Development of ring-shaped electrostatic coupled capacitance sensor for the parameter measurement of gas-solid flow

This paper develops a novel non-intrusive ring-shaped electrostatic coupled capacitance sensor (ECCS) for the parameter measurement of gas-solid flow to eliminate the temperature drift of traditional capacitance sensor and to improve the reliability of velocity measurement. In ECCS, one source electrode and two detection electrodes are housed in a sensing head to simultaneously derive two pairs of capacitance and electrostatic signals, which can achieve the simultaneous measurement of the particle velocity, concentration and mass flow rate within the same sensing space of gas-solid flow system. The effects of the isolation electrodes on the capacitance sensitivity and the temperature drift of the sensor standing capacitance are further investigated. Then, a weighted velocity is determined by fusing the capacitance correlation velocity and the electrostatic correlation velocity based on the correlation coefficients, which are useful for the reliable measurement of gas-solid flow. Finally, experiments are carried out to test the performance of the developed ring-shaped ECCS. Results demonstrate that the developed ECCS triples the capacitance sensitivity for the radial position from -15 mm ∼15 mm. The temperature drift of the capacitance signal is less than 0.075 mV/oC from the room temperature to 65 oC, and thus the sensor standing capacitance is almost impervious to the temperature. After calibrating the relationship between the particle concentration and the capacitance signal, the developed ECCS can measure the particle mass flow rate with a relative error less than ±8%.

Mechanism and Reduction of Interlayer Peeling Defect in IGZO TFTs Formation

32in full high definition display devices based on back-channel etch IGZO TFTs were prepared. The mechanism of interlayer peeling defect in IGZO TFTs formation was studied. It turns out that the passivation layer was peeling with the underlying source electrode, which caused an interruption in signal transmission. Relevant process improvements were implemented, and the interlayer peeling defect in IGZO TFTs was solved.

An Optimized Structure of Split-Gate Resurf Stepped Oxide UMOSFET

In this paper, a split-gate resurf stepped oxide with double floating electrodes (DFSGRSO) U-shape metal oxide semiconductor field-effect transistor (UMOSFET) is proposed. The floating electrodes are symmetrically distributed on both sides of the source electrode in the trench. The performance of the DFSGRSO UMOSFET with different size of floating electrodes is simulated and analyzed. The simulation results reveal that the floating electrodes can modulate the distribution of the electric field in the drift area, improving the performance of the device significantly. The breakdown voltage (BV) and figure of merit (FOM) of the DFSGRSO UMOSFET at optimal parameters are 23.6% and 53.1% higher than that of the conventional structure. In addition, the regulatory mechanism of the floating electrodes is analyzed. The electric field moves from the bottom of the trench to the middle of the drift area, which brings a new electric field peak. Therefore, the distribution of the electric field is more uniform for the DFSGRSO UMOSFET compared with the conventional structure.

Solution-Processable Vertical Organic Light-Emitting Transistors (VOLETs) with Directly Deposited Silver Nanowires Intermediate Source Electrode

A simple spin-coating process for fabricating vertical organic light-emitting transistors (VOLETs) is realized by utilizing silver nanowire (AgNW) as a source electrode. The optical, electrical and morphological properties of the AgNW formation was initially optimized, prior VOFET fabrication. A high molecular weight of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] MEH-PPV was used as an organic semiconductor layer in the VOFET in forming a multilayer structure by solution process. It was found that current density and luminance intensity of the VOLET can be modulated by a small magnitude of gate voltage. The modulation process was induced by changing an injection barrier via gate voltage bias. A space-charge-limited current (SCLC) approach in determining transistor mobility has been introduced. This preliminary and fundamental work is beneficial towards all-solution processing display devices.

Numerical Modeling of an Organic Electrochemical Transistor

We develop a numerical model for the current-voltage characteristics of organic electrochemical transistors (OECTs) based on steady-state Poisson’s, Nernst’s and Nernst–Planck’s equations. The model starts with the doping–dedoping process depicted as a moving front, when the process at the electrolyte–polymer interface and gradually moves across the film. When the polymer reaches its final state, the electrical potential and charge density profiles largely depend on the way the cations behave during the process. One case is when cations are trapped at the polymer site where dedoping occurs. In this case, the moving front stops at a point that depends on the applied voltage; the higher the voltage, the closer the stopping point to the source electrode. Alternatively, when the cations are assumed to move freely in the polymer, the moving front eventually reaches the source electrode in all cases. In this second case, cations tend to accumulate near the source electrode, and most of the polymer is uniformly doped. The variation of the conductivity of the polymer film is then calculated by integrating the density of holes all over the film. Output and transfer curves of the OECT are obtained by integrating the gate voltage-dependent conductivity from source to drain.

Role of Trench Bottom Shielding Region on Switching Characteristics of 4H-SiC Double-Trench Mosfets

The effect of a gate trench bottom p+region (BPR) on the dynamic characteristics of 4H-SiC double-trench MOSFETs was investigated. Although employing a BPR led to an improved trade-off in the static characteristics, a BPR adversely affected the switching characteristics in spite of a reduction in the Miller capacitance compared to the case without a BPR.Simulation analysis revealed that a resistance between a BPR and a source electrode led to an increase in the switching loss. We have found reduction of the resistance is insufficient in order to provide benefits from the BPR. Hence, it is necessary to improve layouts of contacts of the BPR to the source electrode.