Impact of Energy Relaxation of Channel Electrons on Drain- Induced Barrier Lowering in Nano-Scale Si-Based MOSFETs

Ling-Feng Mao 한국전자통신연구원 2017 ETRI Journal Vol.39 No.2

Drain-induced barrier lowering (DIBL) is one of the main parameters employed to indicate the short-channel effect for nano metal-oxide semiconductor field-effect transistors (MOSFETs). We propose a new physical model of the DIBL effect under two-dimensional approximations based on the energy-conservation equation for channel electrons in FETs, which is different from the former field-penetration model. The DIBL is caused by lowering of the effective potential barrier height seen by the channel electrons because a lateral channel electric field results in an increase in the average kinetic energy of the channel electrons. The channel length, temperature, and doping concentration-dependent DIBL effects predicted by the proposed physical model agree well with the experimental data and simulation results reported in Nature and other journals.

Study of the Effects of the Antisite Related Defects in Silicon Dioxide of Metal-Oxide-Semiconductor Structure on the Gate Leakage Current

Mao, Ling-Feng,Wang, Zi-Ou,Xu, Ming-Zhen,Tan, Chang-Hua The Institute of Electronics and Information Engin 2008 Journal of semiconductor technology and science Vol.8 No.2

The effects of the antisite related defects on the electronic structure of silica and the gate leakage current have been investigated using first-principles calculations. Energy levels related to the antisite defects in silicon dioxide have been introduced into the bandgap, which are nearly 2.0 eV from the top of the valence band. Combining with the electronic structures calculated from first-principles simulations, tunneling currents through the silica layer with antisite defects have been calculated. The tunneling current calculations show that the hole tunneling currents assisted by the antisite defects will be dominant at low oxide field whereas the electron direct tunneling current will be dominant at high oxide field. With increased thickness of the defect layer, the threshold point where the hole tunneling current assisted by antisite defects in silica is equal to the electron direct tunneling current extends to higher oxide field.

Modeling negative and positive temperature dependence of the gate leakage current in GaN high-electron mobility transistors

Ling-Feng Mao 한국전자통신연구원 2022 ETRI Journal Vol.44 No.3

Monte Carlo simulations show that, as temperature increases, the average kinetic energy of channel electrons in a GaN transistor first decreases and then increases. According to the calculations, the relative energy change reaches 40%. This change leads to a reduced barrier height due to quantum coupling among the three-dimensional motions of channel electrons. Thus, an analysis and physical model of the gate leakage current that includes drift velocity is proposed. Numerical calculations show that the negative and positive temperature dependence of gate leakage currents decreases across the barrier as the field increases. They also demonstrate that source–drain voltage can have an effect of 1 to 2 orders of magnitude on the gate leakage current. The proposed model agrees well with the experimental results.

Effects of Channel Electron In-Plane Velocity on the Capacitance-Voltage Curve of MOS Devices

Ling-Feng Mao 한국전자통신연구원 2010 ETRI Journal Vol.32 No.1

The coupling between the transverse and longitudinal components of the channel electron motion in NMOS devices leads to a reduction in the barrier height. Therefore, this study theoretically investigates the effects of the in-plane velocity of channel electrons on the capacitance-voltage characteristics of nano NMOS devices under inversion bias. Numerical calculation via a self-consistent solution to the coupled Schrödinger equation and Poisson equation is used in the investigation. The results demonstrate that such a coupling largely affects capacitance-voltage characteristic when the in-plane velocity of channel electrons is high. The ballistic transport ensures a high in-plane momentum. It suggests that such a coupling should be considered in the quantum capacitance-voltage modeling in ballistic transport devices.

Study of the Effects of the Antisite Related Defects in Silicon Dioxide of Metal-Oxide-Semiconductor Structure on the Gate Leakage Current

Ling-Feng Mao,Zi-Ou Wang,Ming-Zhen Xu,Chang-Hua Tan 대한전자공학회 2008 Journal of semiconductor technology and science Vol.8 No.2

The effects of the antisite related defects on the electronic structure of silica and the gate leakage current have been investigated using first-principles calculations. Energy levels related to the antisite defects in silicon dioxide have been introduced into the bandgap, which are nearly 2.0 eV from the top of the valence band. Combining with the electronic structures calculated from first-principles simulations, tunneling currents through the silica layer with antisite defects have been calculated. The tunneling current calculations show that the hole tunneling currents assisted by the antisite defects will be dominant at low oxide field whereas the electron direct tunneling current will be dominant at high oxide field. With increased thickness of the defect layer, the threshold point where the hole tunneling current assisted by antisite defects in silica is equal to the electron direct tunneling current extends to higher oxide field.

