Our two newly obtained high-quality 40Ar/39Ar ages suggest that the high-K volcanic rocks of the Lawuxiang Formation in the Mangkang basin, Tibet were formed at 33.5 ( 0.2 Ma. The tracing of elemental and Pb-Sr-Nd iso...Our two newly obtained high-quality 40Ar/39Ar ages suggest that the high-K volcanic rocks of the Lawuxiang Formation in the Mangkang basin, Tibet were formed at 33.5 ( 0.2 Ma. The tracing of elemental and Pb-Sr-Nd isotopic geochemistry indicates that they were derived from an EM2 enriched mantle in continental subduction caused by transpression. Their evidently negative anomalies in HFSEs such as Nb and Ta make clear that there is an input of continental material into the mantle source. The high-K rocks at 33.5 ( 0.2 Ma in the Mangkang basin may temporally, spatially and compositionally compare with the early one of two-pulse high-K rocks in eastern Tibet distinguished by Wang J. H. Et al., implying that they were formed in the same tectonic setting.展开更多
Volcanic rocks in the study area, including dacite, trachyandesite and mugearite, belong to the intermediate-acid, high-K calc-alkaline series, and possess the characteristics of adakite. The geochemistry of the rocks...Volcanic rocks in the study area, including dacite, trachyandesite and mugearite, belong to the intermediate-acid, high-K calc-alkaline series, and possess the characteristics of adakite. The geochemistry of the rocks shows that the rocks are characterized by SiO2>59%, enrichment in A12O3(15.09-15.64%) and Na2O (>3.6%), high Sr (649-885 μg/g) and Sc, low Y contents (<17 μg/g), depletion in HREE (Yb<1.22 μg/g), (La/Yb)N>25, Sr/Y>40, MgO<3% (Mg<0.35), weak Eu anomaly (Eu/Eu=0.84-0.94), and lack of the high field strength elements (HFSE) (Nb, Ta, Ti, etc.). The Nd and Sr isotope data (87Sr/86Sr=0.7062-0.7079, 143Nd/144Nd=0.51166-0.51253, εNd= -18.61-0.02), show that the magma resulted from partial melting (10%-40%) of newly underplated basaltic lower crust under high pressure (1-4 GPa), and the petrogenesis is obviously affected by the crust's assimilation and fractional crystallization (AFC). This research will give an insight into the uplift mechanism of the Tibetan plateau.展开更多
The previously published U-Pb and 40Ar/39Ar ages and our 21 newly-obtained 40Ar/39Ar ages suggest that the Cenozoic magmatism in eastern Tibet and Indochina occurred in two episodes, each with distinctive geochemical ...The previously published U-Pb and 40Ar/39Ar ages and our 21 newly-obtained 40Ar/39Ar ages suggest that the Cenozoic magmatism in eastern Tibet and Indochina occurred in two episodes, each with distinctive geochemical signatures, at (40—28) Ma and (16—0) Ma. The older rocks are localized along the major strike-slip faults such as the Jinsha-Red River fault system and erupted synchronously with transpression. The younger rocks are widely distributed in rift basins and coeval with the east-west extension of Tibet and eastern Asia. Combining with their geochemical data, we consider that the earlier magmatic phase was generated by continental subduction, while the later volcanic phase was caused by decompression melting of a recently meta- somatically-altered, depleted mantle source. The magmatic gap between the two igneous pulses represents an important geodynamic transition in the evolution of eastern Tibet, from the processes controlled mainly by crustal deformation to those largely dominated by mantle tectonics.展开更多
