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1.
Investigation on the electrical characteristics of sol-gel derived Pb1.05(Zr0.53Ti0.47)O3 thin films
Abstract Lead zirconate titanate (PZT) thin films with composition Zr/Ti ~ 0.53/0.47 were deposited by the sol-gel technique. The films were characterized in terms of its polarization relaxation, fatigue and imprint characteristics. We have found that the polarization relaxation is due to the presence of a depolarization field which increases dramatically with the rise in temperature. Improved fatigue performance was observed when the film was fatigued with higher frequency. The direction of imprint depends on the state of polarization. With the increase in net polarization, the trapped charge density at the film-electrode interface increases which leads to imprint characteristics. Also the imprint increases considerably with the rise in temperature. Finally, we have made an attempt to correlate simultaneously fatigue, polarization relaxation, and imprint characteristics with the presence of mobile charge defects (viz. Vo) and defect dipoles (viz. VPb – Vo) in the film. 相似文献
2.
M. Tsukada H. Yamawaki M. Kondo J. S. Cross K. Kurihara 《Journal of Electroceramics》2004,13(1-3):29-33
Thin films made of (100)/(001)-oriented Pb(Zr, Ti)O3 (PZT) were deposited by liquid-delivery metal-organic chemical vapor deposition on Ir/MgAl2O4/SiO2/Si(100) substrates. For comparison, PZT thin films were also deposited on Ir/MgO(100) substrates. The X-ray scan spectra for the (202) reflections revealed that the PZT films have four-fold symmetry. It indicates that the PZT films were epitaxially grown as a cube-on-cube structure on both substrates. The switchable polarization (Qsw) of the PZT capacitors on the silicon substrate was only 23 C/cm2 at 1.8 V; however, Qsw of PZT capacitors on MgO was 99 C/cm2. In the case of PZT films deposited on silicon, the volume fraction of (001)-oriented domains (which contribute to polarization switching) was 15.1% (calculated from an XRD pattern). This result is due to the lower Qsw of PZT capacitors on silicon. By piezoresponse-force microscopy, switchable and unswitchable domains could be identified by imaging color contrast, namely, (001) and (100) domains, respectively. Consequently, domain distribution of the PZT film on a silicon substrate indicates that the (001) domain exists in the (100) domain matrix. 相似文献
3.
V. K. YARMARKIN 《Integrated ferroelectrics》2013,141(1):29-34
An impedance analysis of Ni/Pb(Zr,Ti)O3/Pt thin-film structures based on measurements at the frequencies from 100 Hz to 100 MHz, along with the data of Grazing Angles XRD, TEM and photo-electric study, is used to obtain electronic structure of the PZT thin films deposited by sol-gel method on silicone substrates. Both slow capacitance relaxation and charging/discharging currents versus time under step-voltage excitation have been studied in (Ba,Sr)TiO3 thin films between SrRuO3 electrodes. 相似文献
4.
《Integrated ferroelectrics》2013,141(1):707-712
In this study, we report the deposition of crack-free transparent PZT films (up to ~859 nm) by metallo-organic decomposition (MOD) process on amorphous silica substrate. Effect of SrTiO3 (STO) buffer layer on the growth behavior of PZT thin films deposited on SiO2-coated silicon substrates was systematically studied. Perovskite phase, which cannot be formed directly on SiO2/Si substrates, has been obtained when a thin STO film (~150 nm) was used as buffer layer. A SIMS examination indicates that the upward diffusion of Si-species into PZT layer is minimal, although downward diffusion of Pb-species into the SiO2 layer is still observable. 相似文献
5.
Abstract Ferroelectric capacitive devices for memory and MEMS applications require patterned ferroelectric thin films with high anisotropic etched features. In this paper, physical and chemical parameters during etching of Pb(Zr0.53Ti0.47)O3 (PZT) by a dual frequency ECR/RF reactor have been investigated. The removal characteristics of blanket films and films with a patterned mask were investigated as a function of gas chemistry (Ar, halogen gases), substrate bias RF power and working pressure (from 5 × 10?4 Pa to 1Pa). The etch processes were characterized in terms of etch rate, selectivity and mask stability. High etching rate processes (up to 70 nm/min with removable photoresist mask) were obtained and micron scale patterns were demonstrated. The impact of the etch process on the PZT surface layer modification was characterized by AFM, SEM, TEM and XPS. A strong influence of process chemistry and RF bias power on etching selectivity and surface topography (roughness, involatile residues) was observed. No surface damage layer was detected by Transmission Electron Microscopy. However, XPS revealed fluorine (up to 34%) and chlorine radicals (below 10%) in a 10nm thick surface layer. 相似文献
6.
