
A MultiScale Modeling Approach to Study Transport in Silicon Heterojunction Solar Cells
03 Nov 2015  Online Presentations  Contributor(s): Pradyumna Muralidharan, Dragica Vasileska, Stephen M. Goodnick, Stuart Bowden
IWCE 2015 presentation.

Application of the nanoHUB tools in the Classroom
28 Jul 2011  Online Presentations  Contributor(s): Dragica Vasileska
This online presentation describes the application of the nanoHUB tools in the classroom.

Research Within Vasileska Group
29 Jun 2010  Online Presentations  Contributor(s): Dragica Vasileska
This presentation outlines recent progress in reseach within Vasileska group in the area of random telegraph noise and thermal modeling, and modeling of GaN HEMTs.

Nanoelectronic Modeling Lecture 14: Open 1D Systems  Formation of Bandstructure
27 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck, Dragica Vasileska
The infinite periodic structure Kroenig Penney model is often used to introduce students to the concept of bandstructure formation. It is analytically solvable for linear potentials and shows critical elements of bandstructure formation such as core bands and different effective masses in different bands.

Nanoelectronic Modeling Lecture 12: Open 1D Systems  Transmission through Double Barrier Structures  Resonant Tunneling
27 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck, Dragica Vasileska
This presentation shows that double barrier structures can show unity transmission for energies BELOW the barrier height, resulting in resonant tunneling. The resonance can be associated with a quasi bound state, and the bound state can be related to a simple particle in a box calculation.

Nanoelectronic Modeling Lecture 09: Open 1D Systems  Reflection at and Transmission over 1 Step
25 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck, Dragica Vasileska, Samarth Agarwal
One of the most elemental quantum mechanical transport problems is the solution of the time independent Schrödinger equation in a onedimensional system where one of the two half spaces has a higher potential energy than the other. The analytical solution is readily obtained using a scattering matrix approach where wavefunction amplitude and slope are matched at the interface between the two halfspaces. Of particular interest are the wave/particle injection from the lower potential energy halfspace.

Nanoelectronic Modeling Lecture 02: (NEMO) Motivation and Background
25 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck, Dragica Vasileska
Fundamental device modeling on the nanometer scale must include effect of open systems, high bias, and an atomistic basis. The nonequilibrium Green Function Formalism (NEGF) can include all these components in a fundamentally sound approach and has been the basis for a few novel device simulation tools.

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.

Nanoelectronic Modeling Lecture 10: Open 1D Systems  Transmission through & over 1 Barrier
31 Dec 2009  Online Presentations  Contributor(s): Gerhard Klimeck, Dragica Vasileska, Samarth Agarwal
Tunneling and interference are critical in the understanding of quantum mechanical systems. The 1D time independent Schrödinger equation can be easily solved analytically in a scattering matrix approach for a system of a single potential barrier. The solution is obtained by matching wavefunction values and derivatives at the two interfaces in the spatial domain. This simple example shows the extended nature of wavefunctions, the nonlocal effects of local potential variations, the formation of resonant states through interference, and quantum mechanical tunneling in its simplest form.

Quantum and Thermal Effects in Nanoscale Devices
18 Sep 2008  Online Presentations  Contributor(s): Dragica Vasileska
To investigate lattice heating within a Monte Carlo device simulation framework, we simultaneously solve the Boltzmann transport equation for the electrons, the 2D Poisson equation to get the selfconsistent fields and the hydrodynamic equations for acoustic and optical phonons. The phonon temperature then determines the choice of the scattering table. The bottom of the buried oxide layer (BOX) is assumed to be isothermal boundary and the temperature at that boundary is set to 300K. Another isothermal contact is the gate and the gate temperature is varied between 300600 K. It is important to note that it takes only 45 Gummel cycles to get convergence in the current up to the third digit. More details of the simulation procedure can be found in Ref. [2 ]. We find that in dual gate devices there exists larger bottleneck between acoustic and optical phonons which causes about 4% more degradation in the current in this device structure when compared to the single gate structure. This is easily explainable with the fact that there are more carriers in the DG structure and the optical to acoustic phonon decay is not fast enough so that heating has more influence on the carrier drift velocity and, therefore, onstate current in dualgate devices. In fact, we do observe degradation in the average carrier velocity in the dualgate devices when compared to single FD SOI device structure. Note that the dualgate structure is a structure of choice according to these investigations because even though there is 4% more current degradation, the magnitude of the oncurrent is 1.51.8 times larger. Thus, we can trade off slight increase in current degradation due to lattice heating for more current drive.

