Ultralow‐Power Atomic‐Scale Tin Transistor with Gate Potential in Millivolt

After decades of continuous scaling, further advancement of complementary metal-oxide-semiconductor (CMOS) technology across the entire spectrum of computing applications is today limited by power dissipation, which scales with the square of the supply voltage. Here, an atomic-scale tin transistor is demonstrated to perform conductive switching between bistable configurations with on/off potentials ≤2.5 mV in magnitude. In addition to the low operation voltage, the channel length of the transistor is determined experimentally and with density-functional theory to be ≤1 nm because the atoms instead of electrons are information carriers in this device. The conductance at on-states of the bistable configurations varies between 1.2 G$_{0}$ to 197 G$_{0}$ (G$_{0}$ = 2e$^{2}$ h$^{-1}$, e stands for the electron charge and h for Planck\u27s constant). Thus, the device can supply driving current from 1 to ≈375 µA in magnitude for logic circuits with the drain-source dc voltage at decades of millivolts. The switching frequency of the atomic-scale tin transistor has reached 2047 Hz. Furthermore, the on/off potentials in millivolts can reduce the energy consumption in the interconnects of integrated circuits at least by ≈400 times. Therefore, the atomic-scale tin transistor has prospects in digital circuits with ultralow-power dissipation and can contribute to the sustainability of modern society

Controlling Volatility and Nonvolatility of Memristive Devices by Sn Alloying

Memristive devices have attracted significant attention due to their downscaling potential, low power operation, and fast switching performance. Their inherent properties make them suitable for emerging applications such as neuromorphic computing, in-memory computing, and reservoir computing. However, the different applications demand either volatile or nonvolatile operation. In this study, we demonstrate how compliance current and specific material choices can be used to control the volatility and nonvolatility of memristive devices. Especially, by mixing different materials in the active electrode, we gain additional design parameters that allow us to tune the devices for different applications. We found that alloying Ag with Sn stabilizes the nonvolatile retention regime in a reproducible manner. Additionally, our alloying approach improves the reliability, endurance, and uniformity of the devices. We attribute these advances to stabilization of the filament inside the switching medium by the inclusion of Sn in the filament structure. These advantageous properties of alloying were found by investigating a choice of six electrode materials (Ag, Cu, AgCu-1, AgCu-2, AgSn-1, AgSn-2) and three switching layers (SiO$_2$, Al$_2$O$_3$, HfO$_2$)

Ultralow-Power Atomic-Scale Tin Transistor with Gate Potential in Millivolt

After decades of continuous scaling, further advancement of complementary metal-oxide-semiconductor (CMOS) technology across the entire spectrum of computing applications is today limited by power dissipation, which scales with the square of the supply voltage. Here, an atomic-scale tin transistor is demonstrated to perform conductive switching between bistable configurations with on/off potentials <= 2.5 mV in magnitude. In addition to the low operation voltage, the channel length of the transistor is determined experimentally and with density-functional theory to be <= 1 nm because the atoms instead of electrons are information carriers in this device. The conductance at on-states of the bistable configurations varies between 1.2 G(0) to 197 G(0) (G(0) = 2e(2) h(-1), e stands for the electron charge and h for Planck's constant). Thus, the device can supply driving current from 1 to approximate to 375 mu A in magnitude for logic circuits with the drain-source dc voltage at decades of millivolts. The switching frequency of the atomic-scale tin transistor has reached 2047 Hz. Furthermore, the on/off potentials in millivolts can reduce the energy consumption in the interconnects of integrated circuits at least by approximate to 400 times. Therefore, the atomic-scale tin transistor has prospects in digital circuits with ultralow-power dissipation and can contribute to the sustainability of modern society.ISSN:2199-160

Voiceprint Identification for Limited Dataset Using the Deep Migration Hybrid Model Based on Transfer Learning

The convolutional neural network (CNN) has made great strides in the area of voiceprint recognition; but it needs a huge number of data samples to train a deep neural network. In practice, it is too difficult to get a large number of training samples, and it cannot achieve a better convergence state due to the limited dataset. In order to solve this question, a new method using a deep migration hybrid model is put forward, which makes it easier to realize voiceprint recognition for small samples. Firstly, it uses Transfer Learning to transfer the trained network from the big sample voiceprint dataset to our limited voiceprint dataset for the further training. Fully-connected layers of a pre-training model are replaced by restricted Boltzmann machine layers. Secondly, the approach of Data Augmentation is adopted to increase the number of voiceprint datasets. Finally, we introduce fast batch normalization algorithms to improve the speed of the network convergence and shorten the training time. Our new voiceprint recognition approach uses the TLCNN-RBM (convolutional neural network mixed restricted Boltzmann machine based on transfer learning) model, which is the deep migration hybrid model that is used to achieve an average accuracy of over 97%, which is higher than that when using either CNN or the TL-CNN network (convolutional neural network based on transfer learning). Thus, an effective method for a small sample of voiceprint recognition has been provided