Molybdenum ditelluride （MoTe2） has been demonstrated great potential in electronic and optoelectronic applications. However, the reported effective hole mobility remains far below its theoretical value. Herein, taki...Molybdenum ditelluride （MoTe2） has been demonstrated great potential in electronic and optoelectronic applications. However, the reported effective hole mobility remains far below its theoretical value. Herein, taking advantage of high-κ screening effect, we have fabricated back-gated MoTe2 transistors on an Al2O3 high-κ dielectric and systematically investigated the electronic and optoelectronic proper- ties. A high current on/off ratio exceeding 106 is achieved in the Al2O3-based MoTe2 transistors, and the hole mobility is demonstrated to be 150 cm2 V^-1 s^-1, compared to 0.2-20 cm^2 V^-1 s^-1 ever obtained from back-gated MoTe2 transistors in the literatures. Moreover, a considerable hole concentration of 1.2 × 10^13 cm 2 is attained in our Al2O3-based MoTe2 transistors owing to the strong gate control capa- bility, leading to a high on-state hole current of 6.1 μA μm^-1. After optimization, our Al2O3-based MoTe2 phototransistor exhibits outstanding photodetective performance, with a high responsivity of 543 AW^-1 and a high photogain of 1,662 at 405 nm light illumination, which are boosted around 419 times compared to the referential SiO2-based control devices. The mechanisms of photoconductivity in the Al2O3-based MoTe2 phototransistors have been analyzed in detail, and the photogating effect is considered to play an important role. This work may provide useful insight to improve carrier mobility in two-dimensional layered semiconductors and open opportunities to facilitate the development of high-performance photodetectors in the future.展开更多
Configuration-constrained potential-energy-surface calculations are performed to investigate high-K isomers in97Y,130Ba,176Yb,177Lu,and178Hf that were observed to have increased electric quadrupole moments but decreas...Configuration-constrained potential-energy-surface calculations are performed to investigate high-K isomers in97Y,130Ba,176Yb,177Lu,and178Hf that were observed to have increased electric quadrupole moments but decreased charge radii relative to the states on which they are built.Taking into account the efects of deformation change and unpaired protons,our calculations can reproduce the enhancement of electric quadrupole moments for the isomers in97Y,130Ba,176Yb,177Lu and the Kπ=8 isomer in178Hf,and can reproduce the reduction of charge radii for the Kπ=27/2 isomer in97Y and the Kπ=16+isomer in178Hf.展开更多
二硫化钨(WS_(2))属于过渡金属硫族化合物(TMDs)材料,具有较宽的可调带隙(1.3~2.1 e V),缺陷密度相对较低,且有超高的表面积比,可通过外界掺杂或相变处理来改善载流子传输性能,在低功耗场效应晶体管和超灵敏光电探测器等领域有广阔的应...二硫化钨(WS_(2))属于过渡金属硫族化合物(TMDs)材料,具有较宽的可调带隙(1.3~2.1 e V),缺陷密度相对较低,且有超高的表面积比,可通过外界掺杂或相变处理来改善载流子传输性能,在低功耗场效应晶体管和超灵敏光电探测器等领域有广阔的应用前景。采用微机械剥离的方法将多层WS_(2)薄膜转移到氧化铪(HfO2)介质层上,制备出具有高栅控、低功耗的WS_(2)背栅场效应晶体管,通过注入三乙胺(TEA)实现WS_(2)薄膜的表面电子掺杂。实验结果表明,修饰后的多层WS_(2)薄膜的面内振动模式有轻微位移,拉曼特征峰强度变弱,证明三乙胺溶液能有效增加WS_(2)薄膜内的电子浓度;薄膜与金属电极之间的欧姆接触良好,器件的电子迁移率由10.87 cm^(2)·V^(-1)·s^(-1)提升到24.89 cm^(2)·V^(-1)·s^(-1),室温下的电流开关比保持在106,亚阈值摆幅为190.11 m V/dec。结合理论分析TEA对WS_(2)原子薄层的掺杂机理,TEA通过表面电荷转移的方式来增加WS_(2)半导体内的电子浓度,完成WS_(2)背栅场效应晶体管的n型掺杂。器件较高的电流开关比及电子迁移率的提升证明了TEA的表面修饰能有效调控多层WS_(2)晶体管器件的电子传输特性。展开更多
To meet the expectation set by Moore’s law on transistors,the search for thickness-scalable high dielectric constant(k)gate layers has become an emergent research frontier.Previous investigations have failed to solve...To meet the expectation set by Moore’s law on transistors,the search for thickness-scalable high dielectric constant(k)gate layers has become an emergent research frontier.Previous investigations have failed to solve the“polarizability–scalability–insulation robustness”trilemma.In this work,we show that this trilemma can be solved by using a gate layer of a high k ferroelectric oxide in its superparaelectric(SPE)state.In the SPE,its polar order becomes local and is dispersed in an amorphous matrix with a crystalline size down to a few nanometers,leading to an excellent dimensional scalability and a good field-stability of the k value.As an example,a stable high k value(37±3)is shown in ultrathin SPE films of(Ba_(0.95),Sr_(0.05))(Zr_(0.2),Ti_(0.8))O_(3)deposited on LaNiO_(3)-buffered Pt/Ti/SiO_(2)/(100)Si down to a 4 nm thickness,leading to a small equivalent oxide thickness of~0.46 nm.The aforementioned characteristic microstructure endows the SPE film a high breakdown strength(~10.5 MV·cm^(−1)for the 4 nm film),and hence ensures a low leakage current for the operation of the complementary metal oxide semiconductor(CMOS)gate.Lastly,a high electrical fatigue resistance is displayed by the SPE films.These results reveal a great potential of superparaelectric materials as gate dielectrics in the next-generation microelectronics.展开更多
