Sub-threshold characteristics of the dual material gate 4H-SiC MESFET (DMGFET) are investigated and the analytical models to describe the drain-induced barrier lowering (DIBL) effect are derived by solving one- and two-dimensional Poisson's equations. Using these models, we calculate the bottom potential of the channel and the threshold voltage shift, which characterize the drain-induced barrier lowering (DIBL) effect. The calculated results reveal that the dual material gate (DMG) structure alleviates the deterioration of the threshold voltage and thus suppresses the DIBL effect due to the introduced step function, which originates from the work function difference of the two gate materials when compared with the conventional single material gate metal—semiconductor field-effect transistor (SMGFET).
In this article, laterally diffused MOS (LDMOS) combined with flexible substrate polydimethylsiloxane (PDMS) which can be used in flexible electronic system is described. The flexible substrate has insulation characteristics, which makes the original substrate float; thus, the substrate electrode and reduce surface electric field (RESURF) technology are missing. The simulation results show that the breakdown voltage (BV) of LDMOS combined with PDMS decreases by 23.3%. Considering that most flexible electronic systems require thin functional layers to achieve portability, the use of SOI LDMOS can achieve better performance on thinner substrates. Then, through simulation, the flexible substrate will reduce the BV of the SOI LDMOS by 17.4%, and combined with experiments and tests, it is verified that the flexible substrate will indeed reduce the BV of the SOI LDMOS by 15%, which is basically consistent with the simulation results. But there is no obvious effect on the specific ON-resistance ( R ON,sp ). For the phenomenon of substrate floating, a new structure named surface electrodes trench drift region SOI LDMOS (SETD SOI LDMOS) is proposed. After optimizing the simulation, compared with conventional SOI LDMOS, the SOI LDMOS combined with the flexible substrate can achieve a 57.54% increase in the BV while reducing R ON,sp by 11%.
A novel structure of 4H-SiC MESFETs is proposed that focuses on surface trap suppression. Characteristics of the device have been investigated based on physical models for material properties and improved trap models. By comparing with the performance of the well-utilized buried-gate incorporated with a field-plate (BG-FP) structure, it is shown that the proposed structure improves device properties in comprehensive aspects. A p-type spacer layer introduced in the channel layer suppresses the surface trap effect and reduces the gate-drain capacitance (Cgd) under a large drain voltage. A p-type spacer layer incorporated with a field-plate improves the electric field distribution on the gate edge while the spacer layer induces less Cgd than a conventional FP. For microwave applications, 4H-SiC MESFET for the proposed structure has a larger gate-lag ratio in the saturation region due to better surface trap isolation from the conductive channel. For high power applications, the proposed structure is able to endure higher operating voltage as well. The maximum saturation current density of 460 mA/mm is yielded. Also, the gate-lag ratio under a drain voltage of 20 V is close to 90%. In addition, 5% and 17.8% improvements in fT and fmax are obtained compared with a BG-FP MESFET in AC simulation, respectively. Parameters and dimensions of the proposed structure are optimized to make the best of the device for microwave applications and to provide a reference for device design.
With the rapid development of the traditional inorganic semiconductor industry, the improvement of its electrical performance is gradually approaching to the limit. It is difficult to continue to improve the performance, lessen the size, and reduce the cost. Therefore, organic semiconductor materials and devices with simple process and low cost have been found and gradually become a new research hotspot. Although organic semiconductor materials and devices are developing rapidly, their electrical properties, such as carrier mobility, are considerably inferior to those of inorganic semiconductors, and their research direction and application prospect are relatively fixed and single. They are developed only in display, sensing, photoelectric conversion and other fields, but the researches on switching power devices, integrated circuits and other fields are still relatively blank. At the same time, power devices are used only in the field of inorganic semiconductors. Therefore, in order to expand the research direction of organic semiconductors and power devices at the same time, a novelsilicon on insulator lateral double-diffused metal oxide semiconductor (SOI LDMOS)power device is reported in this paper. Unlike the SOI LDMOS power devices in traditional inorganic semiconductors, this novel device can be used in the field of organic semiconductors by combining with insulated flexible substrates, which provides a new possibility for the research direction of organic semiconductors. In this paper, both simulation and experiment verify that specific on-resistance (<i>R</i><sub>ON,sp</sub>) and threshold voltage (<i>V</i><sub>TH</sub>) do not change significantly when the conventional SOI LDMOS lacks the substrate electrode, but the breakdown voltage decreases by about 15% due to the absence of the substrate electrode or the longitudinal electric field. In response to this phenomenon, in this paper proposed is a novel SOI LDMOS power device that possesses surface substrate electrodes and drift zone oxide trenches. This novel device can provide electrodes for the substrate again, optimize the horizontal and vertical electric field, and significantly change neither of the <i>R</i><sub>ON,sp</sub> and the <i>V</i><sub>TH</sub>. At the same time, the breakdown voltage (BV) of conventional SOI LDMOS is increased by 57.54%, which alleviates the adverse effects caused by the application in the field of organic semiconductors. This novel SOI LDMOS power device provides the possibility of applying traditional power semiconductors to the research of organic semiconductors, and has innovative significance for expanding the organic semiconductor research.
