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| 1 | Ferroelectricity in dopant-free HfO_(2) thin films prepared by pulsed laser deposition显示文摘As a high-k material,hafnium oxide(HfO_(2))has been used in gate dielectrics for decades.Since the discovery of polar phase in Si-doped HfO_(2) films,chemical doping has been widely demonstrated as an effective approach to stabilize the ferroelectric phase in HfO_(2) based thin films.However,the extra capping layer deposition,post-growth annealing and wake-up effect are usually required to arouse the ferroelectricity in HfO_(2) based thin films,resulting in the increase of complexity for sample synthesis and the impediment of device application.In this study,the ferroelectricity is observed in non-capped dopant-free HfO_(2) thin films prepared by pulsed laser deposition(PLD)without post-growth annealing.By adjusting the deposited temperature,oxygen pressure and thickness,the maximum polarization up to 14.7 m C/cm^(2) was obtained in 7.4 nm-thick film.The fraction of orthorhombic phase,concentrations of defects and size effects are considered as possible mechanisms for the influences of ferroelectric prop-erties.This study indicates that PLD is an effective technique to fabricate high-quality ferroelectric HfO_(2) thin films in the absence of chemical doping,capping layer deposition and post-growth annealing,which may boost the process of nonvolatile memory device application. | Yongjian Luo Zhenxun Tang Xiaozhe Yin Chao Chen Zhen Fan Minghui Qin Min Zeng Guofu Zhou Xingsen Gao Xubing Lu Jiyan Dai Deyang Chen Jun-Ming Liu | 2022 | Journal of Materiomics2022,8,2: | 1 |
| 2 | Enhanced ferroelectric polarization with less wake-up effect and improved endurance of Hf_(0.5)Zr_(0.5)O_(2)thin films by implementing W electrode显示文摘This paper reports the improvement of electrical,ferroelectric and endurance of Hf_(0.5)Zr_(0.5)O_(2)(HZO)thinfilm capacitors by implementing W electrode.The W/HZO/W capacitor shows excellent pristine 2 P_(r)values of 45.1 gC/cm^(2)at±6 V,which are much higher than those of TiN/HZO/W(34.4μC/cm^(2))and W/HZO/TiN(26.9μC/cm^(2))capacitors.Notably,the maximum initial 2 P_(r)value of W/HZO/W capacitor can reach as high as 57.9μC/cm^(2)at±7.5 V.These strong ferroelectric polarization effects are ascribed to the W electrode with a fairly low thermal expansion coefficient which provides a larger in-plane tensile strain compared with TiN electrode,allowing for enhancement of o-phase formation.Moreover,the W/HZO/W capacitor also exhibits higher endurance,smaller wake-up effect(10.1%)and superior fatigue properties up to 1.5×10^(10)cycles compared to the TiN/HZO/W and W/HZO/TiN capacitors.Such improvements of W/HZO/W capacitor are mainly due to the decreased leakage current by more than an order of magnitude compared to the W/HZO/TiN capacitor.These results demonstrate that capping electrode material plays an important role in the enhancement of o-phase formation,reduces oxygen vacancies,mitigates wake-up effect and improves reliability. | Dao Wang Yan Zhang Jiali Wang Chunlai Luo Ming Li Wentao Shuai Ruiqiang Tao Zhen Fan Deyang Chen Min Zeng Jiyan Y.Dai Xubing B.Lu J-M.Liu | 2022 | Journal of Materials Science & Technology2022,,9: | 1 |
| 3 | Short-form OPA1 is a molecular chaperone in mitochondrial intermembrane space显示文摘Mitochondria,double-membrane organelles,are known to participate in a variety of metabolic and signal transduction pathways.The intermembrane space(IMS)of mitochondria is proposed to subject to multiple damages emanating from the respiratory chain.The optic atrophy 1(OPA1),an important protein for mitochondrial fusion,is cleaved into soluble short-form(S-OPA1)under stresses.Here we report that S-OPA1 could function as a molecular chaperone in IMS.We purified the S-OPA1(amino acid sequence after OPA1 isoform 5 S1 site)protein and showed it protected substrate proteins from thermally and chemically induced aggregation and strengthened the thermotolerance of Escherichia coli(E.coli).We also showed that S-OPA1 conferred thermotolerance on IMS proteins,e.g.,neurolysin.The chaperone activity of S-OPA1 may be required for maintaining IMS homeostasis in mitochondria. | Deyang Yao Yukun Li Sheng Zeng Zhifan Li Zahir Shah Bigui Song Jinglei Liu Yi Wu Liang Yang Qi Long Wenqian Wang Zhijuan Hu Haite Tang Xingguo Liu | 2022 | Science China(Life Sciences)2022,65,2: | 1 |
