Publications

Gao, Xujiao G.; Mamaluy, Denis M.; Tracy, Lisa A.; Ward, Daniel R.; Bussmann, Ezra B.

Abstract not provided.

Mamaluy, Denis M.; Mendez Granado, Juan P.; Gao, Xujiao G.

Abstract not provided.

Mamaluy, Denis M.; Gao, Xujiao G.; Maurer, Leon M.

Abstract not provided.

Huang, Andy H.; Gao, Xujiao G.; Pawlowski, Roger P.; Gates, Jason M.; Musson, Lawrence M.; Hennigan, Gary L.; Negoita, Mihai N.

Abstract not provided.

Huang, Andy H.; Gao, Xujiao G.; Pawlowski, Roger P.; Gates, Jason M.; Musson, Lawrence M.; Hennigan, Gary L.; Negoita, Mihai N.

Abstract not provided.

Baczewski, Andrew D.; Gao, Xujiao G.; Jacobson, Noah T.; Nielsen, Erik N.; Salinger, Andrew G.; Muller, Richard P.; Gamble, John K.

Abstract not provided.

Huang, Andy H.; Gao, Xujiao G.; Pawlowski, Roger P.; Gates, Jason M.; Musson, Lawrence M.; Hennigan, Gary L.; Negoita, Mihai N.

Abstract not provided.

Peterson, Kara J.; Bochev, Pavel B.; Perego, Mauro P.; Gao, Xujiao G.

Abstract not provided.

Peterson, Kara J.; Bochev, Pavel B.; Perego, Mauro P.; Gao, Xujiao G.

Abstract not provided.

Musson, Lawrence M.; Hennigan, Gary L.; Gao, Xujiao G.; Mamaluy, Denis M.

Abstract not provided.

Mamaluy, Denis M.; Gao, Xujiao G.; Tierney, Brian D.

Transition metal oxide (TMO) memristors have recently attracted special attention from the semiconductor industry and academia. Memristors are one of the strongest candidates to replace flash memory, and possibly DRAM and SRAM in the near future. Moreover, memristors have a high potential to enable beyond-CMOS technology advances in novel architectures for high performance computing (HPC). The utility of memristors has been demonstrated in reprogrammable logic (cross-bar switches), brain-inspired computing and in non-CMOS complementary logic. Indeed, the potential use of memristors as logic devices is especially important considering the inevitable end of CMOS technology scaling that is anticipated by 2025. In order to aid the on-going Sandia memristor fabrication effort with a memristor design tool and establish a clear physical picture of resistance switching in TMO memristors, we have created and validated with experimental data a simulation tool we name the Memristor Charge Transport (MCT) Simulator.

Journal of Physics. D, Applied Physics

Hughart, David R.; Gao, Xujiao G.; Mamaluy, Denis M.; Marinella, Matthew J.; Mickel, Patrick R.

We present a study of the 'snap-back' regime of resistive switching hysteresis in bipolar TaO_x memristors, identifying power signatures in the electronic transport. Using a simple model based on the thermal and electric field acceleration of ionic mobilities, we provide evidence that the 'snap-back' transition represents a crossover from a coupled thermal and electric-field regime to a primarily thermal regime, and is dictated by the reconnection of a ruptured conducting filament. We discuss how these power signatures can be used to limit filament radius growth, which is important for operational properties such as power, speed, and retention.

Mamaluy, Denis M.; Gao, Xujiao G.; Marinella, Matthew J.

Abstract not provided.

ECS Transactions

Gao, Xujiao G.; Mamaluy, Denis M.; Cyr, E.C.; Marinella, M.J.

As CMOS technology approaches the end of its scaling, oxide-based memristors have become one of the leading candidates for post-CMOS memory and logic devices. To facilitate the understanding of physical switching mechanisms and accelerate experimental development of memristors, we have developed a three-dimensional fully-coupled electrical and thermal transport model, which captures all the important processes that drive memristive switching and is applicable for simulating a wide range of memristors. The model is applied to simulate the RESET and SET switching in a 3D filamentary TaOx memristor. Extensive simulations show that the switching dynamics of the bipolar device is determined by thermally-activated field-dominant processes: with Joule heating, the raised temperature enables the movement of oxygen vacancies, and the field drift dominates the overall motion of vacancies. Simulated current-voltage hysteresis and device resistance profiles as a function of time and voltage during RESET and SET switching show good agreement with experimental measurement.

Gao, Xujiao G.; Huang, Andy H.; Peterson, Kara J.; Hennigan, Gary L.; Musson, Lawrence M.; Bochev, Pavel B.

Abstract not provided.

ECS Transactions (Online)

Gao, Xujiao G.; Mamaluy, Denis M.; Mickel, Patrick R.; Marinella, Matthew J.

