共查询到20条相似文献,搜索用时 46 毫秒
1.
《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
2.
Hassan Aldeeb 《组合铁电体》2014,157(1):95-100
A tunable double band band-stop filter based on BST is presented. This configuration has a coplanar microstrip loaded with stepped impedance resonators. Ferroelectric BST parallel plate capacitors were loaded at the end of the stepped impedance resonators. When a DC voltage is applied to the BST capacitors, the change in capacitance shifts the resonance frequency of the stepped impedance transformers. The filters were designed with notch frequencies at 1.5 GHz and 3.5 GHz without loading them with BST capacitors. The filter circuits were simulated with Agilent ADS and were fabricated on FR-4 substrates. By loading the resonators with BST capacitors with no DC applied voltage, the first and second notch frequency shifts significantly. The first notch frequency can be tuned from 570 MHz to 781 MHz and the second notch frequency from 2.16 GHz to 2.55 GHz by applying the bias voltage of 5volts. The performance of the BST tuned filters were compared with filters tuned with p-n junction varactors. 相似文献
3.
In this study, the microwave dielectric and the acoustic properties of Pb(Zr
x
,Ti1-x
)O3 (PZT) thin films deposited using chemical solution deposition (CSD) were investigated using the same measurement setup. High
dielectric constants in the range of ~280–540 and loss tangents less than 0.1 at 4 GHz were measured, where the value depends
on the thickness of the PZT film. The voltage tunability of the 340 nm and 440 nm thick PZT thin films was ~34% and 5% for
the 140 nm thick PZT film at 120 kV/cm and 4 GHz. The acoustic parameters of the PZT thin films under DC bias voltages were
determined using a one-dimensional acoustic wave resonator model. For the PZT films of thicknesses 340 nm and 440 nm, the
acoustic resonance frequency shift was about 15 MHz and the electromechanical coupling coefficient was ~10% at an electric
field of 160 kV/cm. The large dielectric constant and high tunability suggest that the characterized PZT thin films may be
suitable for radio frequency (RF) applications such as high-density RF MIM capacitors and other tunable devices. 相似文献
4.
Mi-Hwa Lim Hyun-Suk Kim Nan-Young Kim Ho-Gi Kim Il-Doo Kim Seung Eon Moon Min-Hwan Kwak Han-Cheol Ryu Su-Jae Lee 《Journal of Electroceramics》2004,13(1-3):239-243
Highly (100) preferred undoped and 1–5% Ni-doped Ba1–xSrxTiO3 (BST) thin films were deposited onto MgO (100) single crystal substrate at 750°C using pulsed laser deposition. BST thin film-based interdigital capacitors (IDC) were prepared by standard photolithography process. The microwave properties of BST films were measured at 10 GHz. Ni-doped BST films showed better dielectric properties by exhibiting improved dielectric Q while retaining an appropriate capacitance tuning compared to undoped BST films. 1% Ni-doped BST film showed the maximum figure of merit of 2896.1. It is suggested that 1 mol% Ni doped BST film is an effective candidate for high performance tunable device applications. 相似文献
5.
Hai-Joon Lee Chang Won Ahn Sun Hee Kang Chang Do Kim Ill-Won Kim Jin Soo Kim Jeong Sik Lee 《Journal of Electroceramics》2008,21(1-4):851-854
The Bi3.15Nd0.85Ti3O12 (BNT) thin films were deposited on Pt(111)/Ti/SiO2/Si substrates by using RF-magnetron sputtering method and studied the ferroelectric and leakage current charateristics. The polarization – electric field (P-E) hysteresis loops of BNT film was well saturated with the remnant polarization (2P r ) of 29.8 μC/cm2 and a coercive field (2E c ) of 121 kV/cm. The leakage current density – electric field (J-E) characteristics of the Pt/BNT/Pt capacitor reveals the presence of two conduction region, having Ohmic behavior at low electric field (below 50 kV/cm) and Schottky-emission or Poole-Frenkel emission at high electric field (above 60 kV/cm). The barrier height and trapped level of BNT films are estimated to be 1.11 eV and 0.90 eV, respectively. 相似文献
6.
《Integrated ferroelectrics》2013,141(1):877-885
(Ba0.5Sr0.5)TiO3 (BST) thin films were deposited by pulsed laser deposition (PLD) and investigated as a function of Ni dopant concentration in low and high frequency regions. In low frequency region (<10 MHz), the Ni-dopant concentration in BST films has a strong influence on the material properties including dielectric and tunable properties. Ni-doped (≤3 mol%) BST films showed denser, smoother morphologies and smaller grain sizes than those with 6 and 12 mol% Ni. Dielectric constant and loss of 3 mol% Ni-doped BST films were about 980 and 0.3%, respectively. In addition, tunability and figure of merit of 3 mol% doped BST films showed maximum values of approximately 39% and 108, respectively. In high frequency region (>1 GHz), the frequency tunability range at center frequency of undoped BST and 3 mol% Ni-doped BST coplanar waveguide (CPW) resonators showed 102 and 152 MHz, respectively at 30 V dc bias. The Ni-doped BST thin films are possible in applications of microwave tunable capacitors. 相似文献
7.
