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1.
Highly (100)-oriented, compositionally graded (Pb,Ca)TiO3 (PCT) thin films with a Ca content from 0 to 24 mol% on Pt/Ti/SiO2/Si substrates were prepared by a sol-gel process. The graded structure of the Au/PCT/Pt film capacitor showed a well-saturated hysteresis loop at an applied field of 500 kV/cm with remanent polarization (Pr), and coercive electric field (Ec) values of 9.35 C/cm2 and 130 kV/cm, respectively. At 100 kHz, the dielectric constant and dielectric loss of the film were 129 and 0.024, respectively. The leakage current density of the graded PCT film was less than 1.0×10-7 A/cm2 over a voltage range from 0 to 4 V. The conduction current depended on the voltage polarity. At low electric field (110 and 180 kV/cm, respectively, for Pt and Au electrodes biased negatively), the Au/PCT and PCT/Pt interfaces form a Schottky barrier. At high electric field (>110 kV/cm), the Au electrode biased negatively shows space-charge-limited current (SCLC) behavior. The temperature dependencies of the pyroelectric coefficients of the graded PCT film were measured by a dynamic technique. From 20 to 82 °C, the pyroelectric coefficients of graded PCT film remain steady in the range 106 to 118 C/m2K. The detectivity figure of merit (FD) of the graded PCT film was 6.7×10-6 Pa-0.5. PACS 77.80.-s; 77.70.+a; 77.22.-d; 51.50.+v; 68.37.-d 相似文献
2.
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
3.
Y.H. Gao J.L. Sun J.H. Ma X.J. Meng J.H. Chu 《Applied Physics A: Materials Science & Processing》2008,91(3):541-544
(Ba,Sr)TiO3 (BST) capacitors grown on a LaNiO3 (LNO) bottom electrode, with Pt (80 nm), LNO (100 nm), and double-layer Pt/LNO (80/10 nm) top electrodes have been investigated.
It was found that the dielectric behavior is improved by a decrease of the electrical properties for the BST capacitor using
double-layer Pt/LNO top electrodes. The dielectric constant of 100 nm-thick BST films with a Pt electrode was only 165 at
100 kHz, while that with a double-layer electrode was about 242. Correspondingly, the tunability was greatly improved from
26% to 41% with an electric field of 600 kV/cm. These have been attributed to increased interfacial capacitance density, which
resulted from an improved interface, between the films and the top electrode. The dielectric loss was also reduced by using
a double-layer electrode. Furthermore, the leakage current of a capacitor with a double-layer Pt/LNO electrode was one order
of magnitude lower than that with a single LNO electrode. It can be explained by the fact that the weak chemical interaction
between LNO (10 nm) and BST causes a high potential barrier at the interface.
PACS 81.15.-z; 81.15.Cd; 77.55.+f; 77.84.Dy; 77.22.-d 相似文献
4.
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
5.
Xin-Gui Tang Jie Wang Xiao-Xing Wang Helen Lai-Wah Chan 《Solid State Communications》2004,130(6):373-377
Antiferroelectric PbZrO3 thin films were grown on Pt/Ti/SiO2/Si substrates with predominant (111) orientation using a sol-gel process. The Pt/PbZrO3/Pt film capacitor showed well-saturated hysteresis loops at an applied voltage of 5 V with remanent polarisation (Pr) and coercive electric field (Ec) values of 8.97 μC/cm2 and 162 kV/cm, respectively. The leakage current density of the highly (111)-oriented PbZrO3 film was less than 1.0×10−7 A/cm2 over electric field ranges from 0 to 105 kV/cm. The conduction current depended on the voltage polarity. The PbZrO3/Pt interface forms a Schottky barrier at electric fields from 20 to 160 kV/cm. The dielectric relaxation current behaviour of Pt/PbZrO3/Pt capacitor obeys the well-known Curie-Von Schweidler law at electric field of 20-80 kV/cm, the currents have contributions of both dielectric relaxation current and leakage current. 相似文献
6.