Is dual gate device structure better from a thermal perspective?
01 Sep 2008  Online Presentations  Contributor(s): Dragica Vasileska, Stephen M. Goodnick
This presentation illustrates several points. First, it is shown that in nanoscale devices there is less degradation due to heating effects due to nonstationary nature of the carrier transport (velocity overshoot) in the device, which, in turn, makes less probable the interaction with phonons. Second, it is shown that degradation can further be reduced if using Silicon on Diamond devices. Third, it is quantitatively demonstrated that dual gate devices are better from a thermal perspective ...

Nanotechnology: Yesterday, Today and Tomorrow
01 Sep 2008  Online Presentations  Contributor(s): Dragica Vasileska
This presentation illustrates the development of nanotechnology from the birth of the transistor up to today and it also speculates what is going to happen in the future.

BJT Operation Description
18 Jul 2008  Online Presentations  Contributor(s): Dragica Vasileska
This set of powerpoint slides is ment for undergraduate and first year graduate students and describe the basic principles of operation of Bipolar Junction Transistor.www.eas.asu.edu/~vasileskNSF Career

MOSFET Operation Description
18 Jul 2008  Online Presentations  Contributor(s): Dragica Vasileska
This set of slides gives the students basic understanding of MOSFET operation description.www.eas.asu.edu/~vasileskNSF Career

MOS Capacitors: Theory and Modeling
18 Jul 2008  Online Presentations  Contributor(s): Dragica Vasileska
These slides can help users acquire a basic understanding of MetalOxideSemiconductor (MOS) capacitors.

Why QuaMC 2D and ParticleBased Device Simulators?
02 May 2008  Online Presentations  Contributor(s): Dragica Vasileska, Shaikh S. Ahmed, Gerhard Klimeck
We describe the need for particlebased device simulators when modeling nanoscale devices.

Examples for QuaMC 2D particlebased device Simulator Tool
10 May 2008  Online Presentations  Contributor(s): Dragica Vasileska, Shaikh S. Ahmed, Gerhard Klimeck
We provide three examples that demonstrate the full capabilities of QuaMC 2D for alternative device technologies.

Modeling Coulomb Effects in Nanoscale Devices
26 Apr 2008  Online Presentations  Contributor(s): Dragica Vasileska, Shaikh S. Ahmed, David K. Ferry
We describe the development of the modeling efforts focused towards proper description of the threshold voltage fluctuations due to the discrete impurity effects (different number and different distribution of the impurities from device to device on the same chip).NSF, ONRW. J. Gross, D. Vasileska and D. K. Ferry, "A Novel Approach for Introducing the ElectronElectron and ElectronImpurity Interactions in ParticleBased Simulations," IEEE Electron Device Lett. 20, No. 9, pp.463465 ...

Ensemble Monte Carlo Method Described
27 Apr 2008  Online Presentations  Contributor(s): Dragica Vasileska, Gerhard Klimeck, Mark Lundstrom, David K. Ferry
In this presentation we give an overview of the implementation details of the Ensemble Monte Carlo method for mobility and drift velocity calculation in arbitrary materials and arbitrary crystalographic orientations.NSFCareer, ONR

ParticleBased Device Simulators Description
28 Apr 2008  Online Presentations  Contributor(s): Dragica Vasileska, Shaikh S. Ahmed, Gerhard Klimeck
In this presentation we give an overview of partclebased device simulations with focus on implementation details.

What is CMOS Technology Facing?
07 Jul 2006  Online Presentations  Contributor(s): Dragica Vasileska
Introduction of QuantumMechanical Effects in Device Simulation

MOS Capacitors: Description and Semiclassical Simulation With PADRE
26 Jun 2006  Online Presentations  Contributor(s): Dragica Vasileska
Introduction of QuantumMechanical Effects in Device Simulation

Introduction to Silvaco Simulation Software
02 Jun 2006  Online Presentations  Contributor(s): Dragica Vasileska
Silvaco/PADRE Description and Application to Device Simulation

Introduction to DD Modeling with PADRE
02 Jun 2006  Online Presentations  Contributor(s): Dragica Vasileska
Silvaco/PADRE Description and Application to Device Simulation

DriftDiffusion Model, Mobility Modeling
02 Jun 2006  Online Presentations  Contributor(s): Dragica Vasileska
DriftDiffusion Model