Modular approach of a high current MOS compact model for circuit-level ESD simulation including transient gate-coupling behaviour

A novel modular strategy for highly flexible modeling of ESD-capable MOS compact models is introduced. This high current MOS model comprises the important gate-coupling effect and an approximated formulation for the avalanche multiplication factor. This enormously enhances the computation stability and performance of the model. An easy but accurate parameter extraction procedure based upon the model equations is described. Measurement and simulation of an application example employing the new ESD-model within a CMOS output driver exhibit the relevance of dynamic gate-coupling for the ESD-reliability of the circuit.     

Subthreshold behaviour of e.s.f.i.-s.o.s. transistors

Theoretical and experimental results are presented which illustrate the influence of various parameters on the subthreshold behaviour of e.s.f.i.-s.o.s. transistors. The numerical analysis accounts for the thin silicon film and the existence of a second interface. A comparison is made with a corresponding bulk transistor, furthermore, between a two- and a one-dimensional analysis of e.s.f.i.-s.o.s. m.o.s.t. The agreement for real cases is found to be excellent.     

IGBT negative gate capacitance and related instability effects

For high collector voltages, Insulated Gate Bipolar Transistors (IGBTs) exhibit a negative gate capacitance. In this condition, a p-channel inversion layer is formed on the N-base surface. The positive charges in the p-channel induce negative charges in the MOS gate electrode. This results in a negative gate capacitance. As a consequence of this negative capacitance, IGBT operation is inherently unstable, leading to current redistribution between cells or even chips     

New Organic Electrode Materials for Ultrafast Electrochemical Energy Storage

Organic materials are both environmentally and economically attractive as potential electrode candidates. This Research News reports on a new class of stable and electrically conductive organic electrodes based on metal porphyrins with functional groups that are capable of electrochemical polymerization, rendering the materials promising for electrochemical applications. Their structural flexibility and the unique highly conjugated macrocyclic structure allows the produced organic electrodes to act as both cathode and anode materials giving access to fast charging as well as high cycling stability. The extreme thermal and chemical stability of the porphyrin‐based organic electrodes and their chemical versatility suggest an important role for these molecular systems in the further development of novel electrochemical energy storage applications.     

Weighted Picture Automata and Weighted Logics

We investigate formal power series on pictures. These are functions that map pictures to elements of a semiring and provide an extension of two-dimensional languages to a quantitative setting. We establish a notion of a weighted MSO logics over pictures. The semantics of a weighted formula will be a picture series. We introduce weighted 2-dimensional on-line tessellation automata (W2OTA) and prove that for commutative semirings, the class of picture series defined by sentences of the weighted logics coincides with the family of picture series that are computable by W2OTA. Moreover, we show that the family of behaviors of W2OTA coincide precisely with the class of picture series characterized by weighted (quadrapolic) picture automata and consequently, the notion of weighted recognizability presented here is robust. However, the weighted structures can not be used to get better decidability properties than in the language case. For every commutative semiring, it is undecidable whether a given MSO formula has restricted structure or whether the semantics of a formula has empty support.     

Quantum device-simulation with the density-gradient model onunstructured grids

We describe an implementation of the density-gradient device equations which is simple and works in any dimension without imposing additional requirements on the mesh compared to classical simulations. It is therefore applicable to real-world device simulation with complex geometries. We use our implementation to determine the quantum mechanical effects for a MOS-diode, a MOSFET and a double-gated SOI MOSFET. The results are compared to those obtained by a 1D-Schrodinger-Poisson solver. We also investigate a simplified variant of the density-gradient term and show that, while it can reproduce terminal characteristics, it does not give the correct density distribution inside the device     

Schrifttumsberichte

Ohne Zusammenfassung     

Management decision support using long-term market simulation

In recent years Agent-based Computational Economics (ACE) has become an increasingly important method in market simulation. After liberalization of many former governmental owned or controlled industries the used operations research models are not longer sufficient to simulate market behavior due to individual action and increasing competition. Agent-based simulation appears to be an alternative approach considering also individual behavior and competition. Some short-term simulation approaches have shown promising results for the simulation in the domain of electricity markets. Picking up the desire for a long-term oriented simulation, this paper presents a basic agent-based model considering the investment decision within long-term planning of electricity markets. Additionally, regulatory agents are introduced as a third side in the market simulation to represent governmental decisions. This results in the definition of three types of agents representing electricity generating companies, consumers and governmental instances.     

Study of the oxidation protection of MgO-C refractories by means of boron carbide

Boron carbide is used as a highly effective antioxidant in carbon-containing refractories. The oxidation-inhibiting action of this additive has not been clearly defined. The work first deals in theory with the stability of boron carbide at high temperatures. The practical section presents the reaction sequence as determined by means of thermogravimetric analysis and X-ray diffraction analysis. The tests showed that B₄C oxidizes during firing at below 1000°C, to give magnesium borate (3 MgO · B₂O₃), which is stable at high temperatures.