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In this paper, we present the implications that the Lightly Doped Drain-LDD technique used for Metal Oxide Semiconductor-MOS fabrication of n-channel transistor has on different device parameters. The discussion focuses on the influence of the n- doping of drain, respectively source on the electric field, one of the most important issues of today's technology, but takes also into consideration another...
Wide bandgap semiconductors such as silicon carbide, gallium nitride and diamond have been recently investigated in order to replace silicon in the power electronic domain. In this paper, silicon carbide devices are studied using an optical method. It consists on illuminating a reverse biased junction with a laser beam with an appropriate wavelength, and then measuring the induced current due to the...
Interface state density (Dit) at SiO2/4H-SiC interfaces is investigated using capacitance-voltage (C-V) characterization. Two different measurement methods for Dit determination (both C-V at different temperatures in the range of 80–300K and high frequency (HF) vs quasi static (QS) characteristics) have been used. A significant reduction of Dit is observed, almost one order of magnitude, after a post...
Excitation and propagation of surfaces waves in graphene are analyzed within a frequency band of 1 to 300 THz, and a time domain of 1 to 10 ps. An ab initio approach, based on time dependent density functional theory in linear response regime is used. The key outputs of the simulation are the ab-initio conductance in time and frequency. This is shown to tend to a continuous integral relations in graphene,...
A class of linear continuous in time and discrete in space homogeneous Cellular Neural Network (CNN) type analog parallel architecture and a 16 cells 1D CMOS implementation are discussed. The effect of charge injection is analyzed and experimental results for a low pass and stop band configuration are presented and compared to simulations.
The use of high power freewheeling diodes - Silicon Carbide Schottky and PiN rectifiers - in buck converter-based LED drivers is investigated. Applications biasing up to 60 LEDs at input voltages reaching 250V are developed for both diode types. Despite different switching behavior and dissipated power between freewheeling devices, experimental results show a significant converter driving capability...
The paper presents three approaches for frequency compensation in chopper offset-stabilized amplifiers with symmetrical passive RC notch filter with two cutoff frequencies. The filter has two cutoff frequencies: the chopping frequency itself and the fifth harmonic of the chopping frequency. The frequency compensation network is connected either at the input of the notch filter, or at its output, or...
This paper describes, based on a micromagnetic approach and experimental measurements, our advances in the handling and detection of magnetic nanoparticles used for biodetection in lab-on-a-chip devices. Structures made from nonmagnetic and magnetic materials are considered in this study and results that highlight the importance of the material nature and specific interaction between the beads and...
This paper continues our previous works about the integrated circuits development on the 4H-SiC semiconductor, based on finger gate MESFETs. It describes a comparator designed exclusively with normally-on MESFETs and epitaxial resistors. For this novel circuit design we have used the SPICE models previously extracted from devices further used for fabrication of functional complex analog and digital...
The charge storage properties of Ge nanocrystals-based MOS-like capacitors with tunnel and gate HfO2 are studied. HfO2/Ge/HfO2/Si trilayer structures were prepared by magnetron sputtering (in Ar) and subsequent rapid thermal annealing (650 °C). HfO2/Si structures were also prepared, some under similar conditions, while others were deposited in Ar:O2. TEM investigations and C-V measurements were performed...
This paper focuses on the analysis of limit cycles that appear on the output voltage of a DC-DC Buck converter. Typically, the output filter of the converter is designed in open-loop, considering the maximum allowable values for the output voltage and inductor current ripples. When closing the loop, the converter may exhibit unwanted periodic oscillations in steady state caused by the nonlinearities...
This paper presents novel circuit solutions for two issues related to the Enable control of low-dropout (LDO) voltage regulators: setting precise voltage thresholds for the ON/OFF states of the LDO and ensuring that in the OFF state the LDO output is not affected by fast variations of the supply voltage. First, an Enable circuit with hysteresis and temperature compensated thresholds is described:...
CdSe thin films have been prepared by close spaced sublimation technique. The deposited films have been characterized by Scanning Electronic Microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD patterns have been used to determine the microstructural parameters (crystallite size, lattice parameter) of investigated films. Structural investigations showed that studied...
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