J.X. Liao C.R. Yang J.H. Zhang C.L. Fu H.W. Chen W.J. Leng 《Applied Surface Science》2006,252(20):7407-7414
Ba0.6Sr0.4TiO3 (BST) films were deposited on Pt/SiO2/Si substrates by radio frequency magnetron sputtering. The deposited films were crystallized by conventional thermal annealing (CTA) and rapid thermal annealing (RTA). The interfacial structures of BST/Pt were studied. High-resolution transmission electron microscopy (HRTEM) observation shows that there is a transition layer at BST/Pt interface, and the layer is 4-5 nm thick for CTA and 2-3 nm for RTA. X-ray photoelectron spectroscopy (XPS) investigations show that the layer is composed of perovskited BST phase and non-perovskited BST phase. The content of the non-perovskited BST phase is most for CTA, whereas that of the perovskited BST phase is most for RTA. It is found that the transition layer thickens with the increase of annealing temperature, and CTA corresponds to faster thickening rate. XPS shows that the non-perovskited BST phase does not come from the absorbed CO2 or CO contaminations, but from other interfacial elements. Also, it is indicated that the RTA-annealed BST film capacitor shows much better dielectric properties, with an average value of 150 higher dielectric constant and almost two orders of magnitude lower leakage current density than the CTA-annealed film capacitor. Grazing X-ray diffraction (GXRD) patterns exhibit that the RTA-annealed BST films present more compact structure. It is such a compact structure that can effectively prevent the absorbed elements further diffusing toward two sides, and cause thinner transition layer, thus result in higher dielectric constant and lower leakage current density. 相似文献
7.
8.
点接触金属/Pr$lt;sub$gt;0.7$lt;/sub$gt;Ca$lt;sub$gt;0.3$lt;/sub$gt;MnO$lt;sub$gt;3$lt;/sub$gt;/Pt结构稳定的低电流电阻开关特性
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利用自主开发的导电原子力显微镜控制Pt,W探针构成点接触金属/Pr0.7Ca0.3MnO3(PCMO)/Pt三明治结构,对其电流-电压(I-V)及脉冲诱导电阻开关(EPIR)特性进行了研究.研究发现,在10 nA限流下两种电极对应结构的I-V都表现出相当稳定的双极性电阻开关特性,以及大于100的电阻开关比.进一步测试发现,点接触W/PCMO/Pt器件具有在10 nA限流下稳定的EPIR特性以及100 pA限流下重复的双极性电阻开关特性.此电流比已报道的电流低3个数量级,表明此结构在低功耗存储器件方面的潜在应用.通过对比样品不同位置、不同限流、不同接触面积点接触Pt/PCMO/Pt的I-V回滞特性,把点接触器件在低电流下稳定、显著的电阻开关效应归结于小的器件面积导致强的局域电场加强了O离子迁移效应.
关键词:
脉冲诱导电阻开关
电场下氧离子迁移
电阻开关 相似文献
9.
AlGaN/GaN high electron mobility transistor (HEMT) based hydrogen sensors incorporating platinum nanonetworks in the gate region were demonstrated. Pt nanonetworks with 2–3 nm diameter were synthesized by a simple and low-cost solution phase method, and applied to the gate electrode of transistor sensor. The HEMT with physically and electrically connected Pt nanonetwork gate showed good pinch-off and modulation of drain current characteristics. Compared to conventional Pt thin film AlGaN/GaN HEMT sensor, the Pt nanonetwork sensor has dramatically improved current response to hydrogen. Relative current change of Pt nanonetwork gated sensor in 500 ppm H2 balanced with Air ambient was 3.3 × 106% at VGS of ?3.3 V, while 2.5 × 102% at VGS of ?2.9 V for Pt film. This results from large increase in channel conductance induced by huge catalytic surface area of nanostructured Pt networks. 相似文献
10.
Pb(Zr0.53Ti0.47)O3 (PZT) thin films with different thicknesses (99-420 nm) were prepared on Pt(1 1 1)/Ti/SiO2/Si(1 0 0) substrates by sol-gel method and films were annealed at 450 °C for 30 min using a single-mode cavity of 2.45 GHz microwaves. X-ray diffraction analysis indicated that the pyrochlore phase was transformed to the perovskite phase at above 166 nm films. The grain sizes were increased, surface roughnesses were decreased, and electrical properties were improved with film thickness. The leakage current density was 9 × 10−8 A/cm2 at an applied electrical field of 100 kV/cm. The ohmic and field-enhanced Schottky emission mechanisms were used to explain leakage current behavior of the PZT thin films. These results suggest that microwave annealing is effective for obtaining low temperature crystallization of thin films with better properties. 相似文献
11.
Gasidit Panomsuwan Osamu Takai Nagahiro Saito 《Applied Physics A: Materials Science & Processing》2012,108(2):337-342
Metal?Cferroelectric?Cinsulator?Csemiconductor (MFIS) structures with BaTiO3 (BTO) as a ferroelectric film and SrTiO3 (STO) as an insulating buffer layer were fabricated on p-type Si(001) substrates using an ion beam sputter deposition technique. The effect of out-of-plane orientation on the electrical properties of the MFIS structures, including leakage current density and memory window behavior, were studied using the growth of the BTO ferroelectric film on Si substrate buffered by highly c-axis-oriented and random-oriented STO buffer layers. The experimental results show that the out-of-plane orientations of the BTO films were almost identical to those of the STO buffer layers. The MFIS structure with a high c-axis orientation exhibited a maximum clockwise capacitance-voltage memory window of 1.17?V with a low leakage current of 1.05×10?7?A/cm2 at an applied voltage of 4?V, which is a significant improvement compared to the MFIS structure with a random orientation. The difference in the electrical properties of the MFIS structures with both types of orientation is discussed in detail. The results obtained from this study indicate that the Au/BTO/STO/p-Si MFIS structure with high c-axis orientation has good potential for use in non-volatile memory applications. 相似文献
12.