For hybrid energy storage systems in DC microgrids, a droop control consisting of virtual capacitors and virtual resistors can decompose power into high-frequency components and low-frequency components, then assign them to batteries and supercapacitors to respond respectively. However, aiming at the service life of the energy storage system, this paper considers the characteristics and key parameters of the hybrid energy storage structure and proposes an adaptive drooping comprehensive control strategy considering the SOC of the energy storage unit given the shortcomings of power distribution within the current hybrid energy storage. According to the self-regulation capacity of each energy storage unit, it is sorted and constrained, and protected by using SOC, which ensures the economy and safety of the system while ensuring power distribution. The traditional droop control and adaptive droop control are simulated to verify the effectiveness of the proposed control strategy.
The actual situation of carbon-emission reduction in China’s power sector has not yet achieved the expected benefits. The rent-seeking behavior of participants in power construction projects (PCPs) hinders the realization of low-carbon benefits. It is necessary to explore the behavioral strategies of the various participants in the low-carbon transition of PCPs. This paper creatively constructs an evolutionary game model of PCPs’ participants from the perspective of MRV (monitoring, reporting, and verification) and introduces the influence of the public to provide a comprehensive analysis of strategic equilibrium points. Through numerical simulations with MATLAB R2021a software, this paper explores the strategic choices of participants in different situations and gives relevant inferences and proofs. The results show that the grid company dominates at the initial stage and promotes participants to regulate behaviors. Under the premise of satisfying the system-stability requirements, setting the growth rate of the grid company’s punishments to 100% can enhance the willingness for strict supervision, while the growth rate of the supervision costs to 200% significantly decreases the probability of strict supervision. With the integration of MRV and PCPs, participants spontaneously fulfill the carbon-emission-reduction tasks. Reasonable control of input costs can effectively avoid the occurrence of rent-seeking behavior. In addition, this paper sets the public-influence growth rate at 200% and finds that the public plays a greater role in driving participants to fulfill responsibilities. Based on the results, a low-carbon transition mechanism for PCPs under the MRV system is proposed by considering several dimensions, which provides suggestions for participants to fulfill carbon-reduction responsibilities.
A two-dimensional model of a 4H-SiC metal—semiconductor—metal (MSM) ultraviolet photodetector has been established using a self-consistent numerical calculation method. The structure-dependent spectral response of a 4H-SiC MSM detector is calculated by solving Poisson's equation, the current continuity equation and the current density equation. The calculated results are verified with experimental data. With consideration of the reflection and absorption on the metal contacts, a detailed study involving various electrode heights (H), spacings (S) and widths (W) reveals conclusive results in device design. The mechanisms responsible for variations of responsivity with those parameters are analyzed. The findings show that responsivity is inversely proportional to electrode height and is enhanced with an increase of electrode spacing and width. In addition, the ultraviolet (UV)-to-visible rejection ratio is > 103. By optimizing the device structure at 10 V bias, a responsivity as high as 180.056 mA/W, a comparable quantum efficiency of 77.93% and a maximum UV-to-visible rejection ratio of 1875 are achieved with a detector size of H = 50 nm, S = 9 μm and W = 3 μm.
The digital twin workshop is the basic unit for realizing smart manufacturing. Its model is the prerequisite for applying digital twins in workshops. Geometric model assembly is the primary concern in workshop-level digital twin modeling. However, current research lacks sufficient focus on the efficiency and application modes of equipment mesh model assembly features in geometric model assembly, hindering the construction of the workshop-level digital twin model. The equipment-level digital twin model typically only contains assembly information between individual parts and is generally represented by polygonal meshes; the lack of assembly information between equipment models impedes the assembly of the workshop-level digital twin model. To improve the efficiency of workshop-level digital twin modeling and the reusability of the original 3D assembly information, this paper proposes an assembly feature construction method of equipment mesh model for digital twin workshops. A 3D assembly information model is constructed to describe the information related to the equipment geometric model and the assembly features. Then, the assembly features of the equipment mesh model are gradually positioned preliminarily and precisely, achieving precise mapping of the assembly features in the 3D information model to the equipment mesh model and efficient construction of equipment mesh model assembly features. Finally, with the construction and application of equipment mesh model assembly features in an arc welding workshop and storage workshop as an example, the feasibility of the method in improving the modeling efficiency is verified through relevant comparative experiments.
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