A pre-ohmic micro-patterned recess process,is utilized to fabricate Ti/Al/Ti/TiN ohmic contact to an ultrathin-barrier(UTB)AlGaN/GaN heterostructure,featuring a significantly reduced ohmic contact resistivity of 0.56...A pre-ohmic micro-patterned recess process,is utilized to fabricate Ti/Al/Ti/TiN ohmic contact to an ultrathin-barrier(UTB)AlGaN/GaN heterostructure,featuring a significantly reduced ohmic contact resistivity of 0.56Ω·mm at an alloy temperature of 550℃.The sheet resistances increase with the temperature following a power law with the index of +2.58,while the specific contact resistivity decreases with the temperature.The contact mechanism can be well described by thermionic field emission(TFE).The extracted Schottky barrier height and electron concentration are 0.31 eV and 5.52×10^(18) cm^(−3),which suggests an intimate contact between ohmic metal and the UTB-AlGaN as well as GaN buffer.A good correlation between ohmic transfer length and the micro-pattern size is revealed,though in-depth investigation is needed.A preliminary CMOS-process-compatible metal-insulator-semiconductor high-mobility transistor(MIS-HEMT)was fabricated with the proposed Au-free ohmic contact technique.展开更多
One of the key technology enablers for achieving three-dimensional(3D)Dynamic Random Access Memory is the development of dielectric materials with high permittivity,low leakage current,and a low thermal budget.In this...One of the key technology enablers for achieving three-dimensional(3D)Dynamic Random Access Memory is the development of dielectric materials with high permittivity,low leakage current,and a low thermal budget.In this work,theoretical analysis reveals that a substitutional doping configuration is crucial to enable the realization of a morphotropic phase boundary(MPB)and low thermal budget.Guided by this,we present the fabrication of a La-doped Hf_(0.5)Zr_(0.5)O_(2)(HZO)dielectric with a recordhigh permittivity of~83 at a low thermal budget(~450°C).The film has a physical thickness of 10 nm(EOT=0.46 nm)and demonstrates a low leakage current of 1E-6 A/cm^(2)at 1 V.Reliability assessments suggest that our films can be stable up to 2.25 V with a 0.01%failure rate and a dielectric area of 0.1 cm2 for over 10 years.The successful development of this dielectric establishes a strong foundation for future transistors,memories,and their 3D integration.展开更多
This paper is devoted to the features of sea-surface heat budget during the active/break phases of the 2000 summer monsoon in the South-China Sea (SCS) by means of the observed air-sea heat fluxes and data from Xisha ...This paper is devoted to the features of sea-surface heat budget during the active/break phases of the 2000 summer monsoon in the South-China Sea (SCS) by means of the observed air-sea heat fluxes and data from Xisha Weather Station and NCEP/NCAR in the same period.Results suggest that the primary factors affecting sea-surface thermal budget are solar shortwave penetrating radiation and latent heat flux.Regardless of their changes,however,the thermal gain is reduced or becomes net loss at the active stage and the thermal gain gets gradually increased in the weakening and lull periods:during the first emergence of southwest monsoon the net loss happens thanks to the dramatic diminution of penetrating radiation resulting from increased cloudiness and intense precipitation:while at the re-emergence of the wind.reduced net sea-surface thermal gain is attributed to the sharp increase in latent heat flux resulting from intense evaporation:owing to great thermal inertia of water the SST change lags behind that of heat budget over the sea surface, and the lagging is responsible for regulating the budget by affecting latent heat fluxes,which,in turn.has effect upon the change of the SST,thereby forming short-term oscillations that are in association with the active/break phases of the monsoons.Part of the conclusions have been borne out by the observational study based on 1998 and 2002 data.展开更多
Sub-20 nm node bulk FinFET PMOS devices with an all-last high-k/metal gate （HK/MG） process are fabricated and the influence of a series of device parameters on the device scaling is investigated. The high and thin F...Sub-20 nm node bulk FinFET PMOS devices with an all-last high-k/metal gate （HK/MG） process are fabricated and the influence of a series of device parameters on the device scaling is investigated. The high and thin Fin structure with a tapered sidewall shows better performance than the normal Fin structure. The punch through stop layer （PTSL） and source drain extension （SDE） doping profiles are carefully optimized. The device without SDE annealing shows a larger drive current than that with SDE annealing due to better Si crystal regrowth in the amorphous Fin structure after source/drain implantation. The band-edged MG has a better short channel effect immunity, but the lower effective work function （EWF） MG shows a larger driveability. A tradeoff choice for different EWF MGs should be carefully designed for the device＇s scaling.展开更多