Genomic Sequence Analysis and Organization of BmKαTx11 and BmKαTx15 from Buthus martensii Karsch: Molecular Evolution of α-toxin genes

Xiu Ling Xu,Zhi Jian Cao,Ji Qun Sheng,Wen Lan Wu,Feng Luo,Yong Gang Sha,Xin Mao,Hui Liu,Da He Jiang,Wen Xin Li 한국생활환경학회 2005 BMB Reports Vol.38 No.4

Clinical Significance of C-X-C Motif Chemokine Receptor 4 and Integrin αvβ6 Expression in Breast Cancer

Hongshan Huang,Mengci Yuan,Shuang-Ling Wu,Jinling Ba,Xinmiao Yu,Xiaoyun Mao,Feng Jin 한국유방암학회 2020 Journal of breast cancer Vol.23 No.2

Purpose: C-X-C motif chemokine receptor 4 (CXCR4) and integrin αvβ6 play important roles in the malignant progression of multiple cancers. However, it remains unclear whether the expression of one or both proteins in breast cancer (BC) is of clinical significance. In this study, we investigated the expression of CXCR4 and integrin αvβ6 in BC tissues and their correlation with clinicopathological characteristics, including survival. Methods: CXCR4 and αvβ6 expression in 111 BC tissues was examined by immunocytochemistry. Correlations between the expression of the 2 proteins and patient clinicopathological characteristic were investigated using the Kaplan–Meier method and the Cox proportional hazards model. Results: CXCR4 and αvβ6 were overexpressed in BC tissue compared with normal breast tissue. Overexpression of both molecules was related to lymph node status (p = 0.013 and p = 0.022, respectively). αvβ6 overexpression was also associated with tumor size (p = 0.044). A positive correlation was detected between the expression of CXCR4 and αvβ6 (r = 0.649, p = 0.001), and co-overexpression of both molecules was associated with tumor size (p = 0.018) and lymph node metastasis (p = 0.015). Kaplan–Meier analysis revealed that overexpression of CXCR4, αvβ6, or both molecules was associated with short overall survival (OS; p < 0.001, p < 0.001, and p = 0.009, respectively) and disease-free survival (DFS; p < 0.001, p = 0.005, and p = 0.019, respectively). Multivariate analysis indicated that lymph node metastasis was an independent prognostic factor for unfavorable OS and DFS (p = 0.002 and p = 0.005, respectively), whereas co-overexpression of CXCR4 and αvβ6 was an independent prognostic factor only for OS (p = 0.043). Conclusion: CXCR4 and αvβ6 may play synergistic roles in the progression of BC, and co-targeting of CXCR4 and αvβ6 could be a potential strategy for the prevention and treatment of BC

Structure properties and electrical mechanisms of Si(001)/SiO2 interface with varying Si layer thickness in nano-scale transistor

Haixia Li,Aiming Ji,Canyan Zhu,Ling-Feng Mao 한국물리학회 2018 Current Applied Physics Vol.18 No.9

To illustrate the impacts of stress/strain effect on nano-scale transistor, a theoretical investigation of stress/strain and transition region of interface are presented in this paper. It is found that the residual stress changes from −1.8098 to 0.3159 GPa with Si layer thickness increasing. At the same time, SiSi average bond length reduces from 2.397Å to 2.355 Å and finally approaches to 2.352 Å (the bond length of ideal silicon crystal). The further calculations demonstrate that the above mentioned changes also decrease surface potential. And the relative decrease in the surface potential becomes larger with the applied gate voltage decreasing especially when it is less than 1.5 V. Moreover, when the doping concentration is 1 × 1019cm−3, the threshold voltage and subthreshold swing (SS) reduce from 2.9 V to 2 V and 551mV/dec to 198mV/dec respectively. It implies that we can get a better device performance by growing appropriate thickness of silicon.

