Electromigration has gained increased prominence in recent years, as semiconductor device scaling has given way to higher current and power densities in computing interconnects and devices. The conventional understanding of electromigration has remained at an uneasy juncture between the mesoscopic semiclassical and atomistic quantum mechanical regimes. Herein, an “atomistic semiclassical” interpretation of electromigration is presented in an attempt to bridge these two perspectives at the nanoscale.

We analyze the interplay between anomalous transport and conversion reaction kinetics in mesoporous materials functionalized with catalytic groups. Of primary interest is functionalized mesoporous silica containing an array of linear pores with diameters tunable from 2-10 nm, although functionalization can produce smaller effective diameters, d. For d < 2 nm, transport and specifically passing of reactant and product species within the pores can be strongly inhibited (single-file diffusion). The distribution of catalytic groups can also vary depending on the synthesis approach. We apply statistical mechanical modeling (utilizing spatially discrete stochastic lattice-gas models) to explore the dependence of reactivity on the extent of inhibition of passing of species within the pore, as well as on the distribution of catalytic sites.

Nitridation is the process in which, during the initial growth of a-SiNx:H layers on Si surfaces, nitrogen (N) is incorporated into Si lattice near its surface. We show that this nitridation process affects the density of interface states (Dit) and fixed charges (Qf) at the interface. These parameters determine the effective surface passivation quality of the layers. The nitridation can be tuned independently of the growth of a-SiNx:H layers by using a plasma treatment prior to actual a-SiNx:H layer deposition. It is shown that the Qf can be varied from 2·1012 to 15·1012 cm-2 without changing the a-SiNx:H deposition process. It is demonstrated that in our case and processing window, Qf is the determining factor in surface passivation quality in the range of 2·1012 to 8·1012 cm-2. For higher values of Qf, Dit has increased significantly and has become dominant thereby reducing the passivation quality. It is shown that the passivation can be controlled independently of the a-SiNx:H deposition process. On completed solar cells this variation in Qf due to nitridation results in a change in open-circuit voltage, Voc, of almost 20mV.

We theoretically study the spatial and temporal fluctuation of two electrons confined in a semiconductor quantum dot (QD). Eigenstates are determined by the resonating unrestricted Hartree-Fock (res-UHF) approach in order to take into account the electron correlation via the configuration interaction (CI). The time-dependent (TD) wave function is, then, expanded by the UHF solutions, and the CI treatment is combined with the TD Schrödinger equation (TD-CI). The present TD-CI approach has an advantage to study how the electron correlation fluctuates the multi-electron state spatially and/or temporally through the multi-reference description of many-electron wave functions.

The thickness of non-freezing interfacial 1-decanol molecules has been estimated to be 1.44 ± 0.07 nm. This is smaller than what is estimated for cyclohexane, 2.25 ± 0.14nm. Furthermore, these interfacial molecules have higher density than corresponding bulk cyclohexane and 1-decanol, respectively. However, the change in density of the interfacial molecules is more significant in the case of cyclohexane than 1-decanol. This suggests that the cyclohexane molecules near the walls of the pore are more tightly packed than 1-decanol molecules. Presumably, this is due to the difference in size and shape of the molecules. Cyclohexane, a more spherical molecule, can easily be packed in smaller pores than the longer 1-decanol.

The nano-scale friction on crystalline gold surfaces can be systematically varied by changing the oxidation state of the surfaces through an applied electrochemical potential. We present experimental results from high-resolution friction force microscopy, where the atomic structure of the surface is reflected in lateral force maps. While the oxidation of gold surfaces always brings upon a significant increase in friction, the situation is more complex in the potential regime where only sulfate anions are adsorbed. The influence of adsorbed anions on friction depends on electrochemical potential and on normal load, demonstrating that electrochemical processes and sliding dynamics are altered in the confinement of the tip-sample contact.