Skeparovski, Aleksandar
Preferred name
Skeparovski, Aleksandar
Official Name
Skeparovski, Aleksandar
Main Affiliation
Email
skepalek@pmf.ukim.mk
7 results
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Item type:Publication, PROGRESS IN MATERIALS FOR MICROELECTRONICS AND FURTHER CHALLENGES(Macedonian Academy of Sciences and Arts, 2017-04-10); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Properties of surface electronic states in layered organic conductors in out-of-plane magnetic field(World Scientific Pub Co Pte Ltd, 2022-08-25); ; Gjorgjevski, Milan<jats:p> In this paper, we have considered the properties of surface electronic states in quasi-two-dimensional organic conductors for an out-of-plane orientation of the magnetic field. The energies of these states have be calculated which allow the resonance magnetic fields and resonance angles corresponding to the positions of the peaks in oscillation spectra of surface resistance to be determined. We find that the energies of the magnetic-field induced surface states are decreasing significantly with increasing tilt angle from the surface. This is related to the fact that the surface states are realized due to electron transitions between different in size elliptical closed orbits obtained as cross-section of the Fermi surface with the plane [Formula: see text], [Formula: see text] const. In comparison to the case of in-plane magnetic field, where only the small closed orbits on the sides of the Fermi surface are involved in formation of the surface states, for out-of-plane magnetic field there are additionally present other, larger orbits that are spanning across the Fermi surface. We also find that the coordinate of the center of electron revolution is increasing significantly with increasing tilt angle but the maximum distance from the surface for the electrons involved in the surface states shows a steady increase indicating that the skipping trajectories are well confined within skin layer of the conductor. This indicates that the surface states can be observed for almost each field direction from the surface including those with higher quantum number. These studies allow to determine more accurately certain Fermi surface parameters such as the local radius of curvature in the plane perpendicular to the magnetic field as well as the Fermi velocity at each point on the elliptical cross-sections. We are highly convinced that our results will motivate new experimental investigations of surface phenomena in order to exploit the properties of surface electronic states for various scientific applications. </jats:p> - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Surface-state energies and wave functions in layered organic conductors(Walter de Gruyter GmbH, 2020-11-26); We have calculated and analyzed the surface-state energies and wave functions in quasi-two dimensional (Q2D) organic conductors in a magnetic field parallel to the surface. Two different forms for the electron energy spectrum are used in order to obtain more information on the elementary properties of surface states in these conductors. In addition, two mathematical approaches are implemented that include the eigenvalue and eigenstate problem as well as the quantization rule. We find significant differences in calculations of the surface-state energies arising from the specific form of the energy dispersion law. This is correlated with the different conditions needed to calculate the surface-state energies, magnetic field resonant values and the surface wave functions. The calculations reveal that the value of the coordinate of the electron orbit must be different for each state in order to numerically calculate the surface energies for one energy dispersion law, but it has the same value for each state for the other energy dispersion law. This allows to determine more accurately the geometric characteristics of the electron skipping trajectories in Q2D organic conductors. The possible reasons for differences associated with implementation of two distinct energy spectra are discussed. By comparing and analyzing the results we find that, when the energy dispersion law obtained within the tight-binding approximation is used the results are more relevant and reflect the Q2D nature of the organic conductors. This might be very important for studying the unique properties of these conductors and their wider application in organic electronics.</jats:p> - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Einstein's mirror revisited(American Association of Physics Teachers (AAPT), 2007-01-19); We describe a simple geometrical derivation of the formula for reflection of light from a uniformly moving plane mirror directly from the postulates of special relativity. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Ultraviolet Photodetector Based on Mg 0.67 Ni 0.33 O Thin Film on SrTiO 3(Wiley, 2020-05-20); Lazarov, Vlado K.Herein, a new heterostructured ultraviolet metal–semiconductor–metal photodetector based on Mg0.67Ni0.33O thin film and SrTiO3 is reported. The metal–semiconductor–metal photodetector comprises a 22 nm epilayer of Mg0.67Ni0.33O grown on SrTiO3 (111) substrate by molecular beam epitaxy. A comparison of responsivities of the Mg0.67Ni0.33O–SrTiO3 photodetector and reference SrTiO3 photodetector shows that the heterostructured detector has close to an order of magnitude enhanced responsivity in the deep‐ultraviolet region. The responsivity of the Mg0.67Ni0.33–SrTiO3‐based photodetector at 320 nm is 415 mA W−1, with dark current lower than 40 pA at a bias of 10 V. The rise and fall times of Mg0.67Ni0.33O–SrTiO3 photodetector are 10.7 and 8.6 ms, respectively, with the rise time more than two orders of magnitude shorter than the reference SrTiO3 photodetector. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Magnetic oscillation spectrum of surface resistance in layered organic compounds(IOP Publishing, 2023-02-14); <jats:title>Abstract</jats:title> <jats:p>The magnetic quantum oscillations of surface resistance in quasi-two dimensional layered organic conductors have been obtained numerically for a magnetic field parallel to the surface. The resonance fields, which were theoretically calculated in a previous work on surface states, are found to coincide closely to the positions of the maxima in the ∂<jats:italic>R</jats:italic>/∂<jats:italic>B</jats:italic> curves. We find that, in quasi-two dimensional organic conductors, the transitions between the adjacent surface states are the most present transitions in the sum curve for surface resistance derivative oscillation spectrum. Our results, obtained from the calculations of the oscillation spectra of the individual series and the sum of six series, confirm that the theoretical description of surface states in the anisotropic organic conductors is essentially correct in its numerical aspects. These studies will be very helpful for analyzing and explaining the experimental curves and for their comparison with the theoretical results. Since there are yet no experimental data on surface impedance oscillations in quasi-two dimensional organic conductors with this work we would like to shed new light on this problem in order to motive new research in that direction mostly because of a need of such studies for a possible utilization of surface effects in the existing organic devices.</jats:p> - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Analysis of Conduction and Charging Mechanisms in Atomic Layer Deposited Multilayered HfO2/Al2O3 Stacks for Use in Charge Trapping Flash Memories(Hindawi Limited, 2018); ; Spassov, DenchoMethod for characterization of electrical and trapping properties of multilayered high permittivity stacks for use in charge trapping flash memories is proposed. Application of the method to the case of multilayered HfO2/Al2O3 stacks is presented. By applying our previously developed comprehensive model for MOS structures containing high- dielectrics on the characteristics measured in the voltage range without marked degradation and charge trapping (from −3 V to +3 V), several parameters of the structure connected to the interfacial layer and the conduction mechanisms have been extracted. We found that the above analysis gives precise information on the main characteristics and the quality of the injection layer. characteristics of stressed (with write and erase pulses) structures recorded in a limited range of voltages between −1 V and +1 V (where neither significant charge trapping nor visible degradation of the structures is expected to occur) were used in order to provide measures of the effect of stresses with no influence of the measurement process. Both trapped charge and the distribution of interface states have been determined using modified Terman method for fresh structures and for structures stressed with write and erase cycles. The proposed method allows determination of charge trapping and interface state with high resolution, promising a precise characterization of multilayered high permittivity stacks for use in charge trapping flash memories.