An Extra Electrostatic Energy in Semiconductors and its Impact in Nanostructures

This work revisits the classical concept of electric energy and suggests that the common definition is likely to generate large errors when dealing with nanostructures. For instance, deriving the electrostatic energy in semiconductors using the traditional formula fails at giving the correct electrostatic force between capacitor plates and reveals the existence of an extra contribution to the standard electrostatic energy. This additional energy is found to proceed from the generation of space charge regions which are predicted when combining electrostatics laws with semiconductor statistics, such as for accumulation and inversion layers. On the contrary, no such energy exists when relying on electrostatics only, as for instance when adopting the so-called full depletion approximation. The same holds for charged or neutral insulators that are still consistent with the customary definition, but which are in fact singular cases. In semiconductors, this additional free energy can largely exceed the energy gained by the dipoles, thus becoming the dominant term. Consequently, erroneous electrostatic forces in nanostructure systems such as for MEMS and NEMS as well as incorrect energy calculations are expected using the standard definition. This unexpected result clearly asks for a generalization of electrostatic energy in matter in order to reconcile basic concepts and to prevent flawed force evaluation in nanostructures with electrical charges.Comment: 24 pages 8 figure

Offset Drift Dependence of Hall Cells with their Designed Geometry

In this paper, the performance of CMOS Hall Effect Sensors with four different geometries has been experimentally studied. Using a characteristic measurement system, the cells residual offset and its temperature behavior were determined. The offset, offset drift and sensitivity are quantities that were computed to determine the sensors performance. The temperature coefficient of specific parameters such as individual, residual offset and resistance has been also investigated. Therefore the optimum cell to fit the best in the performance specifications was identified. The variety of tested shapes ensures a good analysis on how the sensors performance changes with geometry

Measurement and Performance Evaluation of a Silicon On Insulator Pixel Matrix

A new technique for driving silicon-on-insulator pixel matrixes has been proposed in [1], which was based on transient charge pumping for evacuating the extra photogenerated charges from the body of the transistor. An 8x8 pixel matrix was designed and fabricated using the above technique. In this paper, the measurement set-up is described and the performance evaluation procedure is given, together with results of its implementation on the fabricated pixel matrix. The results show the applicability of the charge pumping technique and the effective operation of the image sensor

Accounting for Quantum Effects and Polysilicon Depletion in an Analytical Design-Oriented MOSFET Model

Abstract An analytical MOSFET model is presented that accounts for energy quantization in inversion charge and depletion in the poly gate. The model consistently describes effects on charges, transcapacitances, drain current and transconductances in all regions of operation, depending on five physical device parameters and bias conditions. Comparison to experimental data is provided and parameter extraction briefly discussed. The model offers manageable equations providing insight into the physical phenomena, thereby supporting analog circuit design practice as well as efficient circuit simulation

Modeling methodology of high-voltage substrate minority and majority carrier injections

This paper presents a modeling methodology for substrate current coupling mechanisms. An enhanced model of the diode ensuring continuity of minority carriers is used to build an equivalent schematic, accounting for minority and majority carrier propagation in the substrate. For the first time a typical H-bridge structure is simulated with the proposed methodology. The parasitic current injected in the substrate by a high-voltage structure is simulated in a circuit-level simulator as well as with a finite elements method. Both are compared to measurements and show a very good agreement. The simulation resources needed by the proposed equivalent schematics are thus greatly reduced in regard to the finite element approach, offering an efficient tool for substrate modeling in smart power IC's

A Circuit Model for CMOS Hall Cells Performance Evaluation including Temperature Effects

In order to provide the information on their Hall voltage, sensitivity, and drift with temperature, a new simpler lumped circuit model for the evaluation of various Hall cells has been developed. In this sense, the finite element model proposed by the authors in this paper contains both geometrical parameters (dimensions of the cells) and physical parameters such as the mobility, conductivity, Hall factor, carrier concentration, and the temperature influence on them. Therefore, a scalable finite element model in Cadence, for behavior simulation in circuit environment of CMOS Hall effect devices, with different shapes and technologies assessing their performance, has been elaborated.Peer Reviewe

Temperature considerations on Hall Effect sensors current-related sensitivity behaviour

The present paper focuses on evaluating the temperature effects on Hall Effect sensors sensitivity behavior. To this purpose, an analysis of the factors affecting the sensors current-related sensitivity is performed, consisting of several pertinent considerations. An analytical investigation of the carrier concentration temperature dependence including the freeze-out effect influence was performed. This information was subsequently included in accurate prediction of the current-related sensitivity temperature behavior. For a specific CMOS integration process of the Hall sensors, a parabolic curve is obtained for the relative variation of the current-related sensitivit

Temperature considerations on Hall Effect sensors current-related sensitivity behaviour

The present paper focuses on evaluating the temperature effects on Hall Effect sensors sensitivity behavior. To this purpose, an analysis of the factors affecting the sensors current-related sensitivity is performed, consisting of several pertinent considerations. An analytical investigation of the carrier concentration temperature dependence including the freeze-out effect influence was performed. This information was subsequently included in accurate prediction of the current-related sensitivity temperature behavior. For a specific CMOS integration process of the Hall sensors, a parabolic curve is obtained for the relative variation of the current-related sensitivity

Mobility Measurement in Nanowires Based on Magnetic Field-Induced Current Splitting Method in H-Shape Devices

This work investigates a new method to measure mobility in nanowires. Based on a simple analytical approach and numerical simulations, we bring evidence that the traditional technique of Hall voltage measurement in low dimensional structures such as nanowires may generate large errors, while being challenging from a technological aspect. Here, we propose to extract the drift mobility in nanowires by measuring a variation of the electric current due to the presence of a magnetic field, in a specific nanowire network topology. This method overcomes the limitations inherent to the standard Hall effect technique and might open the way to a more precise and simple measurement of mobility in nanowires, still a matter of intensive research

A viscosity-dependent affinity sensor for continuous monitoring of glucose in biological fluids

We present a viscometric affinity biosensor for continuous monitoring of glucose in biological fluids such as blood and plasma. The sensing principle of this chemico-mechanical sensor is based upon the viscosity variation of a sensitive fluid with glucose concentration. Basically, this device includes both an actuating and a sensing piezoelectric diaphragms as well as a flow-resistive microchannel. In order to confine the sensitive fluid and allow glucose diffusion into the sensor, a free-standing alumina nanoporous membrane is also used as size-selective interface. Measurements carried out at nominal temperatures of 25 and 37°C reveal that this sensor topology exhibits a high resolution in the current range of physiological blood glucose concentrations, i.e. 2-20 mM. In addition, complete reversibility was also demonstrated for at least 3 days. Finally, measurements performed in human blood serum confirm that this sensor fulfils all basic requirements for a use in continuous glucose monitoring of biological fluids