Papers by Keyword: Contact Resistance

Abstract: For what is believed to be for the first time, the device physics based modeling approach to derive the generic model current equations of organic thin film transistor (OTFT) is described. Firstly, the current model equation is derived by considering the dependence of mobility on gate voltage and doping density, which is more realistic and relevant to organic materials containing TFTs. To model small molecule or polymer TFT, the potential drop across contacts is taken into account as contacts are not ohmic due to some morphological disorders. Further the effect of contact resistance is included and accordingly the generic model current equation is modified. It shows a good agreement of proposed current equation with simulated results which validates the proposed OTFT model from ohmic to saturation regime. Moreover, the analytical model is used to extract the contact and channel resistances in linear and saturation region and these resistances are verified through potential cut line (PCL) and transmission line methods (TLM). The extracted parameters are not only used to verify the electrical characteristics but also exhibit insight on contact potential, charge injection and transport phenomenon for organic TFT operation.

Abstract: The bad shunting of track circuit results from the contact resistance between wheel and rail and its solution becomes a disturbing problem for electrical engineer technicians. Based on the Holm electrical contact model, Greenwood model and thermal breakdown theory, this paper analyzed the mechanism of contact resistance between wheel and rail. Then breakdown characteristic of the imperfect electrical layer is analyzed. Through field test, its character is similar to reversed breakdown of diode and the contact resistance decreases as the current ascending. The conclusions of the experiments not only prove the validity of Holm and Greenwood model, but also provide the professional and practical parameters for solving bad shunting. And these parameters involve the breakdown voltage and short-circuit current.

Abstract: This work presents a polymer based force-fit interconnection module (Click-Bond) that can be used to establish reliable electrical and mechanical interconnections between electronic components and textile circuit boards at room temperature. It is an extremely fast and cost-efficient process that is able to bring smart textile applications into the mass market. The semi-crystalline polymer POM-C is selected as material. It has good physical properties and can be used in injection molding. After the design is made mechanical experiments are performed to analyze the maximum forces and stress relaxation of the modules. Additionally, the compressibility of fabrics is analyzed to be able to design the module to apply a certain pressure. Finally, a multi-terminal board is presented that allows to easily integrate more complex electronics boards into smart textiles.

Abstract: The aim of the paper is to present the possibilities of computational simulations for the casting of aluminum matrix composite (AlMMC) reinforced with ceramics based on experimental data. The comparison of simulation and experimental results concerned the solidification process i.e. the course of solidification, temperature distribution and final arrangement of reinforcement particles. First, we have performed the experimental gravity casting of the aluminum matrix alloy AK12 (AlSi12CuNiMg2) and the composites AK12/SiC and AK12/C_g reinforced with silicon carbide SiC and glass carbon Cg, respectively, into the sand mold. During the experiment we have recorded the temperature using the ThermaCAM photometer system as well as in the selected point inside the sand mold. Using experimental data we have carried out the numerical calculations according to the methods and procedures contained in the program ANSYS Fluent 13. We have based the simulations on the two-dimensional model in which the Volume of Fluid (VOF) and enthalpy methods have been applied. The former is to describe two-phase system (air-composite matrix free surface, volume fraction of particular continuous phase) and the latter shows modeling of the solidification process of the alloy and composite matrix. We have used the Discrete Phase Model (DPM) to depict the presence of reinforcement particles. The assumption of the appropriate values of simulation parameters has shown that the simulation results are convergent with experimental ones. We have observed a similar course of the composite solidification (temperature change at the designated point), the temperature distribution and the arrangement of reinforcement particles for the simulation and experiment.

Abstract: In this work the electrical properties of Ni and Ni₂Si contacts on n-type 4H-SiC were correlated to the strong structural changes at the contact/SiC interface upon annealing. We can conclude that only δ-Ni₂Si grains play a main role in determining electrical transport properties of the Ni-based ohmic contacts to n-SiC. It is presumed that a recrystallization and texturization of δ-Ni₂Si phase on (0001)SiC-surface during high temperature annealing (> 900°C) contributes to the change of barrier heights, as well as specific contact resistance of contacts.

Abstract: The channel mobility in 3C-SiC n-MOSFETs is investigated by current-voltage and Hall-effect measurements. For comparison, these techniques are also applied to 3C-SiC bulk rods. It turns out that the channel mobility depends on the orientation of the crystal and channel length. The observed results are traced back to the influence of Si-terminated stacking faults (Si-SFs), to the resistance of the drain/source contact and to the warping of the wafer caused by the special growth technique.

Abstract: This paper introduces a way to characterize corrosion using contact resistance and points out the noticed problems during the test process. By characterize the corrosion degree using electrical contact resistance, surface morphology and contact pressure should be proper to the metal contacted. It is quantitative to investigate the anticorrosion performance of the oil and paste smear layer and corrosiveness of gas environment and liquid environment.

Abstract: Fabric keyboard is a field of smart textile. It can overcome many disadvantages of conventional keyboard. In order to study the fabric keyboard switch, trapezia structures of two kinds of orifice dimension are designed for example 8 wefts and 16 wefts. Different roots of conductive wires are woven into the down layer of the orifice part for each kind of orifice dimension. 4 and 8 roots of wires are woven for 8 wefts. 4, 8 and 16 roots of wires are woven for 16wefts. Then the immediate regain, connection pressure, connection ratio and contact resistance are tested and analyzed for every kind of fabric keyboard switch. It is concluded that 8 wefts orifice dimension and 8 roots of wires woven into the down layer of the orifice part is a better project. These findings may assist in recommendations regarding the further development of flexible fabric keyboard.

Abstract: Instead of selective emitter technology we investigate an alternative way to optimize contact formation and increased blue responsivity of highly resistive emitter solar cells using screen print technology for the deposition of the frontside metallization grid. We show with the aid of an inline doping/diffusion set-up at Blue Chip Energy that tuning the emitter doping profile is an alternative way to reduce the effect of Auger recombination in the spectral range from 300 nm to 600 nm. By properly choosing the process conditions we were able to minimize the detrimental effect of the low surface concentration of the dopant on the contact resistance. Due to improved blue light responsivity a significant gain in short circuit current Jsc was achieved. This and a reduced reverse saturation current I00E yielded a higher open circuit voltage VOC and an increase of cell efficiency from 17.6 %-avg to more than 17.9 %-avg.

Abstract: The impact of implantation temperature and dose as well as the annealing process with and without a graphite capping layer on surface roughness, carrier mobility and specific contact resistance are investigated and compared. The use of the capping layer is proven to be particularly advantageous: (1) a deterioration of surface roughness can be avoided even for high dose implantations and (2) the specific contact resistance is reduced. Furthermore, it is shown that a capping layer prevents surface contamination during annealing.