Study of metal oxide-semiconductor capacitors with rf magnetron sputtering TiO(x) and TiO(x)N(y) gate dielectric layer

Metal oxide-semiconductor capacitors with TiO(x) deposited with different O(2) partial pressures (30%, 35%, and 40%) and annealed at 550, 750, and 1000 degrees C were fabricated and characterized. Fourier transform infrared, x-ray near edge spectroscopy, and elipsometry measurements were performed to characterize the TiO(x) films. TiO(x)N(y) films were also obtained by adding nitrogen to the gaseous mixture and physical results were presented. Capacitance-voltage (1 MHz) and current-voltage measurements were utilized to obtain the effective dielectric constant, effective oxide thickness, leakage current density, and interface quality. The results show that the obtained TiO(x) films present a dielectric constant varying from 40 to 170 and a leakage current density (for V(G)=-1 V, for some structures as low as 1 nA/cm(2), acceptable for complementary metal oxide semiconductor circuits fabrication), indicating that this material is a viable, in terms of leakage current density, highk substitute for current ultrathin dielectric layers. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3043537]

Study of reactive sputtering titanium oxide for metal-oxide-semiconductor capacitors

Metal oxide semiconductor (MOS) capacitors with titanium oxide (TiO(x)) dielectric layer, deposited with different oxygen partial pressure (30,35 and 40%) and annealed at 550, 750 and 1000 degrees C, were fabricated and characterized. Capacitance-voltage and current-voltage measurements were utilized to obtain, the effective dielectric constant, effective oxide thickness, leakage current density and interface quality. The obtained TiO(x) films present a dielectric constant varying from 40 to 170 and a leakage current density, for a gate voltage of - 1 V, as low as 1 nA/cm(2) for some of the structures, acceptable for MOS fabrication, indicating that this material is a viable high dielectric constant substitute for current ultra thin dielectric layers. (C) 2009 Elsevier B.V. All rights reserved.

Improved effective charge density in MOS capacitors with PECVD SiOxNy dielectric layer obtained at low RF power

In this work SiOxNy films are produced and characterized. Series of samples were deposited by the plasma enhanced chemical vapor deposition (PECVD) technique at low temperatures from silane (SiH4), nitrous oxide (N2O) and helium (He) precursor gaseous mixtures, at different deposition power in order to analyze the effect of this parameter on the films structural properties, on the SiOxNy/Si interface quality and on the SiOxNy effective charge density. In order to compare the film structural properties with the interface (SiOxNy/Si) quality and effective charge density, MOS capacitors were fabricated using these films as dielectric layer. X-ray absorption near-edge spectroscopy (XANES), at the Si-K edge, was utilized to investigate the structure of the films and the material bonding characteristics were analyzed through Fourier transform infrared spectroscopy (FTIR). The MOS capacitors were characterized by low and high frequency capacitance (C-V) measurements, in order to obtain the interface state density (D-it) and the effective charge density (N-ss). An effective charge density linear reduction for decreasing deposition power was observed, result that is attributed to the smaller amount of ions present in the plasma for low RF power. (C) 2008 Elsevier B.V. All rights reserved.

Superior electric double layer capacitors using ordered mesoporous carbons

This paper reports for the first time superior electric double layer capacitive properties of ordered mesoporous carbon (OMCs) with varying ordered pore symmetries and mesopore structure. Compared to commercially used activated carbon electrode, Maxsorb, these OMC carbons have superior capacitive behavior, power output and high-frequency performance in EDLCs due to the unique structure of their mesopore network, which is more favorable for fast ionic transport than the pore networks in disordered microporous carbons. As evidenced by N-2 sorption, cyclic voltammetry and frequency response measurements, OMC carbons with large mesopores, and especially with 2-D pore symmetry, show superior capacitive behaviors (exhibiting a high capacitance of over 180 F/g even at very high sweep rate of 50 mV/s, as compared to much reduced capacitance of 73 F/g for Maxsorb at the same sweep rate). OMC carbons can provide much higher power density while still maintaining good energy density. OMC carbons demonstrate excellent high-frequency performances due to its higher surface area in pores larger than 3 nm. Such ordered mesoporous carbons (OMCs) offer a great potential in EDLC capacitors, particularly for applications where high power output and good high-frequency capacitive performances are required. (C) 2005 Elsevier Ltd. All rights reserved.

An efficient method for optimal location and sizing of fixed and switched shunt capacitors in large distribution systems

This paper proposes a computationally efficient methodology for the optimal location and sizing of static and switched shunt capacitors in large distribution systems. The problem is formulated as the maximization of the savings produced by the reduction in energy losses and the avoided costs due to investment deferral in the expansion of the network. The proposed method selects the nodes to be compensated, as well as the optimal capacitor ratings and their operational characteristics, i.e. fixed or switched. After an appropriate linearization, the optimization problem was formulated as a large-scale mixed-integer linear problem, suitable for being solved by means of a widespread commercial package. Results of the proposed optimizing method are compared with another recent methodology reported in the literature using two test cases: a 15-bus and a 33-bus distribution network. For the both cases tested, the proposed methodology delivers better solutions indicated by higher loss savings, which are achieved with lower amounts of capacitive compensation. The proposed method has also been applied for compensating to an actual large distribution network served by AES-Venezuela in the metropolitan area of Caracas. A convergence time of about 4 seconds after 22298 iterations demonstrates the ability of the proposed methodology for efficiently handling large-scale compensation problems.

