Milos Marjanovic

On the Recoverable and Permanent Components of NBTI in p-Channel Power VDMOSFETs

This paper introduces a new experimental approach allowing to investigate the recoverable and permanent components in commercial p-channel power VDMOSFETs subjected to negative bias temperature (NBT) stressing. In many applications, devices can be used in multiple modes, which include application of static or pulsed gate voltages at different stages of device operation. Accordingly, we have investigated stress-induced degradation in the cases where the static stress was followed by the pulsed NBT stress conditions and vice versa. The results are discussed in terms of the mechanisms responsible for the buildup of oxide charge and interface traps. It has been shown that the differences in the permanent components of the oxide charge and interface traps between devices exposed to static stress followed by pulsed NBT stress and those exposed only to static NBT stress tend to decrease during the pulsed stress as the duty cycle increases but cannot be completely removed.

Characterization and SPICE Modeling of Passive Electronic Devices at High Frequencies

In this paper the results of characterization and modeling of passive electronic devices (capacitors and inductors) have been presented. The experimental results obtained using RF impedance analyzer have been discussed, and based on them, parameters of equivalent circuits have been determined using analytical model. Approximate functions for parasitic elements of the devices have been proposed.

Electrical Characteristics of Nb Doped BaTiO3 Ceramics

The Nb doped BaTiO3 ceramics, with different Nb2O5 content, ranging from 0.5 to 2.0 at.% Nb, is investigated regarding their microstructure and electrical characteristics in this paper. The Nb/BaTiO3 ceramics is prepared by the conventional solid state reaction and sintered at 1320 °C in an air atmosphere for 2 h. As acceptor dopant Mn in concentration of 0.01 mol% is added. For low doped samples (0.5 mol% Nb), the characteristic is homogeneous and fine grained microstructure with grain size from 0.5 to 2 μm. Increasing the additive content results in the grain size increasing so that the samples doped with 2.0 mol% Nb the average grain size reaches 10 μm. The dielectric characteristic of Nb doped BaTiO3 ceramics like dielectric constant, dissipation factor and resistivity have been measured by using LCR-Meter Agilent 4284A in the frequency range 20 Hz–1 MHz and Agilent E4991A RF Impedance/Material Analyzer for high frequency measurements (1 MHz–3 GHz). Dielectric constant and tangent losses after initial large values remains nearly independent of frequency greater than 10 kHz. Dielectric measurements were carried out as a function of temperature up to 180 °C. The low doped samples (0.5Nb/BaTiO3) sintered at 1320 °C, display the high value of dielectric permittivity at room temperature, e r = 3225. A nearly flat permittivity-temperature response is obtained in specimens with 2.0 at.% additive content. The Curie–Weiss and modified Curie–Weiss law is used to clarify the influence of dopant on the dielectric properties and BaTiO3 phase transformation. All investigated samples have an electrical resistivity ρ > 106 Ωcm at room temperature. New aspect here is fractal correction, introduced as slight variation of temperature T entered from outside, due to three fractal factors α S , α P and α M being responsible for complex geometry of both morphologic and dynamic nature. This correction, naturally has impact on the Curie–Weiss low, which is stressed in this paper.

High frequency characterization and modelling of ceramic capacitors

In this paper the results of characterization and modelling of capacitors have been presented. The experimental results obtained using RF impedance analyzer have been discussed, and based on them, parameters of equivalent circuits have been determined using analytical model. Approximate functions for parasitic elements of the device have been proposed.