Conductance

About: Conductance is a research topic. Over the lifetime, 8088 publications have been published within this topic receiving 235961 citations.

Ion irradiation of the native oxide/silicon surface increases the thermal boundary conductance across aluminum/silicon interfaces

Abstract: The thermal boundary conductance across solid-solid interfaces can be affected by the physical properties of the solid boundary. Atomic composition, disorder, and bonding between materials can result in large deviations in the phonon scattering mechanisms contributing to thermal boundary conductance. Theoretical and computational studies have suggested that the mixing of atoms around an interface can lead to an increase in thermal boundary conductance by creating a region with an average vibrational spectra of the two materials forming the interface. In this paper, we experimentally demonstrate that ion irradiation and subsequent modification of atoms at solid surfaces can increase the thermal boundary conductance across solid interfaces due to a change in the acoustic impedance of the surface. We measure the thermal boundary conductance between thin aluminum films and silicon substrates with native silicon dioxide layers that have been subjected to proton irradiation and post-irradiation surface cleaning procedures. The thermal boundary conductance across the Al/native oxide/Si interfacial region increases with an increase in proton dose. Supported with statistical simulations, we hypothesize that ion beam mixing of the native oxide and silicon substrate within $\ensuremath{\sim}2.2\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ of the silicon surface results in the observed increase in thermal boundary conductance. This ion mixing leads to the spatial gradation of the silicon native oxide into the silicon substrate, which alters the acoustic impedance and vibrational characteristics at the interface of the aluminum film and native oxide/silicon substrate. We confirm this assertion with picosecond acoustic analyses. Our results demonstrate that under specific conditions, a ``more disordered and defected'' interfacial region can have a lower resistance than a more ``perfect'' interface.

Anomalous transport in biased ac-driven Josephson junctions: Negative conductances

Abstract: We investigate classical anomalous electrical transport in a driven, resistively, and capacitively shunted Josephson junction device. Intriguing transport phenomena are identified in chaotic regimes when the junction is subjected to both a time-periodic (ac) and a constant biasing (dc) current. The dependence of the voltage across the junction on the dc exhibits a rich diversity of anomalous transport characteristics. In particular, depending on the chosen parameter regime, we can identify the so termed absolute negative conductance around zero dc bias, the occurrence of negative differential conductance, and, after crossing a zero conductance, the emergence of a negative nonlinear conductance in the nonequilibrium response regime remote from zero dc bias.

Influence of anisotropy on thermal boundary conductance at solid interfaces

Abstract: We investigate the role of anisotropy on interfacial transport across solid interfaces by measuring the thermal boundary conductance from 100 to 500 K across Al/Si and Al/sapphire interfaces with different substrate orientations. The measured thermal boundary conductances show a dependency on substrate crystallographic orientation in the sapphire samples (trigonal conventional cell) but not in the silicon samples (diamond cubic conventional cell). The change in interface conductance in the sapphire samples is ascribed to anisotropy in the Brillouin zone along the principal directions defining the conventional cell. This leads to resultant phonon velocities in the direction of thermal transport that vary nearly 40% based on crystallographic direction.

Conductance of Electrolyte Solutions

Abstract: The present article deals with methods and results of conductance studies with special reference to nonaqueous solvents, eg ethanol, dioxane, dimethylformamide, acetonitrile, nitromethane, and acetone, in some cases mixed with water, as well as NH3, SO2, I2, etc On the basis of a model in which the ions are represented as charged spheres and the solvent as a homogeneous isotropic medium, the conductance theory can (at least for low electrolyte concentrations) give a more or less complete representation of the problem A new statistical treatment of the transport problem confirms important results of this representation The present state of the investigation is finally outlined in a review of recent publications