共查询到20条相似文献,搜索用时 109 毫秒
1.
Xiliang He Xiaomin Li Xiangdong Gao Weidong Yu Rui Yang Xinjun Liu Xun Cao 《Applied Physics A: Materials Science & Processing》2012,108(1):177-183
Unipolar reversible resistance switching effects were found in 5 at% Ti-doped polycrystalline Ta2O5 films with the device structure of Pt/Ti–Ta2O5/Pt. Results suggest that the recovery/rupture of the conductive filaments which are involved in the participation of oxygen vacancies and electrons leads to the resistance switching process. Ti-doped Ta2O5 thin films possess higher resistance whether in low-resistance state or high-resistance state and higher resistance switching ratio than Ta2O5 thin films, where Ti addition plays an important role in the resistance switching process by suppressing the migration of oxygen vacancies via forming an electrically inactive Ti/O–vacancy complex. Excellent retention properties of the high and low resistances under constant stress of applied voltage were obtained. 相似文献
2.
D. Spassov E. Atanassova D. Virovska 《Applied Physics A: Materials Science & Processing》2006,82(1):55-62
Al, W and TiN gate stacks using reactively sputtered thin (15–35 nm) Ta2O5 as a high-k dielectric have been investigated. It has been established that the type and the deposition technique of the gate electrode strongly affect the parameters of the structures. RF sputtered tungsten has been established as the most suitable electrode material (giving a nonreactive contact) providing a low leakage current (∼10-8 A/cm2 at 1 MV/cm) through capacitors and a high dielectric constant. The application of Al gate electrodes in the advanced DRAM devices is impeded by the chemical interaction of Al with the Ta2O5 films deteriorating the performance of the structures. The radiation-induced defects during the TiN deposition increase the leakage currents for TiN/Ta2O5/Si capacitors. A modified Poole–Frenkel conduction mechanism with a tendency for a reduction of the compensation level with increasing Ta2O5 thickness was found for W-gate capacitors. Schottky emission at low applied fields and modified Poole–Frenkel mechanism at high fields define the J–V characteristics of Al capacitors. The current through TiN capacitors is governed by ohmic and space charge limited conduction. The post metallization annealing in H2 reduces the oxide charge but deteriorates both the breakdown fields and the leakage currents for all capacitors studied. The effect is stronger for Al and TiN structures and is accompanied by a reduction of the dielectric constant. PACS 72.80.Sk; 73.40.Qv; 77.55+f; 81.15 Cd 相似文献
3.
Yun Hoe Kim Jong-Han SongJin Sang Kim Seok-Jin YoonKyung Bong Park Ji-Won Choi 《Applied Surface Science》2011,258(2):843-847
The dielectric properties of MgO-Ta2O5 continuous composition spread (CCS) thin films were investigated. The MgO-Ta2O5 CCS thin films were deposited on Pt/Ti/SiO2/Si substrates by off-Axis RF magnetron sputtering system, and then the films were annealed at 350 °C with rapid thermal annealing system in vacuum. The dielectric constant and loss of MgO-Ta2O5 CCS thin films were plotted via 1500 micron-step measuring. The specific point of Ta2O5-MgO CCS thin film (post annealed at 350 °C) showing superior dielectric properties of high dielectric constant (k ∼ 28) and low dielectric loss (tan δ < 0⋅004) at 1 MHz were found in the area of 3-5 mm apart from Ta2O5 side on the substrate. The cation's composition of thin film was Mg:Ta = 0.4:2 at%. 相似文献
4.
A. Paskaleva M. ?apajna E. Dobro?kaK. Hušeková E. AtanassovaK. Fröhlich 《Applied Surface Science》2011,257(17):7876-7880
Hf-doped Ta2O5 thin films are studied with respect to their composition, dielectric and electrical properties. The incorporation of Hf is performed by sputtering of a 0.7 nm thick Hf layer on top of Ta2O5 and subsequent annealing to stimulate diffusion of Hf into Ta2O5 and their intermixing. The elemental in-depth distribution of the films is investigated by the time of flight secondary ion mass spectroscopy (ToF-SIMS), which has revealed that Hf and Ta2O5 are intermixed throughout the whole thickness. Two sub-layers exist in all the samples - an upper homogeneous Hf-doped Ta2O5 sub-layer and a near interfacial region which is a mixture of Ta- and Si-oxides. The X-ray reflectivity (XRR) analysis shows existence of interfacial layer with a thickness of about 1.9-2 nm, irrespectively of the total thickness of the stacks. Metal-oxide-Si structures with Ru and RuO2 metal electrodes have been prepared and investigated in terms of dielectric constant, effective work function (EWF) and interfacial layer parameters. The influence of post-metallization annealing steps on these parameters was also studied. 相似文献
5.
