Confinement induced instability of thin elastic film

A confined incompressible elastic film does not deform uniformly when subjected to adhesive interfacial stresses but with undulations which have a characteristic wavelength scaling linearly with the thickness of the film. In the classical peel geometry, undulations appear along the contact line below a critical film thickness or below a critical curvature of the plate. Perturbation analysis of the stress equilibrium equations shows that for a critically confined film the total excess energy indeed attains a minima for a finite amplitude of the perturbations which grow with further increase in the confinement.Comment: 11 pages, 6 figure

Size distribution of sputtered particles from Au nanoislands due to MeV self-ion bombardment

Nanoisland gold films, deposited by vacuum evaporation of gold onto Si(100) substrates, were irradiated with 1.5 MeV Au$^{2+}$ ions up to a fluence of $5\times 10^{14}$ ions cm$^{-2}$ and at incidence angles up to $60^{\circ}$ with respect to the surface normal. The sputtered particles were collected on carbon coated grids (catcher grid) during ion irradiation and were analyzed with transmission electron microscopy and Rutherford backscattering spectrometry. The average sputtered particle size and the areal coverage are determined from transmission electron microscopy measurements, whereas the amount of gold on the substrate is found by Rutherford backscattering spectrometry. The size distributions of larger particles (number of atoms/particle, $n$ $\ge$ 1,000) show an inverse power-law with an exponent of $\sim$ -1 in broad agreement with a molecular dynamics simulation of ion impact on cluster targets.Comment: 13 pages, 8 figures, Submitted for publication in JA

Jednostavna teorijska analiza kapacitancije magnetskih vrata u MOS strukturi p-kanalnog inverzijskog sloja na teluru

An attempt is made to study the gate capacitance of MOS structure of p-channel inversion layers on tellurium in the presence of a quantizing magnetic field by considering all types of anisotropies of the valence bands of tellurium within the framework of k^→ · p^→ theory. We have derived an analytical expression of the surface electron concentration in low electric field limit in the presence of a quantizing magnetic field. We have then formulated a model expression of the magneto-gate capacitance with the proper use of the electron concentration. For the purpose of relative comparison, we have also derived the same capacitance by including the broadening effects and without any approximations of low or high electric field limits. It has been observed that the gate capacitance of p-channel inversion layers on tellurium exhibits spiky oscillations with changing magnetic field. The corresponding well-known results for p-channel inversion layers on parabolic energy bands have also been obtained under certain limiting conditions from the generalized expressions.Proučavaju se kapacitancija vrata MOS strukture p–kanalnih inverzijskih slojeva na teluru u magnetskom polju na osnovi k^→ · p^→ teorije. Pokazuje se da kapacitancija vrata mijenja periodički s rastućim magnetskim poljem. Dobiveni rezultati svode se u modelu paraboličkih vrpci, uz određene uvjete, na poznate izraze

Einsteinova relacija u superrešetkama poluvodiča s ne-paraboličnim vrpcama i neoštrim međuplohama kod magnetske kvantizacije

We study the Einstein relation under magnetic quantization in III-V, II-VI, PbSnTe/PbTe, strained layer and HgTe/CdTe superlattices with graded interfaces and compare the same with that of the corresponding bulk specimens of the constituent materials. It is found, taking GaAs/Ga1-xAlxAs, CdS/CdTe, PbTe/PbSnTe, InAs/GaSb and HgTe/CdTe superlattices with graded interfaces as examples, that the Einstein relation exhibits oscillatory dependence with the inverse quantizing magnetic field due to the Shubnikov-de Haas effect, and increases with increasing electron concentration in an oscillatory manner in all the cases. The ratio of diffusivity to mobility in graded superlattices is greater than that of constituent bulk materials. The oscillations in HgTe/CdTe superlattices show up much more significantly as compared to other systems. In addition, we have suggested an experimental method of determining the Einstein relation in degenerate materials having arbitrary dispersion laws.Razmatrana je Einsteinova relacija kod magnetske kvantizacije u superrešetkama s neoštrim međuplohama III-V i II-VI poluvodiča, PbSnTe/PbTe, HgTe/CdTe te slojeva s napetošću, te je usporedena s onom u volumnim uzorcima gradbenih materijala. Nadeno je, uzevši GaAs/Ga1−xAlxAs, CdS/CdTe, PbTe/PbSnTe, InAs/GaAs i HgTe/CdTe superrešetke s neoštrim međuplohama kao primjer, da Einsteinova relacija pokazuje oscilatornu zavisnost o inverznim kvantizirajućim magnetskim poljima kao posljedica Shubnikov-de Haas efekta te raste oscilatorno s porastom koncentracije elektrona u svim slučajevima. Omjer difuzivnosti i pokretnosti je veći nego u volumnim uzorcima gradbenih materijala. Oscilacije u HgTe/CdTe superrešetkama su izrazitije nego u drugim uzorcima. Također, predložena je eksperimentalna metoda određivanja Einsteinove relacije u degeneriranim materijalima s proizvoljnim zakonom disperzije

Utjecaj kvantnog zasužnjenja na toplinski kapacitet grafita

In this paper an attempt is made to investigate theoretically the heat capacity in graphite having quantum confinement in one, two and three dimensions such as quantum wells, quantum wires, quantum dots and magneto-sized quantization of band states. The appropriate density of states functions are deduced, taking into account various types of anisotropies of the energy band constants. It has been found that the heat capacity oscillates with the film thickness, magnetic film and doping in various manners. The heat capacity is largest in quantum dots and smallest in quantum wells. The theoretical analysis is in agreement with the experimental results.Pokušava se objasniti toplinski kapacitet grafita u kojem postoji kvantno zasužnjenje u jednoj, dvije ili tri dimenzije, tj. u kvantnim jamama, kvantnim žicama, kvantnim točkama, te sistemima s magnetski-ograničenom kvantizacijom stanja vrpci zaključivanjem o odgovarajućem obliku funkcije gustoće stanja. Pri tome se uzimaju u obzir razni oblici anizotropije konstanti energetskih vrpci. Nadeno je da toplinski kapacitet titra kao funkcija debljine sloja, magnetskog polja i dopiranja. Toplinski kapacitet je najveći u kvantnim točkama, a najmanji u kvantnim jamama. Teorijska analiza u skladu je s rezultatima mjerenja