Development of fractional order capacitors based on electrolyte processes

In recent years, significant research in the field of electrochemistry was developed. The performance of electrical devices, depending on the processes of the electrolytes, was described and the physical origin of each parameter was established. However, the influence of the irregularity of the electrodes was not a subject of study and only recently this problem became relevant in the viewpoint of fractional calculus. This paper describes an electrolytic process in the perspective of fractional order capacitors. In this line of thought, are developed several experiments for measuring the electrical impedance of the devices. The results are analyzed through the frequency response, revealing capacitances of fractional order that can constitute an alternative to the classical integer order elements. Fractional order electric circuits are used to model and study the performance of the electrolyte processes.

Fabrication and investigation of three-dimensional ferroelectric capacitors for the application of FeRAM

Magdeburg, Univ., Fak. für Elektrotechnik und Informationstechnik, Diss., 2015

Correlation between charge transport and electroluminescence properties of Si-rich oxide/nitride/oxide-based light emitting capacitors.

The electrical and electroluminescence (EL) properties at room and high temperatures of oxide/ nitride/oxide (ONO)-based light emitting capacitors are studied. The ONO multidielectric layer is enriched with silicon by means of ion implantation. The exceeding silicon distribution follows a Gaussian profile with a maximum of 19%, centered close to the lower oxide/nitride interface. The electrical measurements performed at room and high temperatures allowed to unambiguously identify variable range hopping (VRH) as the dominant electrical conduction mechanism at low voltages, whereas at moderate and high voltages, a hybrid conduction formed by means of variable range hopping and space charge-limited current enhanced by Poole-Frenkel effect predominates. The EL spectra at different temperatures are also recorded, and the correlation between charge transport mechanisms and EL properties is discussed.

A Comaparison Study of EM and Physical Equivalent Circuit Modeling for MIM CMOS Capacitors

In this Letter a new physical model for metal-insulatormetal CMOS capacitors is presented. In the model the parameters of the circuit are derived from the physical structural details. Physical behaviors due to metal skin effect and inductance have been considered. The model has been confirmed by 3D EM simulator and design rules proposed. The model presented is scalable with capacitor geometry, allowing designers to predict and optimize quality factor. The approach has been verified for MIM CMOS capacitors

High Selectivity Filter Employing Stepped Impedance Resonators, Series Capacitors and Defected Ground Structures for Ultra Wide Band Applications

The paper presents a compact planar Ultra Wide Band ¯lter employing folded stepped impedance resonators with series capacitors and dumb bell shaped defected ground structures. An interdigital quarter wavelength coupled line is used for achieving the band pass characteristics. The transmission zeros are produced by stepped impedance resonators. The ¯lter has steep roll o® rate and good attenuation in its lower and upper stop bands, contributed by the series capacitor and defected ground structures respectively.

Multivariate analysis of the dielectric response of materials modeled using networks of resistors and capacitors

We discuss the modeling of dielectric responses of electromagnetically excited networks which are composed of a mixture of capacitors and resistors. Such networks can be employed as lumped-parameter circuits to model the response of composite materials containing conductive and insulating grains. The dynamics of the excited network systems are studied using a state space model derived from a randomized incidence matrix. Time and frequency domain responses from synthetic data sets generated from state space models are analyzed for the purpose of estimating the fraction of capacitors in the network. Good results were obtained by using either the time-domain response to a pulse excitation or impedance data at selected frequencies. A chemometric framework based on a Successive Projections Algorithm (SPA) enables the construction of multiple linear regression (MLR) models which can efficiently determine the ratio of conductive to insulating components in composite material samples. The proposed method avoids restrictions commonly associated with Archie’s law, the application of percolation theory or Kohlrausch-Williams-Watts models and is applicable to experimental results generated by either time domain transient spectrometers or continuous-wave instruments. Furthermore, it is quite generic and applicable to tomography, acoustics as well as other spectroscopies such as nuclear magnetic resonance, electron paramagnetic resonance and, therefore, should be of general interest across the dielectrics community.

Improvement of Routine Test Process of High Voltage Power Capacitors

The capacitor test process at ABB Capacitors in Ludvika must be improved to meet future demands for high voltage products. To find a solution to how to improve the test process, an investigation was performed to establish which parts of the process are used and how they operate. Several parts which can improves the process were identified. One of them was selected to be improved in correlation with the subject, mechanical engineering. Four concepts were generated and decision matrixes were used to systematically select the best concept. By improving the process several benefits has been added to the process. More units are able to be tested and lead time is reduced. As the lead time is reduced the cost for each unit is reduced, workers will work less hours for the same amount of tested units, future work to further improve the process is also identified. The selected concept was concept 1, the sway stop concept. This concept is used to reduce the sway of the capacitors as they have entered the test facility, the box. By improving this part of the test process a time saving of 20 seconds per unit can be achieved, equivalent to 7% time reduction. This can be compared to an additional 1400 units each year.

Separating interface state response from parasitic effects in conductance measurements on organic metal-insulator-semiconductor capacitors

A simple model is developed for the admittance of a metal-insulator-semiconductor (MIS) capacitor which includes the effect of a guard ring surrounding the Ohmic contact to the semiconductor. The model predicts most of the features observed in a MIS capacitor fabricated using regioregular poly(3-hexylthiophene) as the active semiconductor and polysilsesquioxane as the gate insulator. In particular, it shows that when the capacitor is driven into accumulation, the parasitic transistor formed by the guard ring and Ohmic contact can give rise to an additional feature in the admittance-voltage plot that could be mistaken for interface states. When this artifact and underlying losses in the bulk semiconductor are accounted for, the remaining experimental feature, a peak in the loss-voltage plot when the capacitor is in depletion, is identified as an interface (or near interface) state of density of similar to 4 x 10(10) cm(-2) eV(-1). Application of the model shows that exposure of a vacuum-annealed device to laboratory air produces a rapid change in the doping density in the channel region of the parasitic transistor but only slow changes in the bulk semiconductor covered by the gold Ohmic contact. (C) 2008 American Institute of Physics.