Structural characteristics of electrodeposited copper coatings

Uzorci bakra su podvrgnuti mehaničkom i elektrohemijskom glačanju u odgovarajućim elektrolitima za elektrohemijsko glačanje. Na tako prethodno pripremljene površine supstrata izvršeno je taloţenje prevlaka bakra iz dva kupatila i to iz osnovnog elektrolita (OR) sastava: 240 g/dm3 CuSO4 ∙ 5 H2O + 60 g/dm3 H2SO4 i kupatila sa dodacima za sjaj (OR +DS). Pomoću STM i AFM tehnika precizno su prikazane strukturne osobine koje odreĎuju da li je metalna površina ogledalski sjajna ili ne, odnosno da li dobijena topografija površine manje ili više hrapava. UtvrĎeno je znatno povećanje hrapavosti uzoraka na koje je taloţena prevlaka bakra iz osnovnog sulfatnog kupatila (OR) u odnosu na mehanički i mehanički i elektrohemijske pripremane uzorke. TakoĎe, pri taloţenju prevlaka iz kupatila sa dodacima za sjaj (OR +DS), došlo je do smanjenja hrapavosti površine.The samples of rolled copper were mechanically and electrochemically polished in suitable electrolytes for electrochemical polishing. These substrate surfaces that had been prepared in advance, served as the basis for depositing of copper layers from two baths, namely, from the basic electrolyte(OR) with the following composition: 240 g/dm3 CuSO4 ∙ 5 H2O + 60 g/dm3 H2SO4i as well as from the bath which contained brightening addition agents(OR +DS). STM and AFM techniques show in great detail the structural properties which determine whether the metal surfaceis are as bright as a mirrior or not, that is, whether the obtained topography of the surface is more or less rough. It was determined that a considerable increase of roughness occurred in the samples where copper layers were deposited from the basic sulfate bath (OR) when compared with mechanical, and mechanical-electrochemical samples. In addition, depositing of the samples from the bath with brightening addition agents (OR +DS) resulted in the decrease of surface roughness

Conductance oscillations of a spin-orbit stripe with polarized contacts

We investigate the linear conductance of a stripe of spin-orbit interaction in a 2D electron gas; that is, a 2D region of length $\ell$ along the transport direction and infinite in the transverse one in which a spin-orbit interaction of Rashba type is present. Polarization in the contacts is described by means of Zeeman fields. Our model predicts two types of conductance oscillations: Ramsauer oscillations in the minority spin transmission, when both spins can propagate, and Fano oscillations when only one spin propagates. The latter are due to the spin-orbit coupling with quasibound states of the non propagating spin. In the case of polarized contacts in antiparallel configuration Fano-like oscillations of the conductance are still made possible by the spin orbit coupling, even though no spin component is bound by the contacts. To describe these behaviors we propose a simplified model based on an ansatz wave function. In general, we find that the contribution for vanishing transverse momentum dominates and defines the conductance oscillations. Regarding the oscillations with Rashba coupling intensity, our model confirms the spin transistor behavior, but only for high degrees of polarization. Including a position dependent effective mass yields additional oscillations due to the mass jumps at the interfaces.Comment: 8.5 pages, 9 figure

On measuring skewness and kurtosis

Skewness, Kurtosis, Estimates of moments,