A lateral superjunction SOI LDMOS with double‑conductive channels

Weizhong Chen,Haifeng Qin,Xuwei Lin,Yi Huang,Zhengsheng Han 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.4

A novel lateral superjunction silicon-on-insulator lateral double-diffused MOS with double-conductive channels (DCLDMOS) is proposed and subsequently investigated by the SENTAURUS TCAD. First, the double channels (DC) feature a surface and bulk gate for providing the surface and bulk electron channels, respectively. Second, the P-pillar is inserted into the N-drift to divide it into the N-drift1 and N-drift2 regions. In this manner, the lateral super junction (SJ) can be formed by the sandwich-structured N-drift1/P-pillar/N-drift2. At the forward conduction state, the DC provides the double electron emission channels. The specific on-resistance (Ron,sp) is obviously decreased, and an even higher peak transfer conductance (gm) is achieved. At the breakdown state, the SJ helps to deplete the whole drift, including the N-drift1/P-pillar/N-drift2, and the electric field Efield distribution is effectively optimized. Furthermore, the Ron,sp is significantly decreased by the DC and SJ. Consequently, the tradeoff relationship between BV and Ron,sp is improved by the charge compensation and the assisted depletion effect, which are performed by the SJ. The results indicate that the DC LDMOS can break through the single RESURF and achieve Baliga’s figure of merit (FOM) of 3.32 MW/cm2. In addition, the DC LDMOS with the N-trench (NT) inserted into the buried oxide (DC-NT LDMOS) can achieve better breakdown properties by further optimizing the Efield distribution between the source and drain regions, and BV is remarkably increased. Furthermore, Ron,sp can be decreased by the NT. Finally, it breaks through the triple RESURF to achieve the FOM of 4.87 MW/cm2.

A snapback‑free reverse‑conducting IGBT with multiple extraction channels

Weizhong Chen,Xuwei Lin,Shun Li,Yao Huang,Yi Huang,Zhengsheng Han 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.2

A novel Reverse-Conducting Insulated Gate Bipolar Transistor (RC-IGBT) with Multiple Extraction Channels (MEC) is proposed and investigated. The MEC is characterized by two transistors NPN1 (Nbuffer/Pbarrier/Ncollector), NPN2 (Nbuffer/Pfloat/Npoly) and short Rgap in the collector. The P-Collector, N-Collector, polysilicon and Rgap are shorted together, thus the NPN1, NPN2 and Rgap are parallel with the PNP transistor (Pbody/Nbuffer/Pcollector). At the forward conduction, the unipolar mode is effectively suppressed by the electron barriers P-barrier (the base of the NPN1) and P-float (the base of the NPN2), thus the snapback effect can be completely eliminated. At the turn-off, the electrons are quickly extracted by three channels of the NPN1, NPN2 and Rgap, thus the Eoff can be remarkably decreased. Results show at the same Von of 2.8 V, the Eoff of the MEC RC-IGBT is reduced by 20%, 37%, 45% and 59% compared to AB, FPL, DFS and TOC RC-IGBT, respectively. Therefore the excellent trade-off characteristics with snapback free are achieved.

Molecular Dynamics Investigation of the Effects of Concentration on Hydrogen Bonding in Aqueous Solutions of Methanol, Ethylene Glycol and Glycerol

Ning Zhang,Weizhong Li,Cong Chen,Jianguo Zuo,Lindong Weng 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.9

Hydrogen bonding interaction between alcohols and water molecules is an important characteristic in the aqueous solutions of alcohols. In this paper, a series of molecular dynamics simulations have been performed to investigate the aqueous solutions of low molecular weight alcohols (methanol, ethylene glycol and glycerol) at the concentrations covering a broad range from 1 to 90 mol %. The work focuses on studying the effect of the alcohols molecules on the hydrogen bonding of water molecules in binary mixtures. By analyzing the hydrogen bonding ability of the hydroxyl (-OH) groups for the three alcohols, it is found that the hydroxyl group of methanol prefers to form more hydrogen bonds than that of ethylene glycol and glycerol due to the intra-and intermolecular effects. It is also shown that concentration has significant effect on the ability of alcohol molecule to hydrogen bond water molecules. Understanding the hydrogen bonding characteristics of the aqueous solutions is helpful to reveal the cryoprotective mechanisms of methanol, ethylene glycol and glycerol in aqueous solutions.

Active trench barrier RC‑IGBT with pinch‑off and carrier accumulation effects

Zikai Wei,Weizhong Chen,Haishi Wang,Haifeng Qin,Zhengsheng Han 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.4

A Reverse Conduction Insulated Gate Bipolar Transistor (RC-IGBT) featuring an Active Trench Barrier (ATB) based on Super-Junction (SJ) technology is proposed and investigated. The double-trench gates are designed at the N-pillar and P-pillar of the SJ drift. Consequently, a p-type ATB located between the two trench gates is formed. The ATB working mechanism is controlled and modulated by the Gate Voltage (VGE) of the double-trench gates. In the forward conduction state, the ATB channel is depleted and automatically pinched off by the positive VGE. Thus, the barrier potential of the ATB is remarkably improved. Additionally, holes accumulate underneath the ATB and maintain high conductivity modulation of the SJ drift region. Thus, the low on-state voltage drop (VON) is obtained. In the reverse conduction state, the ATB pinch-off effect automatically fades away with the grounded VGE. In addition, the ATB, P-pillar, and N + act as the anode, drift, and cathode of the Free-Wheeling Diode (FWD), respectively. Electrons are blocked and accumulated by the trench gates. Thus, the hole injection is enhanced and the reverse conduction voltage (VR) is reduced. In the turn-off state, excessive holes can be effectively extracted by the extra ATB channel, and the turn-off loss (EOFF) is remarkably decreased. As a result, the trade-off relationship between VON and EOFF can be significantly improved, which achieves the best comprehensive property when compared with the conventional RC-IGBT and SJ-IGBT.