| 4 | Experimental search for high-performance ferroelectric tunnel junctions guided by machine learning显示文摘Ferroelectric tunnel junction(FTJ)has attracted considerable attention for its potential applications in nonvolatile memory and neuromorphic computing.However,the experimental exploration of FTJs with high ON/OFF ratios is a challenging task due to the vast search space comprising of ferroelectric and electrode materials,fabrication methods and conditions and so on.Here,machine learning(ML)is demonstrated to be an effective tool to guide the experimental search of FTJs with high ON/OFF ratios.A dataset consisting of 152 FTJ samples with nine features and one target attribute(i.e.,ON/OFF ratio)is established for ML modeling.Among various ML models,the gradient boosting classification model achieves the highest prediction accuracy.Combining the feature importance analysis based on this model with the association rule mining,it is extracted that the utilizations of{graphene/graphite(Gra)(top),LaNiO_(3)(LNO)(bottom)}and{Gra(top),Ca_(0.96)Ce_(0.04)MnO_(3)(CCMO)(bottom)}electrode pairs are likely to result in high ON/OFF ratios in FTJs.Moreover,two previously unexplored FTJs:Gra/BaTiO_(3)(BTO)/LNO and Gra/BTO/CCMO,are predicted to achieve ON/OFF ratios higher than 1000.Guided by the ML predictions,the Gra/BTO/LNO and Gra/BTO/CCMO FTJs are experimentally fabricated,which unsurprisingly exhibit≥1000 ON/OFF ratios(~8540 and~7890,respectively).This study demonstrates a new paradigm of developing high-performance FTJs by using ML. | Jingjing Rao Zhen Fan Qicheng Huang Yongjian Luo Xingmin Zhang Haizhong Guo Xiaobing Yan Guo Tian Deyang Chen Zhipeng Hou Minghui Qin Min Zeng Xubing Lu Guofu Zhou Xingsen Gao Jun-Ming Liu | 2022 | Journal of Advanced Dielectrics2022,12,3: | 0 |
| 5 | Creation and erasure of polar bubble domains in PbTiO_(3)films by mechanical stress and light illuminations显示文摘The controllable manipulation of polar topological structures(e.g.skyrmion bubble)in ferroelectric materials have been considered as a cornerstone for future programmable nano-electronics.Here,we present the effective creation and erasure of polar bubble states PbTiO_(3)(PTO)multilayers trigged by mechanical stress and light illumination,respectively.It was found that applying atomic force microscope(AFM)tip force can induced formation of nanoscale bubble domains from the initial monodomain state.Moreover,the created bubble domain can be eliminated by exposure to ultraviolet or infrared light illumination.The above results can be understood by modulation of depolarization screening charges and bias fields,as reflected by scanning Kelvin potential microscopic(SKPM)observations,whereby the flexoelectric effect from the tip force tends to remove the screening charges on top surface and modulate the bias field that favors the formation of bubble state while light illumination tends to recover the screen charges and favor the monodomain state.The results provide a good example for multi-field manipulation of polar topologies,which might create a new avenue towards the immerging new concept electronic devices. | Xingchen Zhang Hongying Chen Guo Tian Wenda Yang Zhen Fan Zhipeng Hou Deyang Chen Min Zeng Minghui Qin Jinwei Gao Xingsen Gao Jun-Ming Liu | 2023 | Journal of Materiomics2023,9,4: | 0 |
| 6 | Exploring the psychological impact of the 2022 SARS-CoV-2 Omicron variant outbreak in China显示文摘To the editor:The impact of the coronavirus disease 2019(COVID-19)pandemic in 2020 on mental health was substantialin Chinai2and various other countries.34 Beyond the direct consequences of COVID-19,the pandemic created an environment in which many determinants of mental health were affected.Issues associated with the pandemic,such as loss of livelihood,limited access to medical services,reduced social interactions,and economic downturn,could potentially have adverse effects on the population's mental well-being.5 In November 2021,the World Health Organization(WHO)designated the new variant of the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),variant B.1.1.529,as a variant of concern and named it Omicron;its rapid mutation and spread raised a new global health concern. | Gangbin Han Guirong Cheng Feifei Hu Chunli Li Dan Liu Juan Zhou Jing Liu Linya Huang Xiaochang Liu Qianqian Nie Dan Song Deyang Zeng Lang Xu Jinquan Li Yushan Chen Zhen Wei Qiong Wu Xiaoming He Qingming Wu Wei Tan Yufei Mei Xingxing Chen Yangming Ou Jingjing ZhangYafu Yu Mengliu Yang Pengfei Lian Fukai Zhou Renjia Fan Hong Wan Chenlu Hu Yidi Fu Shiyue Li Junyi Wang Cheng Cai Mengdie Pei Yuyang Cui Wanying Cai Yiqing Li Shiyao Pan Chang Chen Yan He Zhaoxia Wu Liu Hu Liang Tao Hongyan Xiao Xinyan Xie Yan Zeng | 2023 | General Psychiatry2023,36,6: | 0 |