
NEMO5 Tutorials (2012 Summer School)
19 Jul 2012  Courses  Contributor(s): James Fonseca, Tillmann Christoph Kubis, Michael Povolotskyi, Jean Michel D Sellier, Parijat Sengupta, Junzhe Geng, Mehdi Salmani Jelodar, Seung Hyun Park, Gerhard Klimeck

Analytical and Numerical Solution of the Double Barrier Problem
28 Jun 2010  Teaching Materials  Contributor(s): Gerhard Klimeck, Parijat Sengupta, Dragica Vasileska
Tunneling is fully quantummechanical effect that does not have classical analog. Tunneling has revolutionized surface science by its utilization in scanning tunneling microscopes. In some device applications tunneling is required for the operation of the device (Resonant tunneling diodes, EEPROMs – floating gate memories), but in some cases it leads to unwanted power dissipation, such as gate leakage in both MOS and Schottky transistors. Resonant tunneling diodes, due to the tunneling …

Nanoelectronic Modeling Lecture 11: Open 1D Systems  The Transfer Matrix Method
31 Dec 2009  Online Presentations  Contributor(s): Gerhard Klimeck, Dragica Vasileska, Samarth Agarwal, Parijat Sengupta
The transfer matrix approach is analytically exact, and “arbitrary” heterostructures can apparently be handled through the discretization of potential changes. The approach appears to be quite appealing. However, the approach is inherently unstable for realistically extended devices which exhibit electrostatic band bending or include a large number of basis sets.

Tutorial Introduction to Topological Insulators
08 May 2014  Online Presentations  Contributor(s): Parijat Sengupta
An important pursuit in semiconductor physics is to discover new materials to sustain the continuous progress and improvements in the current electronic devices.
Traditionally, three material types are in use: 1) Metals 2) Semiconductors 3) Insulators. All the three material types are classified according to the energy gap between conduction and valence bands derived from band theory of solids. Recent theoretical predictions and confirmed by experimental observations have provided evidence …

NEMO5 Tutorial 7: Using NEMO5 to Quantitatively Predict Topological Insulator Behaviour
18 Jul 2012  Online Presentations  Contributor(s): Parijat Sengupta

Band Structure Lab Exercise
28 Jun 2010  Teaching Materials  Contributor(s): Gerhard Klimeck, Parijat Sengupta, Dragica Vasileska
Investigations of the electron energy spectra of solids form one of the most active fields of research. Knowledge of band theory is essential for application to specific problems such as Gunn diodes, tunnel diodes, photodetectors etc. There are several standard methods to compute the band structure of solids and confined devices (such as wells, wires, and dots) carved out of them. We will use the Band structure lab to generate the band diagrams of several materials and devices. A full list of …

Crystal Viewer Lab Exercise
28 Jun 2010  Teaching Materials  Contributor(s): Gerhard Klimeck, Parijat Sengupta, Dragica Vasileska
A central problem in the investigation of material properties involves the examination of the underlying blocks that aggregate to form macroscopic bodies. These underlying blocs own a definite arrangement that is repeated in three dimensions to give the crystal structure. We will try to explore the geometry of some well known class of materials (e.g., diamond, zincblende, wurtzite etc,) and learn techniques of identifying planes (Miller indices) and directions in these crystal structures. …

Quantum Bound States Exercise
16 Jun 2010  Teaching Materials  Contributor(s): Gerhard Klimeck, Parijat Sengupta, Dragica Vasileska
Exercise Background
Quantummechanical systems (structures, devices) can be separated into open systems and closed systems. Open systems are characterized with propagating or current carrying states. Closed (or bound) systems are described with localized wavefunctions. One such system is a triangular potential well in MOS capacitors; another one is rectangular quantum well in heterostructure devices. In addition to this, every observable in Quantum Mechanics (like position, momentum, energy) …

Periodic Potentials Exercise
16 Jun 2010  Teaching Materials  Contributor(s): Gerhard Klimeck, Parijat Sengupta, Dragica Vasileska
In this exercise, various calculations of the electronic band structure of a onedimensional crystal are performed with the KronigPenney (KP) model. This model has an analytical solution and therefore allows for simple calculations. More realistic models always require extensive numeric calculations, often on the fastest computers available. The electronic band structure is directly related to many macroscopic properties of the material and therefore of large interest. Nowadays, hypothetical …

Quantum Tunneling Exercise
16 Jun 2010  Teaching Materials  Contributor(s): Gerhard Klimeck, Parijat Sengupta, Dragica Vasileska
Exercise Background
Tunneling is fully quantummechanical effect that does not have classical analog. Tunneling has revolutionized surface science by its utilization in scanning tunneling microscopes. In some device applications tunneling is required for the operation of the device (Resonant tunneling diodes, EEPROMs â�� floating gate memories), but in some cases it leads to unwanted power dissipation, such as gate leakage in both MOS and Schottky transistors.
Exercise Objectives
The …

Negative Differential Resistivity Exercise
28 Jun 2010  Teaching Materials  Contributor(s): Gerhard Klimeck, Parijat Sengupta, Dragica Vasileska
In certain semiconductors such as GaAs and InP the average velocity as a function of field strength displays a maximum followed by a regime of decreasing velocity. Hilsum, Ridley, and Watkins postulated that peculiarities in the band structure of semiconductors would lead to the above phenomenon. The conduction band in compound semiconductors such as GaAs has away from the Г point (centre of Brillouin zone) local minima at the X and L valleys (satellite valleys). These valleys are a few …