NEMO 1-D: the first NEGF-based TCAD tool

Abstract

The fundamentally sound non-Equilibrium Green's function (NEGF) approach provides the theoretical basis for NEMO 1-D as the first nanoelectronic TCAD tool. Effects of quantum charging, bandstructure and incoherent scattering from alloy disorder, interface roughness, acoustic phonons, and polar optical phonons are modeled. Engineers and experimentalists who desire a black-box design tool as well as theorists who are interested in a detailed investigation of the physics have found NEMO useful. Access to this comprehensive theoretical framework is accommodated by a graphical user interface (GUI) which configures the usage of a collection of models that trade off physical content with speed and memory requirements. This article describes the NEMO origin, provides modern references to NEGF, accumulates the diverse references to the NEMO results, and provides a perspective on NEGF in future TCAD tools. History and AcknowledgementsThe nanoelectronic modeling (NEMO) program is the result of a multi-year development effort involving an industrial research laboratory (Central Research Laboratory of Texas Instruments, later transferred to Raytheon TI Systems), several Universities (UT Dallas, Ohio State U., U. Alabama in Huntsville), and a US Federally Funded Development and Research Center (NASA, JPL, California Institute of Technology). The original development began in 1993 with the lead of TI and concluded with the delivery of the tool to the US government sponsor in January of 1998. The development then shifted to the NASA Jet Propulsion Laboratory. A large number of people involved with the NEMO 1-D code over the past 11 years. I would especially like to acknowledge the key contributors to the development of the tool: Drs. Roger Lake, R. Chris Bowen, Dan Blanks, Bill Frensley, and Tim Boykin. The primary application focus was the quantitative modeling of resonant tunneling diodes (RTDs). These III-V high speed devices were developed for high speed applications such as analog-digital-converters [1] and memory devices [2]. Modern NEGF Method References for Carrier TransportNovel aspects of the theory developed under the NEMO program are described in detail in [3]. Early work on the NEGF approach has been focussed on bulk many-body interactions and the literature was difficult to penetrate. Just over the past few years Datta has published [4,5] introductions to NEGF that enable the electrical engineer to

Introducing Open Boundary Conditions in Modeling Nonperiodic Materials and Interfaces: The Impact of the Periodicity Assumption

“…Therefore, all retarded Green’s functions are solved recursively , to limit the required peak memory and to allow for explicit consideration of up to 3 million atoms in this work. Many publications − and online lectures , on recursive Green’s functions describe the method in high detail. Details of the CAP method are discussed in refs and .…”