Al2O3and HfO2thin films are separately deposited on n-type InAlAs epitaxial layers by using atomic layer deposition(ALD).The interfacial properties are revealed by angle-resolved x-ray photoelectron spectroscopy(AR-XP...Al2O3and HfO2thin films are separately deposited on n-type InAlAs epitaxial layers by using atomic layer deposition(ALD).The interfacial properties are revealed by angle-resolved x-ray photoelectron spectroscopy(AR-XPS).It is demonstrated that the Al2O3layer can reduce interfacial oxidation and trap charge formation.The gate leakage current densities are 1.37×106A/cm2and 3.22×106A/cm2at+1V for the Al2O3/InAlAs and HfO2/InAlAs MOS capacitors respectively.Compared with the HfO2/InAlAs metal-oxide-semiconductor(MOS) capacitor,the Al2O3/InAlAS MOS capacitor exhibits good electrical properties in reducing gate leakage current,narrowing down the hysteresis loop,shrinking stretch-out of the C-V characteristics,and significantly reducing the oxide trapped charge(Qot) value and the interface state density(Dit).展开更多
This paper presents a new silicon-on-insulator(SOI) lateral-double-diffused metal-oxide-semiconductor transistor(LDMOST) device with alternated high-k dielectric and step doped silicon pillars(HKSD device). Due to the...This paper presents a new silicon-on-insulator(SOI) lateral-double-diffused metal-oxide-semiconductor transistor(LDMOST) device with alternated high-k dielectric and step doped silicon pillars(HKSD device). Due to the modulation of step doping technology and high-k dielectric on the electric field and doped profile of each zone, the HKSD device shows a greater performance. The analytical models of the potential, electric field, optimal breakdown voltage, and optimal doped profile are derived. The analytical results and the simulated results are basically consistent, which confirms the proposed model suitable for the HKSD device. The potential and electric field modulation mechanism are investigated based on the simulation and analytical models. Furthermore, the influence of the parameters on the breakdown voltage(BV) and specific on-resistance(R_(on,sp)) are obtained. The results indicate that the HKSD device has a higher BV and lower R_(on,sp) compared to the SD device and HK device.展开更多
The western Kunlun orogen in the northwest Tibet Plateau is related to subduction and collision of Proto-and Paleo-Tethys from early Paleozoic to early Mesozoic. This paper presents new LA-ICPMS zircon U-Pb ages and L...The western Kunlun orogen in the northwest Tibet Plateau is related to subduction and collision of Proto-and Paleo-Tethys from early Paleozoic to early Mesozoic. This paper presents new LA-ICPMS zircon U-Pb ages and Lu-Hf isotopes, whole-rock major and trace elements, and Sr–Nd isotopes of two Ordovician granitoid plutons(466–455 Ma) and their Silurian mafic dikes(～436 Ma) in the western Kunlun orogen. These granitoids show peraluminous high-K calcalkaline characteristics, with(^(87)Sr/^(86)Sr)_i value of 0.7129–0.7224, ε_(Nd)(t) values of -9.3 to -7.0 and zircon ε_(Hf)(t) values of -17.3 to -0.2, indicating that they were formed by partial melting of ancient lower-crust(metaigneous rocks mixed with metasedimentary rocks) with some mantle materials in response to subduction of the Proto-Tethyan Ocean and following collision. The Silurian mafic dikes were considered to have been derived from a low degree of partial melting of primary mafic magma. These mafic dikes show initial ^(87)Sr/^(86)Sr ratios of 0.7101–0.7152 and ε_(Nd)(t) values of -3.8 to -3.4 and zircon ε_(Hf)(t) values of -8.8 to -4.9, indicating that they were derived from enriched mantle in response to post-collisional slab break-off. Combined with regional geology, our new data provide valuable insight into late evolution of the Proto-Tethys.展开更多