In this paper, we present a fully-coupled electrical and thermal transport model for oxide memristors that solves simultaneously the time-dependent continuity equations for all relevant carriers, together with the time-dependent heat equation including Joule heating sources. The model captures all the important processes that drive memristive switching and is applicable to simulate switching behavior in a wide range of oxide memristors. The model is applied to simulate the ON switching in a 3D filamentary TaOx memristor. Simulation results show that, for uniform vacancy density in the OFF state, vacancies fill in the conduction filament till saturation, and then fill out a gap formed in the Ta electrode during ON switching; furthermore, ON-switching time strongly depends on applied voltage and the ON-to-OFF current ratio is sensitive to the filament vacancy density in the OFF state.

Muller, Richard P.; Baczewski, Andrew D.; Blume-Kohout, Robin J.; Carroll, Malcolm; Gamble, John K.; Gao, Xujiao G.; Jacobson, Noah T.; Montano, Ines M.; Nielsen, Erik N.; Rudinger, Kenneth M.; Witzel, Wayne W.

Abstract not provided.

Applied Physics Letters

Mamaluy, Denis M.; Gao, Xujiao G.

We predict that within next 15 years a fundamental down-scaling limit for CMOS technology and other Field-Effect Transistors (FETs) will be reached. Specifically, we show that at room temperatures all FETs, irrespective of their channel material, will start experiencing unacceptable level of thermally induced errors around 5-nm gate lengths. These findings were confirmed by performing quantum mechanical transport simulations for a variety of 6-, 5-, and 4-nm gate length Si devices, optimized to satisfy high-performance logic specifications by ITRS. Different channel materials and wafer/channel orientations have also been studied; it is found that altering channel-source-drain materials achieves only insignificant increase in switching energy, which overall cannot sufficiently delay the approaching downscaling limit. Alternative possibilities are discussed to continue the increase of logic element densities for room temperature operation below the said limit.

Baczewski, Andrew D.; Frees, Adam F.; Gamble, John K.; Gao, Xujiao G.; Jacobson, Noah T.; Mitchell, John A.; Montano, Ines M.; Muller, Richard P.; Nielsen, Erik N.

Abstract not provided.

Gao, Xujiao G.; Mamaluy, Denis M.; Mickel, Patrick R.; Marinella, Matthew J.

Abstract not provided.

ECS Transactions

Gao, Xujiao G.; Mamaluy, Denis M.; Mickel, P.R.; Marinella, M.

We present a fully-coupled electrical and thermal transport model for oxide memristors that solves simultaneously the time-dependent continuity equations for all relevant carriers, together with the time-dependent heat equation including Joule heating sources. The model captures all the important processes that drive memristive switching, and is applicable to simulate switching behavior in a wide range of oxide memristors. The model is applied to simulate the ON switching in a 3D filamentary TaOx memristor. Simulation results show that, for uniform vacancy density in the OFF state, vacancies fill in the conduction filament till saturation, and then fill out a gap formed in the Ta electrode during ON switching; furthermore, ON-switching time strongly depends on applied voltage and the ON-to-OFF current ratio is sensitive to the filament vacancy density in the OFF state.

Muller, Richard P.; Aidun, John B.; Baczewski, Andrew D.; Gao, Xujiao G.; Metodi, Tzvetan S.; Mitchell, John A.; Sterk, Jonathan D.; Gamble, John K.; Blume-Kohout, Robin J.; Jacobson, Noah T.

Abstract not provided.

Peterson, Kara J.; Bochev, Pavel B.; Perego, Mauro P.; Gao, Xujiao G.

Abstract not provided.

Mamaluy, Denis M.; Gao, Xujiao G.; Tierney, Brian D.

We created a highly efficient, universal 3D quant um transport simulator. We demonstrated that the simulator scales linearly - both with the problem size (N) and number of CPUs, which presents an important break-through in the field of computational nanoelectronics. It allowed us, for the first time, to accurately simulate and optim ize a large number of realistic nanodevices in a much shorter time, when compared to other methods/codes such as RGF[%7EN 2.333 ]/KNIT, KWANT, and QTBM[%7EN 3 ]/NEMO5. In order to determine the best-in-class for different beyond-CMOS paradigms, we performed rigorous device optimization for high-performance logic devices at 6-, 5- and 4-nm gate lengths. We have discovered that there exists a fundamental down-scaling limit for CMOS technology and other Field-Effect Transistors (FETs). We have found that, at room temperatures, all FETs, irre spective of their channel material, will start experiencing unacceptable level of thermally induced errors around 5-nm gate lengths.

Muller, Richard P.; Nielsen, Erik N.; Gao, Xujiao G.; Salinger, Andrew G.; Kalashnikova, Irina; Carroll, Malcolm

Abstract not provided.