The electrical (C-V and I-V) and reliability (constant current stress technique) properties of RF sputtered 30 nm thick Ta2O5 on N-implanted Si have been investigated. The dependence on the parameters of both Ta2O5 and the implanted interfacial layers on the stress time are discussed. The leakage current characteristics are analyzed by previously proposed comprehensive model. It is established that the reliability of the Ta2O5-based capacitors can be effectively improved if the Si substrate is a subject to preliminary N-implantation—markedly smaller stress induced leakage current as compared to the films on bare Si are detected. The stress mainly affects the properties of the interfacial layer and the generation of neutral traps is identified to be the primary cause for the stress-induced degradation. It is concluded that the implantation results in a strengthening of the interfacial layer against stress degradation. 相似文献
6.
The effects of vanadium(V) doping into SrBi4Ti4O15 (SBTi) thin films on the structure, ferroelectric, leakage current, dielectric, and fatigue properties have been studied. X-ray diffraction result showed that the crystal structure of the SBTi thin films with and without vanadium is the same. Enhanced ferroelectricity was observed in the V-doped SrBi4Ti4O15 (SrBi4−x/3Ti4−xVxO15, SBTiV-x (x = 0.03, 0.06, and 0.09)) thin films compared to the pure SrBi4Ti4O15 thin film. The values of remnant polarization (2Pr) and coercive field (2Ec) of the SBTiV-0.09 thin film capacitor were 40.9 μC/cm2 and 105.6 kV/cm at an applied electric field of 187.5 kV/cm, respectively. The 2Pr value is over five times larger than that of the pure SBTi thin film capacitor. At 100 kHz, the values of dielectric constant and dielectric loss were 449 and 0.04, and 214 and 0.06 for the SBTiV-0.09 and the pure SBTi thin film capacitors, respectively. The leakage current density of the SBTiV-0.09 thin film capacitor measured at 100 kV/cm was 6.8 × 10−9 A/cm2, which is more than two and a half orders of magnitude lower than that of the pure SBTi thin film capacitor. Furthermore, the SBTiV-0.09 thin film exhibited good fatigue endurance up to 1010 switching cycles. The improved electrical properties may be related to the reduction of internal defects such as bismuth and oxygen vacancies with changes in the grain size by doping of vanadium into SBTi. 相似文献
7.
用溶胶-凝胶方法在Pt/Ti/SiO2/Si衬底上制备了Na+的不同浓度均匀掺杂和成分梯度掺杂(上梯度)钛酸锶钡(Ba0.25Sr0.75TiO3)薄膜.电性能测试表明随着均匀掺杂浓度的增加,薄膜介电常数和损耗都减小,而漏电流先减小(掺杂浓度小于2.5mol%时)后又逐渐增加.场发射扫描电镜分析表明,均匀掺杂浓度增加到2.5mol%后薄膜表面呈疏松多孔状结构,这可能是导致漏电流又逐渐增大的原因.Na+的上梯度掺杂避免了掺杂浓度增加到2.5mol%后薄膜生长过程中出现的孔洞现象,于是薄膜的综合电性能得到了进一步提高.深入、系统地分析了杂质不同分布方式对薄膜结构和性能有不同影响的原因. 相似文献
8.