The Langdu high-K calc-alkaline intrusions are located in the Zhongdian area, which is the southern part of the Yidun island arc. These intrusive rocks consist mainly of monzonite porphyry, granodiorite, and diorite p...The Langdu high-K calc-alkaline intrusions are located in the Zhongdian area, which is the southern part of the Yidun island arc. These intrusive rocks consist mainly of monzonite porphyry, granodiorite, and diorite porphyry. The K20 content of majority of these rocks is greater than 3%, and, in the K20-SiO2 diagram, all the samples fall into the high-K calc-alkaline to shoshonitic fields. They are enriched in light rare earth elements （LREEs） and depleted in heavy rare earth elements （HREEs; LaN/YbN = 14.3-21.2）, and show slightly negative Eu anomalies （6Eu = 0.77-1.00）. These rocks have high K, Rb, Sr, and Ba contents; moderate to high enrichment of compatible elements （Cr = 36.7-79.9 ppm, Co = 9.6-16.4 ppm, and MgO = 2.2%-3.4%）; low Nb, Ta, and Ti contents, and characteristic of low high field strength elements（HFSEs） versus incompatible elements ratios （Nb/Th = 0.75, Nb/La = 0.34） and incompatible elements ratios （Nb/U = 3.0 and Ce/Pb = 5.1, Ba/Rb = 12.0）. These rocks exhibit restricted Sr and Nd isotopic compositions, with （87Sr/S6Sr）i values ranging from 0.7044 to 0.7069 and ENd（t） values from -2.8 to -2.2. The Sr-Nd isotope systematic and specific trace element ratios suggest that Langdu high-K calc-alkaline intrusive rocks derived from a metasomatized mantle source. The unique geochemical feature of intrusive rocks can be modeled successfully using different members of a slightly enriched mantle, a slab-derived fluid, and terrigenous sediments. It can be inferred that the degree of partial melting and the presence of specific components are temporally related to the tectonic evolution of the Zhongdian island arc. Formation of these rocks can be explained by the various degrees of melting within an ascending region of the slightly enriched mantle, triggered by the subduction of the Garz^--Litang ocean, and an interaction between the slab-derived fluid and the terrigenous sediments.展开更多
An ultralow specific on-resistance high-k LDMOS with vertical field plate（VFP HK LDMOS） is proposed. The high-k dielectric trench and highly doped interface N＋ layer are made in bulk silicon to reduce the surface f...An ultralow specific on-resistance high-k LDMOS with vertical field plate（VFP HK LDMOS） is proposed. The high-k dielectric trench and highly doped interface N＋ layer are made in bulk silicon to reduce the surface field of the drift region in the VFP HK LDMOS. The gate vertical field plate（VFP） pinning in the high-k dielectric trench can modulate the bulk electric field. The high-k dielectric not only provides polarized charges to assist depletion of the drift region, so that the drift region and high-k trench maintain charge balance adaptively,but also can fully assist in depleting the drift region to increase the drift doping concentration and reshape the electric field to avoid premature breakdown. Compared with the conventional structure, the VFP HK LDMOS has the breakdown voltage of 629.1 V at the drift length of 40 μm and the specific on-resistance of 38.4 mΩ·cm^2 at the gate potential of 15 V. Then the power figure of merit is 10.31 MW/cm^2.展开更多
基金This work was jointly supported by the National Natural Science Foundation of China(Grant No.49972026)the Guangdong Natural Science Foundation(Grant No.990531)+1 种基金the project of the ChineseAcademy of Sciences(Grant No.KZCX2-SW-117)the Chinese National Key Project for Basic Research(Grant No.G1998040807)and US NSF.