Jun-Kyu Paik Sanghun Shin Sun-Woong Na Nae-Eung Lee Jaichan Lee 《Integrated ferroelectrics》2013,141(1):383-390
ABSTRACTMultilayered piezoelectric micro-diaphragms have been successfully fabricated by micro-electro-mechanical-system (MEMS) processing. The micro-diaphragms consisted of diol based sol-gel derived Pb(Zr0.52Ti0.48)O3 (PZT) capacitor, sputtered Pt electrode, and low temperature oxide(LTO)/SiNx/Si substrate. The PZT film exhibited (111) oriented structure. The dielectric constant and loss of the PZT thin films were 800 and 3% at 100~ 100 kHz, respectively. The remanent polarization was 20 μ C/cm2. The lateral dimension of the PZT film was varied relative to the square-shaped supporting membrane with 300 or 400 μ m length. The relative size (ratio of lateral dimensions) of the PZT film to the supporting membrane was varied from 0.7 to 1.1 to investigate its influence on the system performance. The micro-diaphragm exhibited mechanical displacement from 0.067 to 0.135 μ m at 15 V and had a maximum displacement at a ratio of relative size of 0.8, regardless of the lateral size of the supporting membrane. The fundamental resonant frequency of the micro-diaphragm which has 300 μ m length supporting membrane was in the range of 348 kHz to 365 kHz, depending on the relative size. As the PZT size increased relative to the supporting membrane, the resonant frequency decreased and reached a minimum at the relative size of 0.8. The micro-diaphragm with the supporting membrane (400 μ m length) had a lower resonant frequency, i.e., 251~270 kHz, but showed a similar behavior to the micro-diaphragm with the supporting membrane (300 μ m length) in relation to the resonant frequencies with the relative size. 相似文献
7.
MASAFUMI KOBUNE YUSUKE NISHIOKA TETSUO YAZAWA HIRONORI FUJISAWA MASARU SHIMIZU 《组合铁电体》2013,141(1):145-155
Pb(Zr0.52Ti0.48)O3 films with highly uniform c-axis orientation were fabricated on PbTiO3 (PT)/ Pt(111)/SiO2/Si(100) substrates by hot isostatic pressing (HIP) from the amorphous state. All the PZT samples HIP-treated 500°C for 1 h under gas pressures of 1.0–2.0 MPa showed the preferred (001) orientation with c-axis orientation, α > 0.80. The relative permittivity tended to decrease gently with increasing HIP pressure, whereas the dielectric loss increased almost linearly in the 1.5–100 MPa. The PZT sample treated at 1.5 MPa had a symmetric and slim hysteresis loop shape with a remanent polarization, P r = 15 μ C/cm2 and coercive field, E c = 60 kV/cm. Both samples treated at 10 and 100 MPa exhibited almost the fatigue-free behavior that resisted degradation even after 3 × 1010 cycles. 相似文献
8.
The Ba(Zr0.35Ti0.65)O3 (BZT) thin films were deposited via sol-gel process on LaNiO3-coated silicon substrates. XRD showed that the crystallinity of BZT film grown on LaNiO3 coated silicon substrates is better than that of BZT film grown on Pt. Both films showed perovskite phase and polycrystalline structure. The temperature dependent dielectric measurements revealed that the thin films had the relaxor behavior and diffuse phase transition characteristics. The capacitor tuning was about 44% for each BZT film grown on LaNiO3/Pt and Pt electrodes at 1 MHz. Especially, the values of dielectric loss at 1 MHz ranged from 0.02 to 0.009 in the bias range of 0 to 514 kV/cm, respectively. The leakage currents density of thin films grown on LaNiO3/Pt and Pt electrodes at 300 kV/cm was about 8.5 × 10–7 and 1.1 × 10–5 A/cm2, respectively. This work demonstrates a potential use of BZT films for application in tunable microwave devices. 相似文献
9.