Z.H. Zhang X.L. Zhong H. Liao F. Wang J.B. Wang Y.C. Zhou 《Applied Surface Science》2011,257(17):7461-7465
In the present work, X-ray photoelectron spectroscopy (XPS) was used to investigate the composition depth profiles of Bi3.15Nd0.85Ti3O12 (BNT) ferroelectric thin film, which was prepared on Pt(1 1 1)/Ti/SiO2/Si(1 0 0) substrates by chemical solution deposition (CSD). It is shown that there are three distinct regions formed in BNT film, which are surface layer, bulk film and interface layer. The surface of film is found to consist of one outermost Bi-rich region. High resolution spectra of the O 1s peak in the surface can be decomposed into two components of metallic oxide oxygen and surface adsorbed oxygen. The distribution of component elements is nearly uniform within the bulk film. In the bulk film, high resolution XPS spectra of O 1s, Bi 4f, Nd 3d, Ti 2p are in agreement with the element chemical states of the BNT system. The interfacial layer is formed through the interdiffusion between the BNT film and Pt electrode. In addition, the Ar+-ion sputtering changes lots of Bi3+ ions into Bi0 due to weak Bi-O bond and high etching energy. 相似文献
13.
研究并比较了两种不同(Ba0.5,Sr0.5)TiO3(BSTO)薄膜介电-温度特性.采用脉冲激光沉积技术在Pt/Ti/SiO2/Si(100)衬底上制备BSTO薄膜,发现制备条件的不同,可以得到介电性质完全不同的BSTO薄膜.在550℃和氮气氛下制备的BSTO薄膜在常温下具有很高的介电常数,在10kHz下,超过2500,并在200K温度以上介电常数基本不变.它的一些电学性质不同于在正常条件(650℃和氧气氛下)制得的BSTO薄膜,而类似于目前广泛报道的巨介电常数材料如CaCu3Ti4O12.两种薄膜介电性质测试结果表明: 氧气氛下制备的BSTO薄膜呈现铁电-顺电相变,符合居里-外斯定律;低温氮气氛下制备的BSTO薄膜,介电弛豫时间和温度的关系符合德拜模型,是热激发弛豫.文中给出了产生这种介电特性的初步解释.
关键词:
薄膜
脉冲激光沉积
介电弛豫 相似文献
14.
L. Shi 《Applied Surface Science》2007,253(7):3731-3735
As a potential gate dielectric material, the La2O3 doped SiO2 (LSO, the mole ratio is about 1:5) films were fabricated on n-Si (0 0 1) substrates by using pulsed laser deposition technique. By virtue of several measurements, the microstructure and electrical properties of the LSO films were characterized. The LSO films keep the amorphous state up to a high annealing temperature of 800 °C. From HRTEM and XPS results, these La atoms of the LSO films do not react with silicon substrate to form any La-compound at interfacial layer. However, these O atoms of the LSO films diffuse from the film toward the silicon substrate so as to form a SiO2 interfacial layer. The thickness of SiO2 layer is only about two atomic layers. A possible explanation for interfacial reaction has been proposed. The scanning electron microscope image shows the surface of the amorphous LSO film very flat. The LSO film shows a dielectric constant of 12.8 at 1 MHz. For the LSO film with thickness of 3 nm, a small equivalent oxide thickness of 1.2 nm is obtained. The leakage current density of the LSO film is 1.54 × 10−4 A/cm2 at a gate bias voltage of 1 V. 相似文献
15.
Fengzhen Huang Xiaomei Lu Zhe Wang Weiwei Lin Yi Kan Huifeng Bo Wei Cai Jinsong Zhu 《Applied Physics A: Materials Science & Processing》2009,97(3):699-704
Multiferroic BiFeO3/Bi3.25La0.75Ti3O12 films annealed in different atmospheres (N2 or O2) were prepared on Pt/Ti/SiO2/Si substrates via a metal organic decomposition method. Based on our experimental results, it is considered that, in the
films annealed in N2, fewer Fe2+ ions while more oxygen vacancies are involved. As a result, at room temperature, predominated by the reduced Fe2+ fraction, lower leakage current and dielectric loss, better ferroelectric property while reduced magnetization are observed.
However, the oxygen vacancies might be thermally activated at elevated temperature; thus, more strongly temperature-dependent
leakage current and a higher dielectric relaxation peak are observed for the films annealed in N2. 相似文献
16.