文摘Our two newly obtained high-quality 40Ar/39Ar ages suggest that the high-K volcanic rocks of the Lawuxiang Formation in the Mangkang basin, Tibet were formed at 33.5 ( 0.2 Ma. The tracing of elemental and Pb-Sr-Nd isotopic geochemistry indicates that they were derived from an EM2 enriched mantle in continental subduction caused by transpression. Their evidently negative anomalies in HFSEs such as Nb and Ta make clear that there is an input of continental material into the mantle source. The high-K rocks at 33.5 ( 0.2 Ma in the Mangkang basin may temporally, spatially and compositionally compare with the early one of two-pulse high-K rocks in eastern Tibet distinguished by Wang J. H. Et al., implying that they were formed in the same tectonic setting.
基金supported jointly by"the Ninth Five-Year Plan"key basic research program(Grant No.9501101-5)the Project of Knowledge Innovation sponsored by the Chinese Academy of Scienoes(Grant No.KZCX2-102the National Outstanding Young Scientists Fund Project(Grant No.49925309)
文摘Volcanic rocks in the study area, including dacite, trachyandesite and mugearite, belong to the intermediate-acid, high-K calc-alkaline series, and possess the characteristics of adakite. The geochemistry of the rocks shows that the rocks are characterized by SiO2>59%, enrichment in A12O3(15.09-15.64%) and Na2O (>3.6%), high Sr (649-885 μg/g) and Sc, low Y contents (<17 μg/g), depletion in HREE (Yb<1.22 μg/g), (La/Yb)N>25, Sr/Y>40, MgO<3% (Mg<0.35), weak Eu anomaly (Eu/Eu=0.84-0.94), and lack of the high field strength elements (HFSE) (Nb, Ta, Ti, etc.). The Nd and Sr isotope data (87Sr/86Sr=0.7062-0.7079, 143Nd/144Nd=0.51166-0.51253, εNd= -18.61-0.02), show that the magma resulted from partial melting (10%-40%) of newly underplated basaltic lower crust under high pressure (1-4 GPa), and the petrogenesis is obviously affected by the crust's assimilation and fractional crystallization (AFC). This research will give an insight into the uplift mechanism of the Tibetan plateau.
基金the National Natural Science Foundation of China(Grat No.49972026) the Natural Science Foundation of Gtangdong (Grat No.990531)+1 种基金 the projects of the Chinese Acadenny of Siences(Grant Nos.KZCX2-SW-117,KZCX2-101) the Chinese National Key Project for Basic Reseacch(Grat No.Gi998040800) and US NSF.
文摘The previously published U-Pb and 40Ar/39Ar ages and our 21 newly-obtained 40Ar/39Ar ages suggest that the Cenozoic magmatism in eastern Tibet and Indochina occurred in two episodes, each with distinctive geochemical signatures, at (40—28) Ma and (16—0) Ma. The older rocks are localized along the major strike-slip faults such as the Jinsha-Red River fault system and erupted synchronously with transpression. The younger rocks are widely distributed in rift basins and coeval with the east-west extension of Tibet and eastern Asia. Combining with their geochemical data, we consider that the earlier magmatic phase was generated by continental subduction, while the later volcanic phase was caused by decompression melting of a recently meta- somatically-altered, depleted mantle source. The magmatic gap between the two igneous pulses represents an important geodynamic transition in the evolution of eastern Tibet, from the processes controlled mainly by crustal deformation to those largely dominated by mantle tectonics.