Modulus of Subgrade Reaction for Circular Tunnels considering Bedrock and Ground Surface

Wusheng Zhao,Peiyao Xie,Weizhong Chen,Changkun Qin 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.6

The modulus of subgrade reaction is a key parameter used in tunnel design. However, the existing analytical relations for determining the modulus mainly focus on deep tunnels in the homogeneous ground. Therefore, the complex variable method was used to develop analytical solutions for calculating the modulus of subgrade reaction for deep circular tunnels close to bedrock and shallow circular tunnels under uniform and oval deformation patterns. Subsequently, the analytical solutions were validated by comparing them with numerical solutions. At last, parametric studies were conducted to analyze the impacts of the bedrock and ground surface on the modulus of subgrade reaction. The results show that the modulus increases substantially near the bedrock and decreases slightly away from the bedrock, while the ground surface has the opposite effect. In addition, the effects of the bedrock and the ground surface on the radial modulus are more significant than that on the tangential modulus. Furthermore, the results confirm the effect of the tunnel deformation pattern on the modulus of subgrade reaction. The analytical solutions may be used for obtaining the approximate magnitude of the modulus of subgrade reaction in the structure design of shallow tunnels and deep tunnels close to bedrock.

Molecular Dynamics Investigation of the Effects of Concentration on Hydrogen Bonding in Aqueous Solutions of Methanol, Ethylene Glycol and Glycerol

Zhang, Ning,Li, Weizhong,Chen, Cong,Zuo, Jianguo,Weng, Lindong Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.9

Hydrogen bonding interaction between alcohols and water molecules is an important characteristic in the aqueous solutions of alcohols. In this paper, a series of molecular dynamics simulations have been performed to investigate the aqueous solutions of low molecular weight alcohols (methanol, ethylene glycol and glycerol) at the concentrations covering a broad range from 1 to 90 mol %. The work focuses on studying the effect of the alcohols molecules on the hydrogen bonding of water molecules in binary mixtures. By analyzing the hydrogen bonding ability of the hydroxyl (-OH) groups for the three alcohols, it is found that the hydroxyl group of methanol prefers to form more hydrogen bonds than that of ethylene glycol and glycerol due to the intra-and intermolecular effects. It is also shown that concentration has significant effect on the ability of alcohol molecule to hydrogen bond water molecules. Understanding the hydrogen bonding characteristics of the aqueous solutions is helpful to reveal the cryoprotective mechanisms of methanol, ethylene glycol and glycerol in aqueous solutions.

Ultrahigh Energy Storage Capacitance and High Breakdown Strength in Biaxially Oriented Poly(vinylidene fluoride) Using a High-Electric-Induced Technique

Hongwei Lu,Jianxin Du,Cuiping Yu,Xingping Wang,Yanlin Gao,Weizhong Xu,Aiping Liu,Xiaoxiao Lu,Yingxin Chen 한국고분자학회 2020 Macromolecular Research Vol.28 No.6

The development of high dielectric materials with high energy densities is a crucial research domain in the modern microelectronics and power systems. The objective of this work was to develop the highly ordered crystal orientations and large ferroelectric crystalline β/γ-phases in the biaxially oriented poly(vinylidene fluoride) (BOPVDF). Importantly, a high discharged energy density and high dielectric constant was achieved by using a high-electric-induced technique. A suitable poling electric field was applied to the BOPVDF films in order to enhance the breakdown strength. Remarkably, the BOPVDF film poled at the electric field of 113 MV m-1 achieved an unprecedented discharged energy density of 25.4 J cm-3 at an ultra-high electric field of 550 MV m-1, which is by far the highest value ever achieved in flexible polymer-based capacitor films. Comparatively, the unpoled BOPVDF and commercial biaxially oriented polypropylene (BOPP) exhibited only a discharged energy density of 7.9 J cm-3 and 1.2 J cm-3, respectively. This systematic study provides a new design paradigm to exploit PVDF-based dielectric polymers for capacitor applications.

DATCN: Deep Attention fused Temporal Convolution Network for the prediction of monitoring indicators in the tunnel

Junchen Ye,Bowen Du,Zhixin Zhang,Xuyan Tan,Wentao Li,Weizhong Chen 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.30 No.6

The prediction of structural mechanical behaviors is vital important to early perceive the abnormal conditions and avoid the occurrence of disasters. Especially for underground engineering, complex geological conditions make the structure more prone to disasters. Aiming at solving the problems existing in previous studies, such as incomplete consideration factors and can only predict the continuous performance, the deep attention fused temporal convolution network (DATCN) is proposed in this paper to predict the spatial mechanical behaviors of structure, which integrates both the temporal effect and spatial effect and realize the cross-time prediction. The temporal convolution network (TCN) and self-attention mechanism are employed to learn the temporal correlation of each monitoring point and the spatial correlation among different points, respectively. Then, the predicted result obtained from DATCN is compared with that obtained from some classical baselines, including SVR, LR, MLP, and RNNs. Also, the parameters involved in DATCN are discussed to optimize the prediction ability. The prediction result demonstrates that the proposed DATCN model outperforms the state-of-the-art baselines. The prediction accuracy of DATCN model after 24 hours reaches 90 percent. Also, the performance in last 14 hours plays a domain role to predict the short-term behaviors of the structure. As a study case, the proposed model is applied in an underwater shield tunnel to predict the stress variation of concrete segments in space.