Electrical and Computer Engineering Commons^™

Experimental And Design Effort To Understand A Wider Sense Of Memory Application, Nicholas Zogbi

Discovery Undergraduate Interdisciplinary Research Internship

Magnetic Random-Access Memory (mRAM) is a more efficient, smaller, and less power-hungry memory device that can be implemented into computers. Using Magnetic Tunnel Junctions (MTJ) we store memory in devices that are far less complex than other types of memory with just the use of currents and magnetic fields changing the data.

In collaboration with the System-on-Chip Extension Technologies (SoCET) and Computing Advances by Probabilistic Spin Logic (CAPSL) groups, we have been working on using the characteristics of MTJs to characterize available commercial mRAM devices so we can have a better understanding of the thresholds of the MTJs. The SoCET …

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 η_T~ 25%. …

Low Rank Approximation Method For Efficient Green's Function Calculation Of Dissipative Quantum Transport, Lang Zeng, Yu He, Michael Povolotskyi, Xiao Yan Liu, Gerhard Klimeck, Tillmann Kubis

Birck and NCN Publications

In this work, the low rank approximation concept is extended to the non-equilibrium Green’s function (NEGF) method to achieve a very efficient approximated algorithm for coherent and incoherent electron transport. This new method is applied to inelastic transport in various semiconductor nanodevices. Detailed benchmarks with exact NEGF solutions show (1) a very good agreement between approximated and exact NEGF results, (2) a significant reduction of the required memory, and (3) a large reduction of the computational time (a factor of speed up as high as 150 times is observed). A non-recursive solution of the inelastic NEGF transport equations of a …

General Transformations For Gpu Execution Of Tree Traversals, Michael Goldfarb, Youngjoon Jo, Milind Kulkarni

Department of Electrical and Computer Engineering Technical Reports

With the advent of programmer-friendly GPU computing environments, there has been much interest in offloading workloads that can exploit the high degree of parallelism available on modern GPUs. Exploiting this parallelism and optimizing for the GPU memory hierarchy is well-understood for regular applications that operate on dense data structures such as arrays and matrices. However, there has been significantly less work in the area of irregular algorithms and even less so when pointer-based dynamic data structures are involved. Recently, irregular algorithms such as Barnes-Hut and kd-tree traversals have been implemented on GPUs, yielding significant performance gains over CPU implementations. However, …

Optical Tcad On The Net: A Tight-Binding Study Of Inter-Band Light Transitions In Self-Assembled Inas/Gaas Quantum Dot Photodetectors, Hoon Ryu, Dukyun Nam, Bu-Young Ahn, Jongsuk Ruth Lee, Kumwon Cho, Sunhee Lee, Gerhard Klimeck, Mincheol Sin

Other Nanotechnology Publications

A new capability of our well-known NEMO 3-D simulator (Ref. Klimeck et al., 2007 [10]) is introduced by carefully investigating the utility of III–V semiconductor quantum dots as infrared photodetectors at a wavelength of 1.2–1.5 μm. We not only present a detailed description of the simulation methodology coupled to the atomistic sp3d5s∗ tight-binding band model, but also validate the suggested methodology with a focus on a proof of principle on small GaAs quantum dots (QDs). Then, we move the simulation scope to optical properties of realistically sized dome-shaped InAs/GaAs QDs that are grown by self- assembly and typically contain a …

Characterization Of Parallel Application Runtime Sensitivity On Multi-Core High Performance Computing Systems, Padma Priya Veeraraghavan

Purdue Polytechnic Masters Theses

A commonly seen behavior of parallel applications is that their runtime is influenced by network communication load. The way a parallel application is run in a network and the presence of other applications and processes in the network can contribute to a wide range of variations in the runtime. Therefore, in order to achieve consistent and optimal runtimes, it is important to understand and characterize the runtime sensitivity of parallel applications with respect to execution under the presence of network communication load.

In this research, runtime sensitivities for various parallel applications were studied by applying additional network communication load. In …