Light-induced synthesis of 2H-azirines and its applications in organic chemistry

2H-azirines have represented versatile building motifs in the domain of organic chemistry owing to their excellent reaction activity induced by the high strain of the three-membered ring species. Over the past decades, brilliant achievements have been made in 2H-azirine chemistry involving the construction as well as the transformation of such functional compounds. In the presence of transition metals, strong bases or oxidants, 2H-azirines could be converted into the corresponding products under harsh reaction conditions. Different from traditional catalytic methods, the utilization of photochemistry has proved to be an extremely fascinating protocol that facilitates the construction of 2H-azirine blocks from diverse substrates and further conversion into various derivatives with interesting biological activities. In this regard, more and more light-driven synthetic approaches featuring high efficiency and mild conditions have been developed. Herein, we summarized the accessibility and applications of 2H-azirines as powerful precursors or key intermediates for the synthesis of biologically promising molecules in the presence of photocatalytic conditions

Exchange processes in the contact formation of Pb electrodes

Motivated by recent experiments on electrochemically controlled Pb atomic-scale switches we have studied the self-diffusion of Pb on flat and stepped surfaces since diffusion processes play an important role in the growth of metal substrates. Kinetic modelling based on Monte-Carlo simulations using a model potential suggests that exchange processes play an important role in the contact formation at the nanoscale. Periodic density functional theory indeed find that the barriers for exchange diffusion across the steps are significantly lower than for hopping diffusion. The consequences for the contact formation in electrochemically controlled switches are discussed

Copper atomic-scale transistors

We investigated copper as a working material for metallic atomic-scale transistors and confirmed that copper atomic-scale transistors can be fabricated and operated electrochemically in a copper electrolyte (CuSO4 + H2SO4) in bi-distilled water under ambient conditions with three microelectrodes (source, drain and gate). The electrochemical switching-on potential of the atomic-scale transistor is below 350 mV, and the switching-off potential is between 0 and −170 mV. The switching-on current is above 1 μA, which is compatible with semiconductor transistor devices. Both sign and amplitude of the voltage applied across the source and drain electrodes (Ubias) influence the switching rate of the transistor and the copper deposition on the electrodes, and correspondingly shift the electrochemical operation potential. The copper atomic-scale transistors can be switched using a function generator without a computer-controlled feedback switching mechanism. The copper atomic-scale transistors, with only one or two atoms at the narrowest constriction, were realized to switch between 0 and 1G0 (G0 = 2e2/h; with e being the electron charge, and h being Planck’s constant) or 2G0 by the function generator. The switching rate can reach up to 10 Hz. The copper atomic-scale transistor demonstrates volatile/non-volatile dual functionalities. Such an optimal merging of the logic with memory may open a perspective for processor-in-memory and logic-in-memory architectures, using copper as an alternative working material besides silver for fully metallic atomic-scale transistors

Copper atomic-scale transistors

We investigated copper as a working material for metallic atomic-scale transistors and confirmed that copper atomic-scale transistors can be fabricated and operated electrochemically in a copper electrolyte (CuSO4 + H2SO4) in bi-distilled water under ambient conditions with three microelectrodes (source, drain and gate). The electrochemical switching-on potential of the atomic-scale transistor is below 350 mV, and the switching-off potential is between 0 and −170 mV. The switching-on current is above 1 μA, which is compatible with semiconductor transistor devices. Both sign and amplitude of the voltage applied across the source and drain electrodes (Ubias) influence the switching rate of the transistor and the copper deposition on the electrodes, and correspondingly shift the electrochemical operation potential. The copper atomic-scale transistors can be switched using a function generator without a computer-controlled feedback switching mechanism. The copper atomic-scale transistors, with only one or two atoms at the narrowest constriction, were realized to switch between 0 and 1G0 (G0 = 2e2/h; with e being the electron charge, and h being Planck’s constant) or 2G0 by the function generator. The switching rate can reach up to 10 Hz. The copper atomic-scale transistor demonstrates volatile/non-volatile dual functionalities. Such an optimal merging of the logic with memory may open a perspective for processor-in-memory and logic-in-memory architectures, using copper as an alternative working material besides silver for fully metallic atomic-scale transistors.ISSN:2190-428

MEMS Plasmonics and Memristive Plasmonics for Optical Communications

Plasmonics allows for an unmatched miniaturization. Along with the shrinking comes power efficient operation. Here, we show how plasmonics allows for an unprecedented downscaling of the classical MEMS and even of emerging memristive approaches. Ultimately, we will demonstrate optical elements at the atomic scale