《Integrated ferroelectrics》2013,141(1):515-525
The piezoelectric and the pyroelectric properties of PZT films are systematically investigated for tetragonal (Zr/Ti = 30/70), morphotropic (52/48), and rhombohedral (70/30) compositions. The magnitude of the effective longitudinal piezoelectric coefficient (d33) and pyroelectric coefficient (p) of these films is measured by atomic force microscopy and Byer-Roundy method, respectively. All films are consistently highly textured (111) orientation and have dense microstructures. Slightly less degree of texture in higher Zr-rich composition is observed due to the lattice mismatch between PZT and Pt bottom electrode and higher activation energy for nucleation. Squareness of polarization hysteresis loops is optimized in tetragonal composition, which indicates the tetragonal PZT is closer to the ideal hysteresis behavior than other compositions. It is shown that the piezoelectric coefficient and the pyroelectric figure of merit are dependent on the dielectric properties of the films. The morphotropic PZT films with high dielectric constant and low pyroelectric figure of merit show the largest piezoelectric coefficient values, while the tetragonal PZT films with low dielectric constant and high remanent polarization values show the largest pyroelectric figure of merit compared to other compositions, which indicate the suitability for PIR sensor devices. 相似文献
10.
《组合铁电体》2013,141(1):659-664
Ferroelectric Pb(Zr1 ? x Ti x )O3 (PZT) films were deposited on (001) MgO single crystals using sol-gel method. Structural properties and surface morphologies of PZT films were investigated using an X-ray diffractometer and a scanning electron microscopy, respectively. The dielectric properties of PZT films were investigated with the dc bias field of 0–135 kV/cm using interdigitated capacitors (IDC) which were fabricated on PZT films using a thick metal layer by photolithography and etching process. The small signal dielectric properties of PZT films were calculated by a modified conformal mapping method with low and high frequency data, such as capacitance measured by an impedance gain/phase analyzer at 100 kHz and reflection coefficient (S-parameter) measured by a HP 8510C vector network analyzer at 1–20 GHz. The IDC on PZT films exhibited about 67% of capacitance change with an electric field of 135 kV/cm at 10 GHz. These PZT thin films can be applied to tunable microwave devices such as phase shifters, tunable resonators and tunable filters. 相似文献
11.
Abstract Pulsed laser ablation has been used to deposit ferroelectric Pb(Zr, Ti)O3 (PZT) thin films on Si(100) and on yttrium-treated Si(100) substrates. The yttrium (Y) treatment of a Si surface followed by oxidation resulted in formation of a very thin, Y-enhanced SiO2 antidiffusion barrier layer, thereby suppressing the undesirable PZT/Si interdiffusion. The best PZT film grown on Y-treated Si(100) had a breakdown voltage of 0.6 MV/cm, a coercive field of 71 KV/cm, and a remanent polarization of 18 μC/cm2. 相似文献
12.
H. N. Al-Shareef K. R. Bellur O. Auciello A. I. Kingon 《Integrated ferroelectrics》2013,141(3):185-196
Abstract Pb(Zr0.53Ti0.47)O3 (PZT) thin films were deposited on Pt and RuO2 coated Si and MgO substrates using the sol-gel process. Fatigue and retention tests were performed on these samples. The films grown on RuO2 electrodes are fatigue-free up to nearly 1011 cycles. Their retention life-time extrapolates to more than 1010 seconds. The fatigue behavior of films grown on Pt electrodes depends on the PZT film orientation. Highly oriented (001) PZT films maintain 50% of their initial P?r-P?r value after 1011 cycles. The randomly oriented films maintain less than 3% of the initial P?r-P?r value after 1011 cycles. However, the retention life-time of both highly oriented and randomly oriented PZT films grown on Pt electrodes extrapolates to higher than 1011 seconds. It appears that fatigue of films grown on RuO2 is mainly controlled by the film/electrode interface. On the other hand, fatigue of films grown on Pt appears to depend on both the film/electrode interface as well as on bulk effects. 相似文献
13.