文摘随着微电子技术的不断发展,MOSFET 的特征尺寸已缩小至100nm 以下,SiO_2作为栅介质材料已不能满足技术发展的需求,因此必须寻求一种新型高 K 的介质材料来取代 SiO_2。当今普遍认为 Hf 基栅介质材料是最有希望取代 SiO_2而成为下一代 MOSFET 的栅介质材料。综述了高 K 栅介质材料的意义、Hf 基高 K 栅介质材料的最新研究进展和 Hf 基高 K 栅介质材料在克服自身缺陷时使用的一些技术;介绍了一款由 Hf 基高 K 介质材料作为栅绝缘层制作的 MOSFET。
基金supported by the National Key Research and Development Program of China(2016YFA0302300,016YFA0200400)the National Science and Technology Major Project of China(2016ZX02301001)+1 种基金the National Natural Science Foundation of China(61306105)the Tsinghua University Initiative Scientific Research Program
文摘Molybdenum ditelluride （MoTe2） has been demonstrated great potential in electronic and optoelectronic applications. However, the reported effective hole mobility remains far below its theoretical value. Herein, taking advantage of high-κ screening effect, we have fabricated back-gated MoTe2 transistors on an Al2O3 high-κ dielectric and systematically investigated the electronic and optoelectronic proper- ties. A high current on/off ratio exceeding 106 is achieved in the Al2O3-based MoTe2 transistors, and the hole mobility is demonstrated to be 150 cm2 V^-1 s^-1, compared to 0.2-20 cm^2 V^-1 s^-1 ever obtained from back-gated MoTe2 transistors in the literatures. Moreover, a considerable hole concentration of 1.2 × 10^13 cm 2 is attained in our Al2O3-based MoTe2 transistors owing to the strong gate control capa- bility, leading to a high on-state hole current of 6.1 μA μm^-1. After optimization, our Al2O3-based MoTe2 phototransistor exhibits outstanding photodetective performance, with a high responsivity of 543 AW^-1 and a high photogain of 1,662 at 405 nm light illumination, which are boosted around 419 times compared to the referential SiO2-based control devices. The mechanisms of photoconductivity in the Al2O3-based MoTe2 phototransistors have been analyzed in detail, and the photogating effect is considered to play an important role. This work may provide useful insight to improve carrier mobility in two-dimensional layered semiconductors and open opportunities to facilitate the development of high-performance photodetectors in the future.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11205120 and 11235001)the National Key Basic Research Program of China (Grant No. 2013CB834400)
文摘Configuration-constrained potential-energy-surface calculations are performed to investigate high-K isomers in97Y,130Ba,176Yb,177Lu,and178Hf that were observed to have increased electric quadrupole moments but decreased charge radii relative to the states on which they are built.Taking into account the efects of deformation change and unpaired protons,our calculations can reproduce the enhancement of electric quadrupole moments for the isomers in97Y,130Ba,176Yb,177Lu and the Kπ=8 isomer in178Hf,and can reproduce the reduction of charge radii for the Kπ=27/2 isomer in97Y and the Kπ=16+isomer in178Hf.
文摘二硫化钨(WS_(2))属于过渡金属硫族化合物(TMDs)材料,具有较宽的可调带隙(1.3~2.1 e V),缺陷密度相对较低,且有超高的表面积比,可通过外界掺杂或相变处理来改善载流子传输性能,在低功耗场效应晶体管和超灵敏光电探测器等领域有广阔的应用前景。采用微机械剥离的方法将多层WS_(2)薄膜转移到氧化铪(HfO2)介质层上,制备出具有高栅控、低功耗的WS_(2)背栅场效应晶体管,通过注入三乙胺(TEA)实现WS_(2)薄膜的表面电子掺杂。实验结果表明,修饰后的多层WS_(2)薄膜的面内振动模式有轻微位移,拉曼特征峰强度变弱,证明三乙胺溶液能有效增加WS_(2)薄膜内的电子浓度;薄膜与金属电极之间的欧姆接触良好,器件的电子迁移率由10.87 cm^(2)·V^(-1)·s^(-1)提升到24.89 cm^(2)·V^(-1)·s^(-1),室温下的电流开关比保持在106,亚阈值摆幅为190.11 m V/dec。结合理论分析TEA对WS_(2)原子薄层的掺杂机理,TEA通过表面电荷转移的方式来增加WS_(2)半导体内的电子浓度,完成WS_(2)背栅场效应晶体管的n型掺杂。器件较高的电流开关比及电子迁移率的提升证明了TEA的表面修饰能有效调控多层WS_(2)晶体管器件的电子传输特性。
基金the National Natural Science Foundation of China(Nos.51772175 and 52002192)the Natural Science Foundation of Shandong Province(Nos.ZR2022ZD39,ZR2020QE042,ZR2022ME031,and ZR2022QB138)+2 种基金the Science,Education and Industry Integration Pilot Projects of Qilu University of Technology(Shandong Academy of Sciences)(Nos.2022GH018 and 2022PY055)Jun Ouyang acknowledges the support from the Jinan City Science and Technology Bureau(No.2021GXRC055)the Education Department of Hunan Province/Xiangtan University(No.KZ0807969).
