Atomistic Electronic Structure Calculations of Unstrained Alloyed Systems Consisting of a Million Atoms

14 Jan 2008 | Publications | Contributor(s): Gerhard Klimeck, Timothy Boykin

The broadening of the conduction and valence band edges due to compositional disorder in alloyed materials of finite extent is studied using an s p3 s ∗ tight binding model. Two sources of broadening due to configuration and concentration disorder are identified. The concentrational disorder …

Atomistic Simulation of Realistically Sized Nanodevices Using NEMO 3-D: Part I − Models and Benchmarks

14 Jan 2008 | Publications | Contributor(s): Gerhard Klimeck, Shaikh S. Ahmed, Neerav Kharche, Hansang Bae, Steven Clark, Benjamin P Haley, Maxim Naumov, Hoon Ryu, Faisal Saied, marta prada, Marek Korkusinski, Timothy Boykin

Device physics and material science meet at the atomic scale of novel nanostructured semiconductors, and the distinction between new device or new material is blurred. Not only the quantum-mechanical effects in the electronic states of the device but also the granular atomistic representation of …

Atomistic Simulation of Realistically Sized Nanodevices Using NEMO 3-D—Part II: Applications

14 Jan 2008 | Publications | Contributor(s): Gerhard Klimeck, Shaikh S. Ahmed, Neerav Kharche, Marek Korkusinski, Muhammad Usman, marta prada, Timothy Boykin

In part I, the development and deployment of a general nanoelectronic modeling tool (NEMO 3-D) has been discussed. Based on the atomistic valence-force field and the sp3d5s* nearest neighbor tight-binding models, NEMO 3-D enables the computation of strain and electronic structure in nanostructures …

Development of a Nanoelectronic 3-D (NEMO 3-D ) Simulator for Multimillion Atom Simulations and Its Application to Alloyed Quantum Dots

14 Jan 2008 | Publications | Contributor(s): Gerhard Klimeck, Timothy Boykin

Material layers with a thickness of a few nanometers are common-place in today’s semiconductor devices. Before long, device fabrication methods will reach a point at which the other two device dimensions are scaled down to few tens of nanometers. The total atom count in such deca-nano devices is …

Empirical Tight-binding Parameterization of SmSe in the sp3d5f7s* model

26 Mar 2013 | Downloads | Contributor(s): Zhengping Jiang, Marcelo Kuroda, Yaohua Tan, Dennis M. Newns, Michael Povolotskyi, Timothy Boykin, Tillmann Christoph Kubis, Gerhard Klimeck, Glenn J. Martyna

The Empirical Tight Binding(ETB) method is widely used in atomistic device simulations. The reliability of such simulations depends very strongly on the choice of basis sets and the ETB parameters. The Piezoelectronic Transistor (PET) has been proposed as a post-CMOS device for fast, low-power …

Nanoelectronic Modeling Lecture 33: Alloy Disorder in Bulk

07 Jul 2010 | Online Presentations | Contributor(s): Gerhard Klimeck, Timothy Boykin, Chris Bowen

This presentation discusses disorder in AlGaAs unstrained systems in bulk. Bandstructure of an ideal simple unit cell What happens when there is disorder? Concept of a supercell Band folding in a supercell Band extraction from the concept of approximate …

Nanoelectronic Modeling Lecture 34: Alloy Disorder in Quantum Dots

07 Jul 2010 | Online Presentations | Contributor(s): Gerhard Klimeck, Timothy Boykin, Chris Bowen

This presentation discusses the consequences of Alloy Disorder in strained InGaAs Quantum Dots Reminder of the origin of bandstructure and bandstructure engineering What happens when there is disorder? Concept of disorder in the local bandstructure Configuration noise, concentration …

Nanoelectronic Modeling Lecture 35: Alloy Disorder in Nanowires

07 Jul 2010 | Online Presentations | Contributor(s): Gerhard Klimeck, Timothy Boykin, Neerav Kharche, Mathieu Luisier, Neophytos Neophytou

This presentation discusses the consequences of Alloy Disorder in unstrained strained AlGaAs nanowires Relationship between dispersion relationship and transmission in perfectly ordered wires Band folding in Si nanowires Tranmisison in disordered wires – relationship to an approximate …

Tight Binding Parameters by DFT mapping

12 Sep 2012 | Notes | Contributor(s): Yaohua Tan, Michael Povolotskyi, Tillmann Christoph Kubis, Yu He, Zhengping Jiang, Gerhard Klimeck, Timothy Boykin

The Empirical Tight Binding(ETB) method is widely used in atomistic device simulations. The reliability of such simulations depends very strongly on the choice of basis sets and the ETB parameters. The traditional way of obtaining the ETB parameters is by fitting to experiment data,or critical …

Valley splitting in strained silicon quantum wells modeled with 2 degree miscuts, step disorder, and alloy disorder

14 Jan 2008 | Publications | Contributor(s): Neerav Kharche, marta prada, Timothy Boykin, Gerhard Klimeck

Valley splitting (VS) in strained SiGe/Si/SiGe quantum wells grown on (001) and 2° miscut substrates is computed in a magnetic field. Calculations of flat structures significantly overestimate, while calculations of perfectly ordered structures underestimate experimentally observed VS. Step …