Jong-Ho ParkChung-Sik Kim Byung-Chun Choi Jung-Hyun JeongByung Kee Moon Hyo-Jin SeoIll-Won Kim Jin-Soo Kim 《Solid State Communications》2003,127(4):315-318
The dependence of the electrical properties of SrxBiyTa2O9 thin films on the (Bi/Sr ratio 1.6, 2.3, 2.8, 3.4) has been investigated. The SrxBiyTa2O9 ferroelectric thin films were synthesized on Pt/Ti/SiO2/Si substrates using the pulsed laser deposition method. Saturation polarization (Pst) and coercive field (2Ec) depend on the Bi/Sr ratio. Pst increases while Ec decreases with an increase in Bi/Sr ratio. Atomic Force Microscopy images show that the grain size grows with increasing Bi/Sr ratio. It is observed that the impedance behavior in SrxBiyTa2O9 thin film, conforms to the Constant Phase Element (CPE) model. It is believed that the diffuse charges at the grain boundary build up a surface polarization because the impedance behavior close to pure capacitor with grain size increased. 相似文献
9.
Dielectric-breakdown-like forming process in the unipolar resistance switching of Ta2O5−x thin films
Moon Jee YoonShin Buhm Lee Hyang Keun YooSoobin Sinn Bo Soo Kang 《Current Applied Physics》2012,12(3):846-848
We report unipolar resistance switching (URS) in Ta2O5−x thin films. The current increased suddenly when we applied voltages up to 5-7 V to the pristine state of Pt/Ta2O5−x/Pt, Ni/Ta2O5−x/Pt, and Ti/Ta2O5−x/Pt cells. Just after this forming process, we observed a repetitive URS occurring independently of the electrodes. We found that the required voltages for the forming process did not depend on the top electrode type, but on the film thickness. These results suggest that the forming process is driven by a dielectric-breakdown-like phenomenon, and that URS occurs due to the formation and rupture of conducting channels inside the Ta2O5−x thin film. 相似文献
10.
V. M. Kalygina A. T. Zyryanov V. A. Novikov Yu. S. Petrova M. S. Skakunov O. P. Tolbanov A. V. Tyazhev T. M. Yaskevich 《Russian Physics Journal》2011,53(12):1312-1317
The effect of substrate material on the electrical characteristics of Ta
x
O
y
films produced by high-frequency magnetron sputtering of a tantalum oxide target is studied. The effect of oxygen plasma
on leakage currents, dielectric permittivity, and dielectric dissipation factor of thin (300–400 nm) Ta
x
O
y
layers is found. It is proposed to process tantalum oxide films in oxygen plasma to control their electrical and dielectric
properties. 相似文献
11.
Effects of O2/Ar ratio and annealing temperature on electrical properties of Ta2O5 film prepared by magnetron sputtering
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The effects of the oxygen-argon ratio on electric properties of Ta2O5 film prepared by radio-frequency magnetron sputtering were investigated.The Ta2O5 partially transforms from the amorphous phase into the crystal phase when annealing temperatures are 800℃ or higher.The lattice constant of Ta2O5 decreases with the increase of the O2/Ar ratio,which indicates that oxygen gas in the working gas mixture contributes to reducing the density of oxygen vacancies during the deposition process.For the films deposited in working gas mixtures with different O2/Ar ratios and subsequently annealed at 700℃,the effective dielectric constant is increased from 14.7 to 18.4 with the increase of the O2/Ar ratio from 0 to 1.Considering the presence of an SiO2 layer between the film and the silicon substrate,the optimal dielectric constant of Ta2O5 film was estimated to be 31.Oxygen gas in the working gas mixture contributes to reducing the density of oxygen vacancies,and the oxygen vacancy density and leakage current of Ta2O5 film both decrease with the increase of the O2/Ar ratio.The leakage current decreases after annealing treatment and it is minimized at 700℃.However,when the annealing temperature is 800℃ or higher,it increases slightly,which results from the partially crystallized Ta2O5 layer containing defects such as grain boundaries and vacancies. 相似文献
12.