A Novel EYA1 Mutation Causing Alternative RNA Splicing in a Chinese Family With Branchio-Oto Syndrome: Implications for Molecular Diagnosis and Clinical Application

Anhai Chen,Chufeng He,Yong Feng,Jie Ling,Xin Peng,Xianlin Liu,Shuang Mao,Yongjia Chen,Mengyao Qin,Shuai Zhang,Yijiang Bai,Jian Song,Zhili Feng,Lu Ma,Dinghua He,Lingyun Mei1 대한이비인후과학회 2023 Clinical and Experimental Otorhinolaryngology Vol.16 No.4

Objectives. Branchio-oto syndrome (BOS) primarily manifests as hearing loss, preauricular pits, and branchial defects. EYA1is the most common pathogenic gene, and splicing mutations account for a substantial proportion of cases. However,few studies have addressed the structural changes in the protein caused by splicing mutations and potential pathogenicfactors, and several studies have shown that middle-ear surgery has limited effectiveness in improving hearing in thesepatients. BOS has also been relatively infrequently reported in the Chinese population. This study explored the ge-netic etiology in the family of a proband with BOS and provided clinical treatment to improve the patient’s hearing. Methods. We collected detailed clinical features and peripheral blood samples from the patients and unaffected individualswithin the family. Pathogenic mutations were identified by whole-exome sequencing and cosegregation analysis andclassified according to the American College of Medical Genetics and Genomics guidelines. Alternative splicing wasverified through a minigene assay. The predicted three-dimensional protein structure and biochemical experimentswere used to investigate the pathogenicity of the mutation. The proband underwent middle-ear surgery and was fol-lowed up at 1 month and 6 months postoperatively to monitor auditory improvement. Results. A novel heterozygous EYA1 splicing variant (c.1050+4 A >C) was identified and classified as pathogenic (PVS1(RNA),PM2, PP1). Skipping of exon 11 of the EYA1 pre-mRNA was confirmed using a minigene assay. This mutation mayimpair EYA1-SIX1 interactions, as shown by an immunoprecipitation assay. The EYA1-Mut protein exhibited cellularmislocalization and decreased protein expression in cytological experiments. Middle-ear surgery significantly improvedhearing loss caused by bone-conduction abnormalities in the proband. Conclusion. We reported a novel splicing variant of EYA1 in a Chinese family with BOS and revealed the potential molec-ular pathogenic mechanism. The significant hearing improvement observed in the proband after middle-ear surgeryprovides a reference for auditory rehabilitation in similar patients.

Multilocus Sequence Typing and Virulence Factors Analysis of Escherichia coli O157 Strains in China

Xiao W. Ji,Ya L. Liao,Ye F. Zhu,Hai G. Wang,Ling Gu,Jiang Gu,Chen Dong,Hong L. Ding,Xu H. Mao,Feng C. Zhu,Quan M. Zou 한국미생물학회 2010 The journal of microbiology Vol.48 No.6

Escherichia coli O157:H7, an important food-borne pathogen, has become a major public health concern worldwide. The aim of this study was to investigate the molecular epidemiologic feature of E. coli O157:H7strains in China. 105 E. coli O157:H7 isolates were collected from various hosts and places over 9 years. A multilocus sequence typing scheme (MLST) was applied for bacteria genotyping and polymerase chain reaction (PCR) was used for virulence factor identification. Seven new MLST sequence types (STs), namely ST836, ST837, ST838, ST839, ST840, ST841, and ST842 were identified, which grouped into two lineages. Phylogenetic analysis suggested that the most two frequent STs in China, ST837 and ST836, may be the derivatives of E. coli O157:H7 Sakai or E. coli O157:H7 EDL933. Geographical diversity and host variety of E. coli O157:H7 were observed in China. In addition, the different distribution of tccp was detected. The data presented herein provide new insights into the molecular epidemiologic feature of E. coli O157:H7, and aid in the investigation of the transmission regularity and evolutionary mechanism of E. coli O157:H7.