This paper addresses the influences of device and circuit mismatches on paralleling the Silicon Carbide (SiC) MOSFETs. Comprehensive theoretical analysis and experimental validation from paralleled discrete devices to paralleled dies in multichip power modules are first presented. Then, the influence of circuit mismatch on paralleling SiC MOSFETs is investigated and experimentally evaluated for the first time. It is found that the mismatch of the switching loop stray inductance can also lead to on-state current unbalance with inductive output current, in addition to the on-state resistance of the device. It further reveals that circuit mismatches and a current coupling among the paralleled dies exist in a SiC MOSFET multichip power module, which is critical for the transient current distribution in the power module. Thus, a power module layout with an auxiliary source connection is developed to reduce such a coupling effect. Lastly, simulations and experimental tests are carried out to validate the analysis and effectiveness of the developed layout.
This paper investigates the improved photo-current response obtained by depositing Al nanoparticles on top of a Si diode. Well defined Al nanodiscs with a diameter and height of 100 nm are produced on the surface of a Si diode using electron-beam lithography, and the change in photo-current generation is characterized. A blue shift of the photo-current response is demonstrated, substantially improving the relation between gains and losses compared to what is typically observed in similar schemes using Ag nanoparticles. Enhanced photo-current response is observed in diodes with Al particles on the surface at all wavelengths larger than ≈465 nm, thereby minimizing the losses in the blue range usually reported with Ag nanoparticles on the surface.
This paper proposes a general physics-based model for identifying the parasitic capacitance in medium-voltage (MV) filter inductors, which can provide analytical calculations without using empirical equations and is not restricted by the geometrical structures of inductors. The elementary capacitances of the MV inductor are identified, then the equivalent capacitances between the two terminals of the inductor are derived under different voltage potential on the core. Further, a three-terminal equivalent circuit, instead of the conventional two-terminal equivalent circuit, is proposed by using the derived capacitances. Thus, the parasitic equivalent capacitance between the terminals and core are explicitly quantified. Experimental measurements for parasitic capacitances show a good agreement with the theoretical calculations. Index terms-Physics-based modeling, parasitic capacitance, medium-voltage, filter inductors, three-terminal equivalent circuit.This work is supported by MV-BASIC project (https://www.mvbasic.et.aau.dk/), which is co-funded by the
New packaging solutions and power module structures are required to fully utilize the benefits of emerging commercially available wide bandgap semiconductor devices. Conventional packaging solutions for power levels of a few kilowatt are bulky, meaning important gate driver and measurement circuitry are not properly integrated. This paper presents a fast-switching integrated power module based on gallium nitride enhancementmode high-electron-mobility transistors, which is easier to manufacture compared with other hybrid structures. The structure of the proposed power module is presented, and the design of its gate driver circuit and board layout structure is discussed. The thermal characteristics of the designed power module are evaluated using COMSOL Multiphysics. An ANSYS Q3D Extractor is used to extract the parasitics of the designed power module, and is included in simulation models of various complexities. The simulation model includes the SPICE model of the gallium nitride devices, and parasitics of components are included by experimentally characterizing them up to 2 GHz. Finally, the designed power module is tested experimentally, and its switching characteristics cohere with the results of the simulation model. The experimental results show a maximum achieved switching transient of 64 V/ns and verify the power loop inductance of 2.65 nH.
This paper presents a novel method for the self-assembly of aluminum nanoparticles on Si and fused silica. Due to high reactivity with oxygen, ex-vacuo annealing of thin deposited metal films, a method used extensively with other metals, does not work with aluminum. In the present experiment this problem was overcome by annealing the samples in-vacuo in the deposition chamber. Aluminum was thermally evaporated onto substrates at elevated temperatures (200-400 ° C) and annealed for 60 min without breaking the vacuum. It is shown that at 300 and 400 ° C the average particle size can be controlled by adjusting the amount of evaporated aluminum. Particle diameters ranging from 20 to 130 nm are demonstrated. These particles support localized surface plasmon resonances, a property that can be utilized for enhancing the efficiency of thin Si solar cells. This is explored here, and an increase in external quantum efficiency of up to 15% in a thin-film Si solar cell is demonstrated.
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