding valley current. Overview of the state-of-the art knowledge of resonant tunneling diode simulation before the NEMO project in 1994 High level overview of alternative modeling methodologies available in 1994 Key simulation results for room temperature, high performance RTDs Software overview State-of-the-art knowledge in 1998 / 2000

Cite this work

Researchers should cite this work as follows:

  • Gerhard Klimeck (2010), "Nanoelectronic Modeling Lecture 22: NEMO1D - Motivation, History and Key Insights,"

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Università di Pisa, Pisa, Italy

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