H. N. Al-Shareef K. R. Bellur O. Auciello A. I. Kingon 《Integrated ferroelectrics》2013,141(1-2):151-163
Abstract Growth of Pb(Zr0.53Ti0.47)O3 (PZT) thin films on RuO2 electrodes by the sol-gel process is usually accompanied by the formation of second phases. The resulting RuO2/PZT/RuO2 capacitors are fatigue-free up to nearly 1011 switching cycles, but they have high leakage currents (J~10?3 A/cm2 at 1 volt) and large property variation. We have developed several modifications of the RuO2 bottom electrode which enhance nucleation of the perovskite phase, eliminate or reduce the second phases, and control film orientation and properties. The PZT films deposited on the modified RuO2 electrodes have leakage current densities which are two to four orders of magnitude lower than those of PZT films deposited on the unmodified RuO2 electrodes. In most cases, the excellent resistance to polarization fatigue which is characteristic of the RuO2/PZT/RuO2 capacitors, is maintained. 相似文献
14.
《Integrated ferroelectrics》2013,141(1):1475-1482
Ferroelectric PZT thin films were deposited by liquid delivery MOCVD using a cocktail solution. The cocktail solution consisted of Pb(METHD)2, Zr(METHD)4 and Ti(MPD)(METHD)2 diluted with ethylcyclohexane. The films deposited on Pt/Ti/SiO2/Si at a substrate temperature of 500°C consisted of PZT, PbO and PbPtx, and showed poor properties. However, after annealing at 450°C in air for thirty minutes, the PbPtx phase disappeared while the volume of the PbO phase increased. The hysteresis properties were also improved by annealing at 450°C. After annealing at 600°C in air for thirty minutes, the PbPtx and the PbO phases disappeared perfectly and the PZT thin films showed good hysteresis properties with the remanent polarization of 30 μC/cm2 and the coercive field of 88 kV/cm. 相似文献
15.
Myong-Ho Kim A. Golovchanski Soon Il Lee Tae-Gone Park Tae Kwon Song 《Journal of Electroceramics》2004,13(1-3):367-371
Nano-size powders of lead zirconate titanate (PZT) were fabricated by a new milling coprecipitation method (MCP) improved from the conventional wet ball milling and precipitation. This method consists of slurry preparation from nanoparticles of TiO2 with aqueous solution of ZrO(NO3)2 and Pb(NO3)2 with zirconia ball mill media, followed by precipitation with NH4OH as precipitant. Milling media (1mm and 3mm balls) improves the precipitation homogeneity during processing. Single-phase perovskite structure of PZT was formed at a calcination temperature of 500C and powders of 50 nm particle size were obtained. Powders were characterized using TG-DTA, SEM and XRD methods. Sintering ability of powders and piezoelectric properties of the ceramics were also investigated. 相似文献
16.
Bilayered thin films consisting of Pb(Zr0.52Ti0.48) O3 (PZT) and (Bi3.15Nd0.85)Ti3O12 (BNT) layers are successfully deposited on Si(100)/SiO2/Ti/Pt substrate by a combined process involving sol-gel and RF-sputtering. Their dielectric properties cannot be described
by the simple rule of mixture on the basis of the series connection model. There occurs a dielectric layer of lower dielectric
permittivity in the bilayered thin film, which degrades the polarization behaviors. The bilayered film gives rise to an improvement
in fatigue resistance up to 1010 switching cycles. Moreover, the domain pinning effect after polarization switching is reduced greatly as compared to that
of single layered PZT and BNT thin films. 相似文献
17.
We demonstrate a water-immersible thin film lead zirconate titanate, Pb(Zr, Ti)O3, [PZT] actuator, without special passivation layer, towards in-vivo or in-vitro scanning probe microscope (SPM) measurements of living cells in water or biological fluids. In order to be water-immersible, the electrodes need to be electrically insulated and the piezoelectric layer needs to be protected against direct water contact. This paper describes our design solution with a simple fabrication process for a water-immersible piezoelectric device, which separates the bottom electrode from the top electrode by having a narrow ditch covered with PZT film. The PZT film is then encapsulated with the top metal electrode without insulation layer. In this structure, the PZT is sandwiched between the top and bottom metal electrodes to prevent water permeation. The device is fabricated using lift-off processing for the bottom and top electrodes, sol-gel spinning for the PZT thin film and wet etching for the PZT patterning. The piezoelectric constant, d31, is about –100 pC/N. The dielectric polarization and fatigue properties of the devices were measured in air and water. The spontaneous polarization, remnant polarization, coercive field and dielectric constant are 54 C/cm2, 15 C/cm2, 60 kV/cm and 1200, respectively. The polarization property of the device was unchanged in either air or water up to 1 × 109 continuous cycles. 相似文献
18.