文摘To meet the expectation set by Moore’s law on transistors,the search for thickness-scalable high dielectric constant(k)gate layers has become an emergent research frontier.Previous investigations have failed to solve the“polarizability–scalability–insulation robustness”trilemma.In this work,we show that this trilemma can be solved by using a gate layer of a high k ferroelectric oxide in its superparaelectric(SPE)state.In the SPE,its polar order becomes local and is dispersed in an amorphous matrix with a crystalline size down to a few nanometers,leading to an excellent dimensional scalability and a good field-stability of the k value.As an example,a stable high k value(37±3)is shown in ultrathin SPE films of(Ba_(0.95),Sr_(0.05))(Zr_(0.2),Ti_(0.8))O_(3)deposited on LaNiO_(3)-buffered Pt/Ti/SiO_(2)/(100)Si down to a 4 nm thickness,leading to a small equivalent oxide thickness of~0.46 nm.The aforementioned characteristic microstructure endows the SPE film a high breakdown strength(~10.5 MV·cm^(−1)for the 4 nm film),and hence ensures a low leakage current for the operation of the complementary metal oxide semiconductor(CMOS)gate.Lastly,a high electrical fatigue resistance is displayed by the SPE films.These results reveal a great potential of superparaelectric materials as gate dielectrics in the next-generation microelectronics.
基金supported by the National Basic Research Program of China(Grant No.2010CB327505)the Advanced Research Foundation of China(Grant No.914xxx803-051xxx111)+3 种基金the National Defense Advance Research Project,China(Grant No.513xxxxx306)the National Natural Science Foundation of China(Grant No.51302215)the Scientific Research Program Funded by Shaanxi Provincial Education Department,China(Grant No.14JK1656)the Science and Technology Project of Shaanxi Province,China(Grant No.2016KRM029)
文摘Al2O3and HfO2thin films are separately deposited on n-type InAlAs epitaxial layers by using atomic layer deposition(ALD).The interfacial properties are revealed by angle-resolved x-ray photoelectron spectroscopy(AR-XPS).It is demonstrated that the Al2O3layer can reduce interfacial oxidation and trap charge formation.The gate leakage current densities are 1.37×106A/cm2and 3.22×106A/cm2at+1V for the Al2O3/InAlAs and HfO2/InAlAs MOS capacitors respectively.Compared with the HfO2/InAlAs metal-oxide-semiconductor(MOS) capacitor,the Al2O3/InAlAS MOS capacitor exhibits good electrical properties in reducing gate leakage current,narrowing down the hysteresis loop,shrinking stretch-out of the C-V characteristics,and significantly reducing the oxide trapped charge(Qot) value and the interface state density(Dit).
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61704084 and 61874059)。
文摘This paper presents a new silicon-on-insulator(SOI) lateral-double-diffused metal-oxide-semiconductor transistor(LDMOST) device with alternated high-k dielectric and step doped silicon pillars(HKSD device). Due to the modulation of step doping technology and high-k dielectric on the electric field and doped profile of each zone, the HKSD device shows a greater performance. The analytical models of the potential, electric field, optimal breakdown voltage, and optimal doped profile are derived. The analytical results and the simulated results are basically consistent, which confirms the proposed model suitable for the HKSD device. The potential and electric field modulation mechanism are investigated based on the simulation and analytical models. Furthermore, the influence of the parameters on the breakdown voltage(BV) and specific on-resistance(R_(on,sp)) are obtained. The results indicate that the HKSD device has a higher BV and lower R_(on,sp) compared to the SD device and HK device.
基金funded by the Strategic Priority Research Program of Chinese Academy of Sciences,Grant No.XDA20070304the Fundamental Research Funds for the Chinese Academy of Geological Sciences(YYWF201601)+1 种基金projects of China Geological Survey(DD20160004,20160083-1,12120115000801,121201101000150014)the National Natural Science Foundation of China(grant 41772232)
文摘The western Kunlun orogen in the northwest Tibet Plateau is related to subduction and collision of Proto-and Paleo-Tethys from early Paleozoic to early Mesozoic. This paper presents new LA-ICPMS zircon U-Pb ages and Lu-Hf isotopes, whole-rock major and trace elements, and Sr–Nd isotopes of two Ordovician granitoid plutons(466–455 Ma) and their Silurian mafic dikes(～436 Ma) in the western Kunlun orogen. These granitoids show peraluminous high-K calcalkaline characteristics, with(^(87)Sr/^(86)Sr)_i value of 0.7129–0.7224, ε_(Nd)(t) values of -9.3 to -7.0 and zircon ε_(Hf)(t) values of -17.3 to -0.2, indicating that they were formed by partial melting of ancient lower-crust(metaigneous rocks mixed with metasedimentary rocks) with some mantle materials in response to subduction of the Proto-Tethyan Ocean and following collision. The Silurian mafic dikes were considered to have been derived from a low degree of partial melting of primary mafic magma. These mafic dikes show initial ^(87)Sr/^(86)Sr ratios of 0.7101–0.7152 and ε_(Nd)(t) values of -3.8 to -3.4 and zircon ε_(Hf)(t) values of -8.8 to -4.9, indicating that they were derived from enriched mantle in response to post-collisional slab break-off. Combined with regional geology, our new data provide valuable insight into late evolution of the Proto-Tethys.