Thermo-Sensitive Ba0.64Sr0.36TiO3 Thin Film Capacitors for Dielectric Type Uncooled Infrared Sensors
Liang Dong Ruifeng Yue Litian Liu Xiaoning Wang Jianshe Liu Tianling Ren 《International Journal of Infrared and Millimeter Waves》2003,24(8):1341-1349
Ba0.64Sr0.36TiO3 (BST) thin films are prepared on Pt/Ti/SiO2/Si3N4/SiO2/Si substrates by a sol-gel method. Thermo-sensitive BST thin film capacitors with a Metal-Ferroelectrics-Metal (M-F(BST)-M) structure are fabricated as the active elements of dielectric type uncooled infrared sensors. XRD are employed to analyze the crystallographic structures of the films. AFM observations reveal a smooth and dense surface of the films with an average grain size of about 35 nm. Rapid temperature annealing (RTA) process is a very efficient way to improve crystallization quality. The preferable annealing temperature is 800°C for 1 min. The butterfly shaped C-V curves of the capacitors indicate the films have a ferroelectric nature. The dielectric constant and dielectric loss of the films at 100 kHz are 450 and 0.038, respectively. At 25°C, where the thermo-sensitive capacitors work, the temperature coefficient of dielectric constant (TCD) is about 5.9 %/°C. These results indicate that the capacitors with sol-gel derived BST thin films are promising to develop dielectric type uncooled infrared sensors. 相似文献
13.
Sandwich-structure Al2O3/HfO2/Al2O3 gate dielectric films were grown on ultra-thin silicon-on-insulator (SOI) substrates by vacuum electron beam evaporation (EB-PVD) method. AFM and TEM observations showed that the films remained amorphous even after post-annealing treatment at 950 °C with smooth surface and clean silicon interface. EDX- and XPS-analysis results revealed no silicate or silicide at the silicon interface. The equivalent oxide thickness was 3 nm and the dielectric constant was around 7.2, as determined by electrical measurements. A fixed charge density of 3 × 1010 cm−2 and a leakage current of 5 × 10−7A/cm2 at 2 V gate bias were achieved for Au/gate stack /Si/SiO2/Si/Au MIS capacitors. Post-annealing treatment was found to effectively reduce trap density, but increase in annealing temperature did not made any significant difference in the electrical performance. 相似文献
14.
Ba0.70Sr0.30TiO3 (BST) thin films doped by Co (BSTC) are fabricated by sol-gel method on a Pt/Ti/SiO2/Si substrate. A strong correlation is observed among the microstructure, dielectric, ferroelectric, ferromagnetic properties and Co concentration. The dielectric constant of BST thin films can be tailored from 343 to 119 by manipulating the Co concentration. The dielectric loss of BSTC thin films are still kept below 0.020 and the tunability is above 30% at a dc-applied electric field of 500 kV/cm. With increasing Co doping up to 10 mol%, the coexistence of ferromagnetism and ferroelectrics is found. Suitable dielectric constant, low-dielectric loss, and high tunability of this kind of thin films can be useful for potential tunable applications. 相似文献
15.
The CaCu3Ti4O12/SiO2/CaCu3Ti4O12 (CCTO/SiO2/CCTO) multilayered films were prepared on Pt/Ti/SiO2/Si substrates by pulsed laser deposition method. It has been demonstrated that the dielectric loss and the leakage current density were significantly reduced with the increase of the SiO2 layer thickness, accompanied with a decrease of the dielectric constant. The CCTO film with a 20 nm SiO2 layer showed a dielectric loss of 0.065 at 100 kHz and the leakage current density of 6×10−7 A/cm2 at 100 kV/cm, which were much lower than those of the single layer CCTO films. The improvement of the electric properties is ascribed to two reasons: one is the improved crystallinity; the other is the reduced free carriers in the multilayered films. 相似文献
16.
Q. Simon V. Bouquet V. Demange S. Députier F. WycziskG. Garry A. ZiaieM. Guilloux-Viry 《Applied Surface Science》2011,257(22):9485-9489
The diffusion of Mg in pulsed laser deposited K(Ta0.65Nb0.35)O3 thin films epitaxially grown on (1 0 0) MgO single crystal substrate were investigated by Auger electron spectroscopy (AES). A diffusion of Mg from the substrate into the whole thickness (400 nm) of the as-deposited K(Ta0.65Nb0.35)O3 films was observed with an accumulation of Mg at the surface. Ex situ post-annealing (750 °C/2 h) has led to a homogeneous distribution of Mg in all the ferroelectric coating. This strong reaction between film and substrate promotes a doping effect, responsible for the reduction of K(Ta0.65Nb0.35)O3 dielectric losses in comparison with films grown on other substrates. 相似文献
17.
