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A large area array of metal-oxide-metal (MOM) tunneling diodes with an ultrathin dielectric (∼3.6 nm aluminum oxide) have been fabricated via a transfer-printing process. The MOM diodes exhibit an excellent tunneling behavior that is suitable for rectifying high-frequency ac current into direct current (dc). Direct tunneling and Fowler-Nordheim tunneling have been observed over eight orders of magnitude in current density. The ratio between forward and reverse current is as large as two orders of magnitude. Simulations have been carried out to extract the static device parameters and have confirmed the existence of a dipole layer at the aluminum/aluminum oxide interface of the printed tunneling diodes. Capacitance measurements have shown that the permittivity of the ultrathin aluminum oxide film is smaller than that of bulk aluminum oxide. The mechanical yield of the transfer-printing process is better than 80%, confirming that transfer printing is a promising candidate for the efficient fabrication of quantum devices over large areas. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the influence of electrode roughness on the leakage current in TiN/high-κ ZrO2/TiN (TZT) thin-film capacitors which are used in dynamic random access memory cells. Based on a microscopic transport model, which is expanded to incorporate electrode roughness, we assess the ultimate scaling potential of TZT capacitors in terms of equivalent oxide thickness, film smoothness, thickness fluctuations, defect density and distribution, and conduction band offset (CBO). The model is based on three-dimensional, fully self-consistent, kinetic Monte Carlo transport simulations. Tunneling transport in the bandgap of the dielectric is treated, which includes defect-assisted transport mechanisms. Electrode roughness is described in the framework of fractal geometry. While the short-range roughness of the electrodes is found not to influence significantly the leakage current, thickness fluctuations of the dielectric have a major impact. For thinner dielectric films they cause a transformation of the dominant transport mechanism from Poole-Frenkel conduction to trap-assisted tunneling. Consequently, the sensitivity of the leakage current on electrode roughness drastically increases on downscaling. Based on the simulations, optimization of the CBO is suggested as the most viable strategy to extend the scalability of TZT capacitors over the next chip generations. [ABSTRACT FROM AUTHOR]

In this paper, we have investigated the leakage current versus voltage characteristic of high- k thin film capacitors over a large temperature range. Fabricated samples, consisting of a 10-nm thin {\rm SrTiO}_{3} (STO) layer as a dielectric material and {\rm SrRuO}_{3}$ as electrodes, have been examined. Electrical measurements performed at different temperatures reveal leakage currents that exceed 10^{-7}~{\rm A}/{\rm cm}^{2} at 1 V, a requirement needed for dynamic random access memory (DRAM) applications. We perform a detailed simulation study for the measured samples, making use of a modified drift diffusion model, which also takes into account charge trapping/detrapping effects and nonlocal tunneling. Based on our simulations, we propose an explanation for the large leakage currents observed experimentally. They can be attributed to a trap-assisted tunneling process that is enhanced by oxygen vacancies in the STO dielectric layer. We are thus able to reproduce the temperature and voltage dependence of the measured currents and can use our model to examine the impact of different physical parameters on the behavior of the capacitor structure—a first step toward device optimization. A feasibility analysis is performed for a 1T1C DRAM cell using an optimized deep trench STO capacitor with a reduced oxygen defect density. The simulation results underline the advantages of our modeling procedure using a commercial technology computer aided design (TCAD) framework: once the complex leakage mechanism is implemented, it can be activated on arbitrary 3-D structures, taking advantage of all the postprocessing or visualization capabilities. [ABSTRACT FROM AUTHOR]

We assess the impact of structural relaxation of defects upon charging on trap-assisted tunneling in high-κ dielectric materials. Zr02/Al203/Zr02 thin films are taken as an exemplary system. In our completely different approach, a first-principles defect model is derived from Hedins GW approximation calculations, which is then coupled to kinetic Monte Carlo charge transport simulations. Comparison between simulation and experiment demonstrates that it is often imperative to take structural relaxation processes into account when modeling nanoscale transport across defect states. [ABSTRACT FROM AUTHOR]

Leakage currents in \TiN/\high-\kappa\-ZrO2/ \TiN capacitors were simulated by using a novel kinetic Monte Carlo algorithm specially designed to describe tunneling transport of charge carriers in high-\kappa dielectrics, including defect-assisted transport mechanisms. Comparing simulation results with experimental data, a model for electronic transport was established and validated. Transport was found to be dominated by Poole–Frenkel emission from positively charged bulk trap states at medium voltages and trap-assisted tunneling at high voltages. Information on the conduction band offset at the \TiN/ZrO2 interface as well as on the trap depth was extracted. The model accurately describes the scaling of the leakage current with temperature and with thickness of the dielectric film, and it provides insight into the mutual interdependence of the competing transport mechanisms. [ABSTRACT FROM AUTHOR]

Nanoscale metal-insulator-metal (MIM) diodes represent important devices in the fields of electronic circuits, detectors, communication, and energy, as their cutoff frequencies may extend into the "gap" between the electronic microwave range and the optical long-wave infrared regime. In this paper, we present a nanotransfer printing method, which allows the efficient and simultaneous fabrication of large-scale arrays of MIM nanodiode stacks, thus offering the possibility of low-cost mass production. In previous work, we have demonstrated the successful transfer and electrical characterization of macroscopic structures. Here, we demonstrate for the first time the fabrication of several millions of nanoscale diodes with a single transfer-printing step using a temperature-enhanced process. The electrical characterization of individual MIM nanodiodes was performed using a conductive atomic force microscope (AFM) setup. Our analysis shows that the tunneling current is the dominant conduction mechanism, and the electrical measurement data agree well with experimental data on previously fabricated microscale diodes and numerical simulations., (© 2012 American Chemical Society)