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Full-Text Articles in Engineering
Bifacial Si Heterojunction-Perovskite Organic-Inorganic Tandem To Produce Highly Efficient (Η T * ~ 33%) Solar Cell, Reza Asadpour, Raghu Vamsi Krishna Chavali, Mohammad Ryyan Khan, Muhammad Ashraful Alam
Bifacial Si Heterojunction-Perovskite Organic-Inorganic Tandem To Produce Highly Efficient (Η T * ~ 33%) Solar Cell, Reza Asadpour, Raghu Vamsi Krishna Chavali, Mohammad Ryyan Khan, Muhammad Ashraful Alam
Department of Electrical and Computer Engineering Faculty Publications
As single junction photovoltaic (PV) technologies both Si heterojunction (HIT) and perovskite based solar cells promise high efficiencies at low cost. Intuitively a traditional tandem cell design with these cells connected in series is expected to improve the efficiency further. Using a self-consistent numerical modeling of optical and transport characteristics however we find that a traditional series connected tandem design suffers from low JSC due to band-gap mismatch and current matching constraints. Specifically a traditional tandem cell with state-of-the-art HIT ( η=24% ) and perovskite ( η=20% ) sub-cells provides only a modest tandem efficiency of ηT~ 25%. …
A Simple Boltzmann Transport Equation For Ballistic To Diffusive Transient Heat Transport, Mark S. Lundstrom, Jesse Maassen
A Simple Boltzmann Transport Equation For Ballistic To Diffusive Transient Heat Transport, Mark S. Lundstrom, Jesse Maassen
Department of Electrical and Computer Engineering Faculty Publications
Developing simplified, but accurate, theoretical approaches to treat heat transport on all length and time scales is needed to further enable scientific insight and technology innovation. Using a simplified form of the Boltzmann transport equation (BTE), originally developed for electron transport, we demonstrate how ballistic phonon effects and finite-velocity propagation are easily and naturally captured. We show how this approach compares well to the phonon BTE, and readily handles a full phonon dispersion and energy-dependent mean-free-path. This study of transient heat transport shows (i) how fundamental temperature jumps at the contacts depend simply on the ballistic thermal resistance, (ii) that …
Computational Electronics For The 21st Century: Reflections On The Past, Present, And Future, Mark S. Lundstrom
Computational Electronics For The 21st Century: Reflections On The Past, Present, And Future, Mark S. Lundstrom
Department of Electrical and Computer Engineering Faculty Publications
The author’s career has coincided with the development of numerical simulation into an essential component of semiconductor device technology research and development. We now have a sophisticated suite of simulation capabilities along with new challenges for 21st Century electronics. This talk presents a short history of the field and a description of the current state of the art, but it concentrates on lessons learned and thoughts about how computational electronics can continue to contribute effectively to the development of new electronic device technologies. The author will argue that electronics is changing, and that computational electronics can play a key role …
Steady-State Heat Transport: Ballistic-To-Diffusive With Fourier's Law, Jesse Maassen, Mark S. Lundstrom
Steady-State Heat Transport: Ballistic-To-Diffusive With Fourier's Law, Jesse Maassen, Mark S. Lundstrom
Department of Electrical and Computer Engineering Faculty Publications
It is generally understood that Fourier's law does not describe ballistic phonon transport, which is important when the length of a material is similar to the phonon mean-free-path. Using an approach adapted from electron transport, we demonstrate that Fourier's law and the heat equation do capture ballistic effects, including temperature jumps at ideal contacts, and are thus applicable on all length scales. Local thermal equilibrium is not assumed, because allowing the phonon distribution to be out-of-equilibrium is important for ballistic and quasi-ballistic transport. The key to including the non-equilibrium nature of the phonon population is to apply the proper boundary …
Photovoltaic Material Characterization With Steady-State And Transient Photoluminescence, Xufeng Wang, Jayprakash Bhosale, James Moore, Rehan Kapadia, Peter Bermel, Ali Javey, Mark S. Lundstrom
Photovoltaic Material Characterization With Steady-State And Transient Photoluminescence, Xufeng Wang, Jayprakash Bhosale, James Moore, Rehan Kapadia, Peter Bermel, Ali Javey, Mark S. Lundstrom
Department of Electrical and Computer Engineering Faculty Publications
In this study, we develop an approach to characterize the surface and bulk properties for thin films of photovoltaic materials by combining two experimental photoluminescence (PL) techniques with one multiphysics simulation. This contactless, in-line characterization technique allows reliable extraction of key lifetime parameters. In this study, we first discuss the strengths and weaknesses of both steady-state and transient PL techniques (specifically, steady-state PL excitation spectroscopy and time-resolved PL) and show that combining them with numerical simulation can be used to extract surface and bulk lifetimes self consistently. The method is applied to InP thin films grown with a novel vapor-liquid-solid …
Emission-Diffusion Theory Of The Mosfet, Mark S. Lundstrom, Supriyo Datta, Xingshu Sun
Emission-Diffusion Theory Of The Mosfet, Mark S. Lundstrom, Supriyo Datta, Xingshu Sun
Department of Electrical and Computer Engineering Faculty Publications
An emission-diffusion theory that describes MOSFETS from the ballistic to diffusive limits is developed. The approach extends the Crowell-Sze treatment of metalsemiconductor junctions to MOSFETs and is equivalent to the scattering/transmission model of the MOSFET. The paper demonstrates that the results of the transmission model can be obtained from a traditional, drift-diffusion analysis when the boundary conditions are properly specified, which suggests that traditional drift-diffusion MOSFET models can also be extended to comprehend ballistic limits.
Mass Media And The Contagion Of Fear: The Case Of Ebola In America, Sherry M J Towers, Shehzad Afzal, Gilbert Bernal, Nadya T. Bliss, Baltazar Espinoza, Jasmine Jackson, Julia Judson-Garcia, Maryam Khan, Michael Lin, Robert Mamada, Victor M. Moreno, Fereshteh Nazari, Kamaldeen Okumeye, Mary L. Ross, Claudia Rodriguez, Jan Medlock, David S. Ebert, Carlos Castillo-Chavez,
Mass Media And The Contagion Of Fear: The Case Of Ebola In America, Sherry M J Towers, Shehzad Afzal, Gilbert Bernal, Nadya T. Bliss, Baltazar Espinoza, Jasmine Jackson, Julia Judson-Garcia, Maryam Khan, Michael Lin, Robert Mamada, Victor M. Moreno, Fereshteh Nazari, Kamaldeen Okumeye, Mary L. Ross, Claudia Rodriguez, Jan Medlock, David S. Ebert, Carlos Castillo-Chavez,
Department of Electrical and Computer Engineering Faculty Publications
Background: In the weeks following the first imported case of Ebola in the U. S. on September 29, 2014, coverage of the very limited outbreak dominated the news media, in a manner quite disproportionate to the actual threat to national public health; by the end of October, 2014, there were only four laboratory confirmed cases of Ebola in the entire nation. Public interest in these events was high, as reflected in the millions of Ebola-related Internet searches and tweets performed in the month following the first confirmed case. Use of trending Internet searches and tweets has been proposed in the …