PHYSICAL MODELING OF ELECTRICAL AND DIELECTRIC PROPERTIES OF HIGH-k Ta2O5 BASED MOS CAPACITORS ON SILICON

In this paper we present an integral physical model for describing electrical and dielectric properties of MOS structures containing dielectric stack composed of a high-k dielectric (with emphasize on pure and doped Ta2O5) and an interfacial silicon dioxide or silicon oxynitride layer. Based on the model, an equivalent circuit of the structure is proposed. Validity of the model was demonstrated for structures containing different metal gates (Al, Au, Pt, W, TiN, Mo) and different Ta2O5 based high-k dielectrics, grown of bare or nitrided silicon substrates.The model describes very well the I-V characteristics of the considered structures, as well as frequency dependence of the capacitance in accumulation. Stress-induced leakage currents are also effectively analyzed by the use of the model

Frequency Dependence of C

Capacitance of metal–insulator–Si structures containing high permittivity dielectric exhibits complicated behaviour when voltage and frequency dependencies are studied. From our study on metal (Al, Au, W)–Ta2O5/SiO2–Si structures, we identify serial C-R measurement mode to be more convenient for use than the parallel one usually used in characterization of similar structures. Strong frequency dependence that is not due to real variations in the dielectric permittivity of the layers is observed. Very high capacitance at low frequencies is due to the leakage in Ta2O5 layer. We found that the above observation is mainly due to different leakage current mechanisms in the two different layers composing the stack. The effect is highly dependent on the applied voltage, since the leakage currents are strongly nonlinear functions of the electric field in the layers. Additionally, at low frequencies, transition currents influence the measured value of the capacitance. From the capacitance measurements several parameters are extracted, such as capacitance in accumulation, effective dielectric constant, and oxide charges. Extracting parameters of the studied structures by standard methods in the case of high-κ/interfacial layer stacks can lead to substantial errors. Some cases demonstrating these deficiencies of the methods are presented and solutions for obtaining better results are proposed

New geomagnetic measurements in the Republic of Macedonia

This study presents measurements of the geomagnetic field of the Republic of Macedonia, performed through a network of newly defined repeat stations. The measurements of these elements were in the intervals of 3.378° ≤ DD ≤ 3.983°, 57.276° ≤ I ≤ 59.005°, and 46 235 nT ≤ F ≤ 46903 nT. The geomagnetic data were processed and the results of the observed elements of the geomagnetic field on the repeat stations are presented. Additional data processing was performed to calculate the reduced values of the intensive elements of the field at the level of H500 a.s.l.. Based on these data, new maps of the geomagnetic field of the Republic of Macedonia are developed, together with the polynomial model of the elements of the geomagnetic field for the 2010.0 epoch

Analysis of Conduction and Charging Mechanisms in Atomic Layer Deposited Multilayered HfO 2

Method 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-κ dielectrics on the J-V 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. C-V 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

Structure of the geomagnetic field in correlation with neotectonic regionalization of the Republic of Macedonia

The paper presents research of the structure of the geomagnetic field in correlation with the neotectonic regionalization. The territory of the Republic of Macedonia, according to the neotectonic processes, is divided in three zones: Western - Macedonian zone which include Alpine orogeny and Pelagonian massif, Vardar zone and Eastern - Macedonian zone which is part of the old Paleozioc rock mass on the Balkan Peninsula. Anomalous geomagnetic field on the territory of the Republic of Macedonia is presented with regional and local components. Selection of the repeat stations density and the method for data processing is adapted to separate the regional from the local component of the anomalous geomagnetic field. The paper presents maps of the elements of the regional anomalous geomagnetic field and the map of the Z - component for the local field