Моделирование переходных процессов в полупроводниковых приборах на основе 4H-SiC (учет неполной ионизации легирующих примесей в модуле ATLAS программного пакета SILVACO TCAD)

Transient process in a resistor–capacitor (RC) circuit with a reverse-biased 4 H -SiC p – n diode as the capacitive element is simulated. Simulation is performed with the ATLAS software module from the SILVACO TCAD system for technology computer-aided design (TCAD). An alternative way, to that in ATLAS, to set the parameters of doping impurities partly ionized in 4 H -SiC at room temperature is suggested. (The INCOMPLETE physical model available in the ATLAS module, which describes the incomplete ionization of doping impurities in semiconductors, is unsuitable for simulating the dynamic characteristics of devices.) The simulation results are discussed in relation to previously obtained experimental results.

Soft Switching in Switched Inertance Hydraulic Circuits

Switched inertance hydraulic systems (SIHS) use inductive, capacitive, and switching elements to boost or “buck” (reduce) a pressure from a source to a load in an ideally lossless manner. Real SIHS circuits suffer a variety of energy losses, with throttling of flow during transitions of the high-speed valve resulting in as much as 44% of overall losses. These throttling energy losses can be mitigated by applying the analog of zero-voltage-switching, a soft switching strategy, adopted from power electronics. In the soft switching circuit, the flow that would otherwise be throttled across the transitioning valve is stored in a capacitive element and bypassed through check valves in parallel with the switching valves. To evaluate the effectiveness of soft switching in a boost converter SIHS, a lumped parameter model was constructed. Simulation demonstrates that soft switching improves the efficiency of the modeled circuit by 42% at peak load power and extends the power delivery capabilities by 77%.

Sensor Sticker for Detection of Fungi Spore Contamination on Bananas

Fungi growth on bananas during transportation not only results in loss of food but it also incurs considerable transport losses. To investigate the influence of spores on the development of fungi growth on the bananas we present a sensor sticker. The sticker can be put on the banana surface for the detection of spore concentration. The designed sensor comprises of a thin layer of culture medium (PDA agarose) coated on a capacitive sensor fabricated on a polyimide foil (5 μm). As spores germinate, the capacitance of the culture medium changes which is measured by the interdigital capacitive element that contains 2 electrodes (with 428 fingers) that have a length of 3 mm, a width and a gap of 7 μm. In addition to the culture medium one of the major requirements for the fungi to grow is air. As air cannot diffuse through the sticker, air cavities are integrated in the culture medium layer to provide the necessary amount of air for fungi growth. This method was successfully applied to determine different concentrations of Fusarium Oxysporum, a major fungi species responsible for banana contamination. Measured capacitance change after a fixed time interval depends on the initial concentration of spores. The measurement takes typically 6 hours.

Soft Switching in Switched Inertance Hydraulic Circuits

Switched Inertance Hydraulic Systems (SIHS) use inductive, capacitive, and switching elements to boost or buck a pressure from a source to a load in an ideally lossless manner. Real SIHS circuits suffer a variety of energy losses, with throttling of flow during transitions of the high-speed valve resulting in 44% of overall losses. These throttling energy losses can be mitigated by applying the analog of zero-voltage-switching, a soft switching strategy, adopted from power electronics. In the soft switching circuit, the flow that would otherwise be throttled across the transitioning valve is stored in a capacitive element and bypassed through check valves in parallel with the switching valves. To evaluate the effectiveness of soft switching in a boost converter SIHS, a lumped parameter model was constructed. The model demonstrates that soft switching can improve the efficiency of the circuit up to 42% and extend the power delivery capabilities of the circuit by 76%.

Radiation and Impedance Characteristics of a Circular Loop Antenna Driven by Fractional Order Electronics

Fractional calculus techniques (non-integer order systems) have been successfully applied in many fields of electronics and engineering. In this paper the effects of including fractional order electronic components on the radiated antenna pattern of a circular loop antenna is presented. A fractional order “RLC” impedance matching circuit is placed between the generator and the equivalent circuit of a loop antenna. The input impedance of the antenna and the antenna gain are controllable through varying the fractional orders of an inductive element and a capacitive element (Fractors) in the matching network. The circuit is presented and solved analytically, and some numerical simulations follow. We discuss the effects of fractional order components on the resulting radiation patterns. In particular, the amplitude of the antenna gain is controlled by the fractional order parameters. This effect could be exploited in future for antenna beam-forming applications when using an array of antenna elements. Further, the input impedance of the antenna circuit can also be controlled by the fractional order components. The introduction of fractional order variables provides for higher degrees of freedom, enabling a flexible approach to tuning antennas for optimal performance.

Dual-Mode Patch Filter with Metal Wall Structures

A dual-mode patch filter with metal wall structures is presented. The proposed structure consists of substrate 1 with metal wall structures and substrate 2 with a patch resonator. Because the symmetry of the structure can be perturbed by both long and short strips of the metal wall structures, the dual mode is achieved. The inductive element is introduced to the patch resonator through vias of the metal wall structures. The capacitive element is introduced through a gap between the patch resonator and the metal strips. The measured 3 dB fractional bandwidth for the passband is 10.4%, and the measured minimum insertion loss is 1.3 dB.

Electrical Response of Wet Chemically Grown ZnO Nanorods for Photovoltaic Application

ABSTRACTWet chemically prepared arrays of ZnO nanorods in electrolyte solution were investigated with respect to their capacitive behavior. The ZnO nanorod electrode could be well described by a frequency independent capacitive and a conductive element in parallel. The capacitive element is determined as space charge capacitance in the nanorods. However the dependency of the nanorod electrodes capacitance on the applied voltage bias is more complicated than for flat semiconductor electrodes.

Transient Response of the System Al/Al2O3/Electrolyte. Part II. A.c. Impedance Measurements During Steady-State Film Growth

Experiments are described in which the a.c. impedance of the system Al/Al2O3/electrolyte (glycol–borate) is measured under conditions of steady-state film growth. Using an equivalent circuit of a resistive and capacitive element in parallel, the results are presented in the form of the a.c. conductance, σac, and effective dielectric constant, Keff, of the oxide film as a function of the d.c. current density, I0, and angular frequency ω. The results show that σac/I0 and Keff vary with (ω/I0), but within experimental error are independent of ω and I0 separately. The dielectric relaxation model, assuming two ion-current-driven relaxation processes and using the constants determined in Part I, reproduces the data almost within experimental scatter. A poorer fit is achieved if only one relaxation process is assumed.