In this work,thick BiFeO_(3)films(~1μm)were prepared on LaNiO_(3)-buffered(111)Pt/Ti/SiO_(2)/(100)Si substrates via radio-frequency magnetron sputtering without post-growth annealing.The effects of the substrate temp...In this work,thick BiFeO_(3)films(~1μm)were prepared on LaNiO_(3)-buffered(111)Pt/Ti/SiO_(2)/(100)Si substrates via radio-frequency magnetron sputtering without post-growth annealing.The effects of the substrate temperature on the film’s crystallinity,defect chemistry,and associated electrical properties were investigated.In contrast to the poorly crystallized BiFeO_(3)film deposited at 300℃and the randomly-oriented and(111)-textured films deposited at 500 and 650℃,respectively,a(001)-preferred orientation was achieved in the BiFeO_(3)film deposited at 350℃.This film not only showed a dense,fine-grained morphology but also displayed enhanced electrical properties due to the(001)texture and improved defect chemistry.These properties include a reduced leakage current(J≈2.4×10^(−5)A/cm^(2)@200 kV/cm),a small dielectric constant(ε_(r)≈243–217)with a low loss(tanδ≤0.086)measured from 100 Hz to 1 MHz,and a nearly intrinsic remnant polarization(Pr)of~60μC/cm^(2).A detailed TEM analysis confirmed the R3c symmetry of the BFO films and hence ensured good stability of their electrical properties.In particular,single-beam cantilevers fabricated from BiFeO_(3)/LaNiO_(3)/Pt/Ti/SiO_(2)/Si heterostructures showed excellent electromechanical performance,including a large transverse piezoelectric coefficient(e_(31,f))of~−2.8 C/m^(2),a high figure of merit(FOM)parameter of~4.0 GPa,and a large signal-to-noise ratio of~1.5 C/m^(2).An in-depth analysis revealed the intrinsic nature of the e_(31,f)piezoelectric coefficient,which is well fitted along a straight line of e_(31,f)ratio=(ε_(r)P_(r))ratio with the reported representative results.These high-quality lead-free piezoelectric films processed with a reduced thermal budget can open many possibilities for the integration of piezoelectricity into Si-based microelectro–mechanical systems(MEMSs).展开更多
基金supported by National Natural Science Foundation of China under Grant 61822407,Grant 62074161,and Grant 11634002in part by the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS)under Grant QYZDB-SSW-JSC012+3 种基金in part by the National Key Research and Development Program of China under Grant 2016YFB0400105 and Grant 2017YFB0403000in part by the Youth Innovation Promotion Association of CASin part by the University of Chinese Academy of Sciencesand in part by the Opening Project of Key Laboratory of Microelectronic Devices&Integrated Technology,Institute of Microelectronics,CAS.
文摘A pre-ohmic micro-patterned recess process,is utilized to fabricate Ti/Al/Ti/TiN ohmic contact to an ultrathin-barrier(UTB)AlGaN/GaN heterostructure,featuring a significantly reduced ohmic contact resistivity of 0.56Ω·mm at an alloy temperature of 550℃.The sheet resistances increase with the temperature following a power law with the index of +2.58,while the specific contact resistivity decreases with the temperature.The contact mechanism can be well described by thermionic field emission(TFE).The extracted Schottky barrier height and electron concentration are 0.31 eV and 5.52×10^(18) cm^(−3),which suggests an intimate contact between ohmic metal and the UTB-AlGaN as well as GaN buffer.A good correlation between ohmic transfer length and the micro-pattern size is revealed,though in-depth investigation is needed.A preliminary CMOS-process-compatible metal-insulator-semiconductor high-mobility transistor(MIS-HEMT)was fabricated with the proposed Au-free ohmic contact technique.
基金supported by the National Natural Science Foundation of China(Nos.62304136,62027818,61874034,11974320,T2293704 and T2293700)Startup Fund for Young Faculty at SJTU(24X010502924)National Key Research and Development Program of China under Grant 2023YFB4402204.
文摘One of the key technology enablers for achieving three-dimensional(3D)Dynamic Random Access Memory is the development of dielectric materials with high permittivity,low leakage current,and a low thermal budget.In this work,theoretical analysis reveals that a substitutional doping configuration is crucial to enable the realization of a morphotropic phase boundary(MPB)and low thermal budget.Guided by this,we present the fabrication of a La-doped Hf_(0.5)Zr_(0.5)O_(2)(HZO)dielectric with a recordhigh permittivity of~83 at a low thermal budget(~450°C).The film has a physical thickness of 10 nm(EOT=0.46 nm)and demonstrates a low leakage current of 1E-6 A/cm^(2)at 1 V.Reliability assessments suggest that our films can be stable up to 2.25 V with a 0.01%failure rate and a dielectric area of 0.1 cm2 for over 10 years.The successful development of this dielectric establishes a strong foundation for future transistors,memories,and their 3D integration.