Jun Liu Meiya Li Zhongqiang Hu Ling Pei Jing Wang Xiaolian Liu Xingzhong Zhao 《Applied Physics A: Materials Science & Processing》2011,102(3):713-717
A-site Ce and B-site Zr codoped Bi1−x
Ce
x
Fe1−y
Zr
y
O3 (BCFZ) thin films with different compositions were successfully prepared on the Pt/Ti/SiO2/Si substrates by chemical solution deposition. The influence of the A-site Ce and B-site Zr codoping on the structure, surface
morphology, electrical and magnetic properties of BFO films were investigated, respectively. The comparative study suggested
that the A-site Ce doping with various contents have notable influences on the electrical properties of the BFO films, while
the B-site Zr doping with different contents affect mainly the magnetic properties of the BFO films. Compared with the other
BCFZ films studied here, the Bi0.97Ce0.03Fe0.97Zr0.03O3 film showed the lowest dielectric loss and leakage current density, a well-squared P–E loop and fatigue-free characteristics as well as the strong magnetization. 相似文献
18.
Hongwei Chen Chuanren Yang Jihua Zhang Bo Wang Hong Ji 《Applied Surface Science》2009,255(8):4585-4589
BaZr0.1Ti0.9O3 and BaZr0.2Ti0.8O3 (BZT) thin films were deposited on Pt/Ti/LaAlO3 (1 0 0) substrates by radio-frequency magnetron sputtering, respectively. The films were further annealed at 800 °C for 30 min in oxygen. X-ray diffraction θ-2θ and Φ-scans showed that BaZr0.1Ti0.9O3 films displayed a highly (h 0 0) preferred orientation and a good cube-on-cube epitaxial growth on the LaAlO3 (1 0 0) substrate, while there are no obvious preferential orientation in BaZr0.2Ti0.8O3 thin films. The BaZr0.1Ti0.9O3 films possess larger grain size, higher dielectric constant, larger tunability, larger remanent polarization and coercive electric field than that of BaZr0.2Ti0.8O3 films. Whereas, BaZr0.1Ti0.9O3 films have larger dielectric losses and leakage current density. The results suggest that Zr4+ ion can decrease dielectric constant and restrain non-linearity. Moreover, the enhancement in dielectric properties of BaZr0.1Ti0.9O3 films may be attributed to (1 0 0) preferred orientation. 相似文献
19.
The effect of a small amount Fe2O3 (0.1-2 mol%) doping on the electrical properties of (Na0.5K0.5)0.96Li0.04Nb0.86Ta0.1Sb0.04O3 (NKLNTS) ceramics was investigated. It was found that the B-site substitution of Fe3+ does not change the crystal structure within the studied doping level and all modified ceramics have a pure tetragonal perovskite structure at room temperature. The addition of Fe2O3 can promote the sintering of NKLNTS ceramics, and simultaneously cause the grain growth so that Fe3+-doped NKLNTS compositions show degraded densification at higher doping level. Furthermore, the dielectric properties of the NKLNTS ceramics do not show a significant change by Fe2O3 doping. However, the addition of Fe2O3 was found to have a significant influence on the electric fatigue resistance and the durability against water. The presence of oxygen vacancies caused by the replacement of Fe3+ for B-site ions makes the NKLNTS ceramics harder. 相似文献
20.
Density functional theory study of NO2-sensing mechanisms of pure and Ti-dopedWO3 (002) surfaces
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Density functional theory (DFT) calculations are employed to explore the NO2-sensing mechanisms of pure and Ti-doped WO3 (002) surfaces. When Ti is doped into the WO3 surface, two substitution models are considered: substitution of Ti for W6c and substitution of Ti for W5c. The results reveal that substitution of Ti for 5-fold W forms a stable doping structure, and doping induces some new electronic states in the band gap, which may lead to changes in the surface properties. Four top adsorption models of NO2 on pure and Ti-doped WO3 (002) surfaces are investigated: adsorptions on 5-fold W (Ti), on 6-fold W, on bridging oxygen, and on plane oxygen. The most stable and likely NO2 adsorption structures are both N-end oriented to the surface bridge oxygen O1c site. By comparing the adsorption energy and the electronic population, it is found that Ti doping can enhance the adsorption of NO2, which theoretically proves the experimental observation that Ti doping can greatly increase the WO3 gas sensor sensitivity to NO2 gas. 相似文献