Shintaro Yokoyama YOSHIHISA HONDA HITOSHI MORIOKA SHOJI OKAMOTO TAKASHI IIJIMA HIROFUMI MATSUDA 《Integrated ferroelectrics》2013,141(1):217-225
(001)-/(100)-oriented epitaxial PZT films and fiber-textured PZT films with a thickness of 2 μ m were deposited on (100) c SrRuO3//(100)SrTiO3 and (111)Pt/TiO2/SiO2/(100)Si substrates, respectively, by metalorganic chemical vapor deposition (MOCVD). Crystal structure and the electrical properties were compared for epitaxial PZT films with those of fiber-textured ones, which had the same out-of-plane orientation but different in-plane orientation. The constituent phase change from the single phase of tetragonal PZT, mixture phases of tetragonal and rhombohedral ones and the single phase of rhombohedral one for both films when the Zr/(Zr + Ti) ratio increased. The out-of-plane lattice parameter of (001)- and (100)-axes of PZT films were almost the same value for both films. This indicates the residual strain in the PZT films was almost the same. Dielectric constant (? r) took the maximum value around the MPB composition for (001)-/(100)-oriented fiber-textured films but was almost independent of the Zr/(Zr + Ti) ratio for epitaxial ones. Moreover, there was no significantly dependence of remanent polarization (P r) value on the Zr/(Zr + Ti) ratio for (001)-/(100)-oriented fiber-textured films, while it took minimum value near the morphotropic phase boundary (MPB) for epitaxial ones. 相似文献
19.
Seung Eon Moon Eun-Kyoung Kim Su-Jae Lee Min-Hwan Kwak Young-Tae Kim Han-Cheol Ryu Won-Jeong Kim Tae-Kwun Song 《Journal of Electroceramics》2004,13(1-3):257-260
Ferroelectric Pb(Zr1–xTix)O3 (PZT) thin films were prepared by sol-gel deposition method. The structural and surface morphologies were investigated using X-ray diffractometer and atomic force microscope. Microwave dielectric properties were obtained using co-circle electrode patterns, which were made by photolithography and etching process. The dielectric constant of PZT films was about 450 from 0.05–1 GHz range. 相似文献
20.
《Integrated ferroelectrics》2013,141(1):1221-1231
Metal-ferroelectric-(insulator)-semiconductor MF(I)S structures have been fabricated and the properties of pulsed laser-deposited PZT/Al2O3 gate stacks have been studied on n- and p-type 4H-SiC. Among several polytypes of SiC, 4H-SiC is considered as the most attractive one because of its wider bandgap (E g ? 3.2 eV) as well as higher and more isotropic bulk mobility than other polytypes. Single PZT phase without a preferred orientation was confirmed by x-ray diffraction. The interface trap densities N IT, fixed oxide charges Q F, and trapped oxide charges Q HY have been estimated by C-V curves with and without photo-illuminated measurements at room temperature. It is found that the charge injection from SiC is the dominant mechanism for C-V hysteresis. Importantly, with PZT/Al2O3 gate stacks, superior C-V characteristics with negligible sweep rate dependence and negligible time dependence under the applied bias were obtained compared to PZT directly deposited on SiC. The MFIS structures exhibited very stable capacitance-voltage C-V loops with low conductance (<0.1 mS/cm2, tan δ ~ 0.0007 at 400 kHz) and memory window as wide as 10 V, when 5 nm-thick Al2O3 was used as a high bandgap (E g ~ 9 eV) barrier buffer layer between PZT (E g ~ 3.5 eV) and SiC (E g ~ 3.2 eV). The structures have shown excellent electrical properties promising for the gate stacks as the SiC field-effect transistors (FETs). Depletion mode transistors were prepared by forming a Pb(Zr0.52Ti0.48)O3/Al2O3 gate stack on 4H-SiC. Based on this structure, ferroelectric Pb(Zr,Ti)O3 (PZT) thin films have been integrated on 4H-silicon carbide (SiC) in a SiC field-effect transistor process. Nonvolatile operation of ferroelectric-gate field-effect transistors in silicon carbide (SiC) is demonstrated. 相似文献