基金the NSFC (National Natural Science Foundation of China) key program (No.40136010)the NSFC programs (No.40075003 and No.90211010)
文摘This paper is devoted to the features of sea-surface heat budget during the active/break phases of the 2000 summer monsoon in the South-China Sea (SCS) by means of the observed air-sea heat fluxes and data from Xisha Weather Station and NCEP/NCAR in the same period.Results suggest that the primary factors affecting sea-surface thermal budget are solar shortwave penetrating radiation and latent heat flux.Regardless of their changes,however,the thermal gain is reduced or becomes net loss at the active stage and the thermal gain gets gradually increased in the weakening and lull periods:during the first emergence of southwest monsoon the net loss happens thanks to the dramatic diminution of penetrating radiation resulting from increased cloudiness and intense precipitation:while at the re-emergence of the wind.reduced net sea-surface thermal gain is attributed to the sharp increase in latent heat flux resulting from intense evaporation:owing to great thermal inertia of water the SST change lags behind that of heat budget over the sea surface, and the lagging is responsible for regulating the budget by affecting latent heat fluxes,which,in turn.has effect upon the change of the SST,thereby forming short-term oscillations that are in association with the active/break phases of the monsoons.Part of the conclusions have been borne out by the observational study based on 1998 and 2002 data.
基金supported by the National 02 IC Projectsthe Opening Project of Key Laboratory of Microelectronics Devices & Integrated Technology,Institute of Microelectronics,Chinese Academy of Sciences
文摘Sub-20 nm node bulk FinFET PMOS devices with an all-last high-k/metal gate （HK/MG） process are fabricated and the influence of a series of device parameters on the device scaling is investigated. The high and thin Fin structure with a tapered sidewall shows better performance than the normal Fin structure. The punch through stop layer （PTSL） and source drain extension （SDE） doping profiles are carefully optimized. The device without SDE annealing shows a larger drive current than that with SDE annealing due to better Si crystal regrowth in the amorphous Fin structure after source/drain implantation. The band-edged MG has a better short channel effect immunity, but the lower effective work function （EWF） MG shows a larger driveability. A tradeoff choice for different EWF MGs should be carefully designed for the device＇s scaling.
基金funding support from the National Natural Science Foundation of China(Nos.52002192,51772175,and 52402149)the Natural Science Foundation of Shandong Province(Nos.ZR2020QE042,ZR2022ZD39,ZR2022QB138,and ZR2022ME031)+4 种基金Hanfei Zhu and Qingguo Chi are grateful for the support from the Key Laboratory of Engineering Dielectrics and Its Application(Harbin University of Science and Technology),Ministry of Education(No.KFM202404)Jun Ouyang and Isaku Kanno acknowledge the financial support from the“Double Hundred Talent Plan”(No.WSG2021031)from Shandong Province,ChinaJun Ouyang is also grateful for the funding support from the Jinan City Science and Technology Bureau(No.2021GXRC055)the Education Department of Hunan Province/Xiangtan University(No.KZ0807969)the Top Talents of Qilu University of Technology(Shandong Academy of Sciences).
文摘In this work,thick BiFeO_(3)films(~1μm)were prepared on LaNiO_(3)-buffered(111)Pt/Ti/SiO_(2)/(100)Si substrates via radio-frequency magnetron sputtering without post-growth annealing.The effects of the substrate temperature on the film’s crystallinity,defect chemistry,and associated electrical properties were investigated.In contrast to the poorly crystallized BiFeO_(3)film deposited at 300℃and the randomly-oriented and(111)-textured films deposited at 500 and 650℃,respectively,a(001)-preferred orientation was achieved in the BiFeO_(3)film deposited at 350℃.This film not only showed a dense,fine-grained morphology but also displayed enhanced electrical properties due to the(001)texture and improved defect chemistry.These properties include a reduced leakage current(J≈2.4×10^(−5)A/cm^(2)@200 kV/cm),a small dielectric constant(ε_(r)≈243–217)with a low loss(tanδ≤0.086)measured from 100 Hz to 1 MHz,and a nearly intrinsic remnant polarization(Pr)of~60μC/cm^(2).A detailed TEM analysis confirmed the R3c symmetry of the BFO films and hence ensured good stability of their electrical properties.In particular,single-beam cantilevers fabricated from BiFeO_(3)/LaNiO_(3)/Pt/Ti/SiO_(2)/Si heterostructures showed excellent electromechanical performance,including a large transverse piezoelectric coefficient(e_(31,f))of~−2.8 C/m^(2),a high figure of merit(FOM)parameter of~4.0 GPa,and a large signal-to-noise ratio of~1.5 C/m^(2).An in-depth analysis revealed the intrinsic nature of the e_(31,f)piezoelectric coefficient,which is well fitted along a straight line of e_(31,f)ratio=(ε_(r)P_(r))ratio with the reported representative results.These high-quality lead-free piezoelectric films processed with a reduced thermal budget can open many possibilities for the integration of piezoelectricity into Si-based microelectro–mechanical systems(MEMSs).
