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Quantum Dots in Nanoelectronic Devices
Published in Sergey Edward Lyshevski, Nano and Molecular Electronics Handbook, 2018
Gregory L. Snider, Alexei O. Orlov, Craig S. Lent
The first step in implementing molecular QCA is to demonstrate external electric field-induced switching of an electron within a molecule. To accomplish this task, we have created an assembly of biased, vertically oriented two-dot cells sandwiched between two electrodes, and have measured the capacitance of the parallel plate device as a function of applied voltage across the plates. The schematic outline of the experiment is shown in Figure 8.13(a). The cells are covalently bound to a highly doped Si substrate in a monolayer film. In the active state, where there is a mobile electron within the molecule, the molecules are charged, and counter ions are incorporated in the film to compensate the charge. To avoid degradation of the two-dot cells, the top electrode is elemental Hg [22]. Mercury electrodes are versatile and cause little perturbation of the molecular layer. The capacitance is measured using a conventional high-frequency capacitance meter, consisting of a dc bias voltage in series with small-magnitude 1 MHz ac voltage.
Development of a scanning deep-level transient spectroscopy (SDLTS) system and application to well-characterised dislocations in silicon
Published in A G Cullis, P D Augustus, Microscopy of Semiconducting Materials, 1987, 2021
A schematic diagram of the SDLTS system developed at Oxford is given in Fig. 1 (D/A and A/D converters not shown). The DLTS part is conventional except that the sample is mounted inside an SEM and the capacitance meter is designed to give high sensitivity (Misrachi et al 1980). The SEM (Philips 505) is equipped with a LaB6 gun, an electrostatic beam-blanker and a cooling/heating specimen stage. The diodes used were Schottky barriers formed by evaporation of Au/Pd through a square mesh TEM specimen grid onto the prepared silicon slice. The mesh size was chosen to give individual diodes ∼ 500µm × ∼ 500µm, corresponding to a zero bias capacitance of ∼ 20pF (for Nd = 1015 cm−3). The back contact was formed by evaporating aluminium onto the oxide-free, saw-damaged back surface of the silicon slice. This contact is common to all the diodes on the slice. Electrical contact to any selected diode on the top surface was made by using a positionable gold-tipped probe located within the SEM. No post-annealing treatment was performed to reduce the resistance of the back contact because this might have modified the dislocations that were to be investigated. Consequently, the series resistance of the individual diodes is high (∼ 300ohm) and this limits the sensitivity of our resonant bridge which operates with a test voltage of 50mV at 1MHz. The capacitance meter has a sensitivity of ∼ 0·2pF/V with a 5mV noise level, corresponding to a capacitance noise of ∼ 1fF. The output of the boxcar integrator has a noise level corresponding to ∼ 0·3fF, and after digital signal processing in the controller the total system noise reduces to ∼ 0·12fF. This corresponds to a charge of ∼ 10–16C (∼ 750 electrons).
Enhancement of drying rate of moist porous media with dielectrophoresis mechanism
Published in Drying Technology, 2022
The dielectric constants of air and dry paper are 1 and 1.8, respectively. The dielectric constant of dry paper was measured with an in-house capacitance meter through a parallel-plate capacitor. The electric field distribution is shown in Figure 2. A strong non-uniform electric field was generated. Specifically, the region between neighboring electrodes experiences a lower electric field than that below the electrodes. Additionally, to determine the electric field strength variation along the y-direction between the DEP electrode and the ground electrode, four x locations (x = 0.0 mm, 1.0 mm, 1.3 mm, and 3.0 mm) were chosen, and x = 0.0 mm was defined as the center line in the DEP electrode slot, as shown in Figure 3. The change of along the y-axis at these locations is shown in Figure 4.
Design of Flexible Tactile Array Sensor
Published in IETE Journal of Research, 2021
Devika Kataria, Gustavo Sanchez, Jyoti Prakash Naidu, Mandayam A. Srinivasan
The sensitivity of the prototype TAS was measured using a calibrated capacitance meter (Sigma Instruments 4070 LCR meter). Force sensor A101 (Tekscan make Flexiforce, resistive type force sensor) was used to measure the force applied on TAS. The schematic diagram for the experimental setup is shown in Figure 10(a) where the area covered by the force weights was kept fixed as176.7 sq.mm. The capacitance between the TAS terminals and the resistance of the force transducer was measured simultaneously using LCR meter and multimeter to draw a plot of force applied and the change in mutual capacitance measured for the excited electrodes. Figure 10(b) shows the response from the prototype for various forces applied at the area of contact that was maintained constant. The figure shows that the TAS prototype is sensitive to the soft touch of 10 gms and has been tested for force up to 1.6 Kgs. The multi-axis graph shows that the resistance of the flexi force sensor reduced as we increased the force, and this has been verified with the performance graph in the force sensor datasheet [12].
Liquid Film Thickness in Vertical Circular Pipes Under Flooding Conditions at the Top End
Published in Nuclear Technology, 2020
Toshiya Takaki, Michio Murase, Koji Nishida, Raito Goda, Takeyuki Shimamura, Akio Tomiyama
Figure 7 shows that the measured pressure gradient dP/dz and the correlation for the wall friction factor fw gave good prediction of the void fraction α. However, there are few dP/dz data under flooding conditions. Table II lists the main experimental conditions for measuring dP/dz. Shimamura et al.9 measured α, which we have used in this section. The liquid Reynolds number was in the range of ReL = 230 to 2260 for the smooth film. Ilyukhin et al.10 did not measure α, and the measured dP/dz and Eqs. (2) and (20) were used to evaluate α in the range of ReL = 3120 to 11 300 for the smooth film. Bharathan et al.6 measured the liquid film thickness δ with a capacitance meter, dP/dz, and CCFL with the water level in the upper tank of h > 2D or h < D, and the increasing and decreasing processes of JG. No difference between the increasing and decreasing processes of JG (i.e., no hysteresis) was observed in the region of JL > 0. The CCFL characteristics differed between h > 2D and h < D, and data with h > 2D were used here. Uncertainty of the δ measurement was large. Therefore, we used the measured dP/dz and Eqs. (2) and (20) to evaluate α in the range of ReL = 160 to 4490. Data in the transition region may be included at low ReL of ReL = 160 to 4490 because it was difficult to classify the smooth film and the transition from dP/dz.