基金supported by the National Science Foundation of China (NSFC) project(41203039)the innovation team of ore-forming dynamics and prediction of concealed deposits, KMUST(2008)
文摘The Langdu high-K calc-alkaline intrusions are located in the Zhongdian area, which is the southern part of the Yidun island arc. These intrusive rocks consist mainly of monzonite porphyry, granodiorite, and diorite porphyry. The K20 content of majority of these rocks is greater than 3%, and, in the K20-SiO2 diagram, all the samples fall into the high-K calc-alkaline to shoshonitic fields. They are enriched in light rare earth elements （LREEs） and depleted in heavy rare earth elements （HREEs; LaN/YbN = 14.3-21.2）, and show slightly negative Eu anomalies （6Eu = 0.77-1.00）. These rocks have high K, Rb, Sr, and Ba contents; moderate to high enrichment of compatible elements （Cr = 36.7-79.9 ppm, Co = 9.6-16.4 ppm, and MgO = 2.2%-3.4%）; low Nb, Ta, and Ti contents, and characteristic of low high field strength elements（HFSEs） versus incompatible elements ratios （Nb/Th = 0.75, Nb/La = 0.34） and incompatible elements ratios （Nb/U = 3.0 and Ce/Pb = 5.1, Ba/Rb = 12.0）. These rocks exhibit restricted Sr and Nd isotopic compositions, with （87Sr/S6Sr）i values ranging from 0.7044 to 0.7069 and ENd（t） values from -2.8 to -2.2. The Sr-Nd isotope systematic and specific trace element ratios suggest that Langdu high-K calc-alkaline intrusive rocks derived from a metasomatized mantle source. The unique geochemical feature of intrusive rocks can be modeled successfully using different members of a slightly enriched mantle, a slab-derived fluid, and terrigenous sediments. It can be inferred that the degree of partial melting and the presence of specific components are temporally related to the tectonic evolution of the Zhongdian island arc. Formation of these rocks can be explained by the various degrees of melting within an ascending region of the slightly enriched mantle, triggered by the subduction of the Garz^--Litang ocean, and an interaction between the slab-derived fluid and the terrigenous sediments.
基金Project supported by the National Natural Science Foundtion of China(No.61404011)the Research and Innovation Project of Graduate Students of Changsha University of Science&Technology(No.CX2017SS25)+1 种基金the Scientific Research Fund of Hunan Provincial Education Department(No.15C0034)the Introduction of Talents Project of Changsha University of Science Technology(No.1198023)
文摘An ultralow specific on-resistance high-k LDMOS with vertical field plate（VFP HK LDMOS） is proposed. The high-k dielectric trench and highly doped interface N＋ layer are made in bulk silicon to reduce the surface field of the drift region in the VFP HK LDMOS. The gate vertical field plate（VFP） pinning in the high-k dielectric trench can modulate the bulk electric field. The high-k dielectric not only provides polarized charges to assist depletion of the drift region, so that the drift region and high-k trench maintain charge balance adaptively,but also can fully assist in depleting the drift region to increase the drift doping concentration and reshape the electric field to avoid premature breakdown. Compared with the conventional structure, the VFP HK LDMOS has the breakdown voltage of 629.1 V at the drift length of 40 μm and the specific on-resistance of 38.4 mΩ·cm^2 at the gate potential of 15 V. Then the power figure of merit is 10.31 MW/cm^2.