Highly c-axis oriented neodymium-modified bismuth titanate (Bi4−xNdxTi3O12) films having a variety of neodymium (Nd) contents were successfully grown on Pt/TiO2/SiO2/Si(100) substrates using metal-organic sol decomposition. After systematically examining ferroelectric properties of the c-axis oriented Bi4−xNdxTi3O12 film capacitors as a function of the Nd-content, we concluded that the capacitor with x=0.85 had the largest remanent polarization. The Bi3.15Nd0.85Ti3O12 capacitor fabricated using a top Pt electrode showed well-saturated polarization-electric field (P-E) switching curves with the remanent polarization (Pr) of 51 μC/cm2 and the coercive field (Ec) of 99 kV/cm at an applied voltage of 10 V. More importantly, the Pt/Bi3.15Nd0.85Ti3O12/Pt capacitor exhibited fatigue-free behavior up to 4.5×1010 read/write switching cycles at a frequency of 1 MHz. The capacitor also demonstrated an excellent charge-retaining ability and a strong resistance against the imprinting failure. 相似文献
17.
通过sol-gel法在Si (111) 基片上分别制备了LaNiO3(LNO)底电极和LaNiO3/La0.3Sr0.7TiO3 (LNO/LSTO)底电极.然后采用sol-gel 方法,在两种衬底上分别制备了Pb (Zr0.5Ti0.5)O3 (PZT)铁电薄膜.XRD分析表明,两种PZT薄膜均具有钙钛矿结构,且在LNO底电极上的PZT薄膜呈(100) 择优取向,而在LNO/LSTO底电极上的PZT薄膜呈随机取向.铁电性能测试表明,相对LNO衬底上制备的PZT薄膜,在LNO/LSTO底电极上制备的PZT薄膜的剩余极化强度得到了有效的增强,同时矫顽场也增大.介电常数和漏电流的测试表明,LNO/LSTO底电极上制备的PZT薄膜具有大的介电常数和漏电流.
关键词:
PZT薄膜
铁电性
漏电流
0.3Sr0.7TiO3')" href="#">La0.3Sr0.7TiO3 相似文献
18.
The generally accepted mechanism of electrochromic phenomena into WO3 thin films involves the simultaneous injection of cations and electrons to form a tungsten bronze MxWO3, e.g. HxWO3,LixWO3. Electrochromic cells of the type ITO MO3/LiClO4(M) in propylene carbonate/Pt, where M = W or MO and MO3 is an amorphous thin film have been used. Different amounts of charges have been injected through these cells by electrochemical means at room temperature. The variations of the MO3 electrode potential with the injected charge are in good agreement with the assumption of the formation of LixMO3 compounds. The free enthalpies of formation of these bronzes have been calculated. The behavior of thin film electrodes seems to be intermediate between amorphous and crystallized bulky materials. Some measurements of electrode potential have also been carried out with crystallized thin films of sputtered WO3. 相似文献
19.
Ba0.5Sr0.5TiO3 (BST) thin films were deposited on copper foils via sol-gel method with La2O3 as a buffer layer. The films were processed in almost inert atmosphere so that the substrate oxidation was avoided while allowing the perovskite film phase to crystallize. The existence of a La2O3 buffer layer between the BST thin film and Cu foil improved the dielectric constant and reduced the leakage current density of the BST thin film. Meanwhile, the BST thin film exhibited ferroelectric character at room temperature, which was contrast to the para-electric behavior of the film without the buffer layer. Effects of La2O3 buffer layer on the crystallizability and microstructure of BST thin films were also investigated. 相似文献
20.
Cheng-Liang HuangSih-Yin Wang Yuan-Bin Chen Bing-Jing LiYing-Hong Lin 《Current Applied Physics》2012,12(3):935-939
Thin films of MgTiO3 high-k dielectric have been prepared by RF magnetron sputtering deposition at various substrate temperatures. X-ray diffraction, atomic force microscopy were used to characterize the deposited films. Experimental results show that substrate temperature has little effect on the stoichinometry. The electrical properties of MgTiO3 metal-insulator-metal (MIM) capacitors were investigated at various deposition temperatures, Pt/MgTiO3/Pt/SiO2/n-Si, were studied. It is shown that the MgTiO3 (210 nm) MIM capacitor fabricated at 200 °C shows an overall high performance, such as a high capacitance density of ∼1.2 nF/um2, a low leakage current of 1.51 × 10−9 A/cm2 at 5 V, low-voltage coefficients of capacitance, and good frequency dispersion properties. All of these indicate that the MgTiO3 MIM capacitors are very suitable for use in Si analog circuit application or dynamic random access memory (DRAM) cell. 相似文献