Robert A. York Amit S. Nagra Padmini Periaswamy Orlando Auciello Stephen K. Streiffer Jaemo Im 《Integrated ferroelectrics》2013,141(1-4):177-188
Abstract Precise control of composition and microstructure is critical for the production of (BaxSr1?x)Ti1+yO3+z (BST) dielectric thin films with the large dependence of permittivity on electric field, low losses, and high electrical breakdown fields that are required for successful integration of BST into tunable high frequency devices. Here we review recent results on composition-microstructure-electrical property relationships of polycrystalline BST films produced by magnetron sputter deposition, that are appropriate for microwave devices such as phase shifters. Films with controlled compositions were grown from a stoichiometric Ba0.5Sr0.5TiO3 target by control of the background processing gas pressure. It was determined that the (Ba+Sr)/Ti ratios of these BST films could be adjusted from 0.73 to 0.98 by changing the total (Ar+O2) process pressure, while the O2/Ar ratio did not strongly affect the metal ion composition. Film crystalline structure and dielectric properties as a function of the (Ba+Sr)/Ti ratio are discussed. Optimized BST layers yielded capacitors with low dielectric losses (0.0047), among the best reported for sputtered BST, while still maintaining tunabili-ties suitable for device applications. These BST films were used to produce distributed-cir-cuit phase-shifters, using a discrete periodic loading of a coplanar waveguide with integrated BST varactors on high-resistivity silicon. Phase shifters yielding 30 degrees of phase shift per dB of insertion loss were demonstrated at 20GHz. 相似文献
8.
Hyun-Suk Kim Il-Doo Kim Ki-Byoung Kim Tae-Soon Yun Jong-Chul Lee Harry L. Tuller Won-Youl Choi Ho-Gi Kim 《Journal of Electroceramics》2006,17(2-4):421-425
We report on high tunablity of Ba0.6Sr0.4TiO3 (BST) thin films realized through the use of atomic layer deposited TiO2 films as a microwave buffer layer between BST and a high resistivity (HR) Si substrate. Coplanar waveguide (CPW) meander-line
phase shifters using BST/TiO2/HR-Si and BST/MgO structures exhibited a differential phase shift of 95∘ and 24.4∘, respectively, at 15 GHz under an electric field of 10 kV/cm. The figure of merit of the phase shifters at 15 GHz was 30.6∘/dB for BST film grown on a TiO2/HR-Si substrate and 12.2∘/dB for BST film grown on a MgO single crystal substrate. These results constitute significant progress in integrating BST
films with conventional silicon technology. 相似文献
9.
Minghui Zhang Hong Wang Haibo Yang Weihong Liu Huanfu Zhou Xi Yao 《Journal of Electroceramics》2011,26(1-4):99-104
Ba0.6Sr0.4TiO3 thick films were fabricated at a lower temperature of 880°C by adding Li2O as sintering aid. A novel pretreatment of cold isostatic pressing was introduced to enhance the quality of films. After cold isostatic pressing prior to annealing, the thick film had a more compact morphology and better dielectric properties. The permittivity and tunability were increased to 1,318 and 19.04% from 925 and 14.81% while the dielectric loss was still kept low (1 MHz, 16 kV/cm). The enhanced properties and low-temperature sintering made BST thick films a potential candidate for Low Temperature Co-fired Ceramic (LTCC) and microwave tunable devices. 相似文献
10.
SEUNG EON MOON MIN HWAN KWAK YOUNG-TAE KIM HAN-CHEOL RYU SU-JAE LEE KWANG-YONG KANG 《组合铁电体》2013,141(1):275-281
(001) oriented (Sr,Ba)Nb2O6 (SBN) thin films were deposited on MgO (001) single crystal substrates by the pulsed laser deposition method. Structural properties of SBN films were investigated using X-ray diffractometer. The microwave dielectric properties of SBN films were examined by calculating the scattering parameter obtained using a HP 8510C vector network analyzer with the frequency range 0.5–20 GHz at room temperature under the dc bias field of 0–80 kV/cm for interdigital capacitors (IDT) and coplanar waveguide (CPW) device based on SBN/MgO layer structure. Thick metal electrode patterns were fabricated by dc sputtering deposition, photolithography and etching process. The IDT device based on (001) oriented SBN films exhibited about 40% capacitance tunability with an electric field change of 80 kV/cm at room temperature, and the dielectric quality factor was about 20 at 12 GHz with no dc bias. 相似文献
11.
Jaemo Im O. Auciello P. K. Baumann S. K. Streiffer D. Y. Kaufman A. R. Krauss 《Integrated ferroelectrics》2013,141(1-4):263-270
Abstract High permittivity (BaxSr1?x)Ti1+yO3+z(BST) thin films are being investigated for integration into charge storage dielectrics and electric-field tunable elements for high frequency devices. For the latter application, it is desirable to have BST capacitors with high tunability and low losses. Therefore, we investigated the use of multilayer BST thin films consisting of very low dielectric loss BST/electrode interfacial layers ((Ba+Sr)/Ti = 0.73) sandwiching a high tunability, high permittivity primary BST layer ((Ba+Sr)/Ti = 0.9). BST capacitors with multiple layers of controlled composition can be effectively produced insitu by magnetron sputter deposition, using a single stoichiometric target and controlling the layer composition by changing the total process gas (Ar+O<2) pressure. The layered BST film capacitors exhibit simultaneous low loss (tan Δ = 0.005), high tunability (76%), high charge storage energy density (34 J/cm3), low leakage, and high dielectric breakdown (>2.8 MV/cm). 相似文献
12.
Transition metal (Ni, Mn, Cu) doped Bi0.9Nd0.1FeO3 thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method. Compared to pure BiFeO3 (BFO) thin film, improved ferroelectric and leakage current properties were observed in the transition metal doped thin films. The values of remnant polarization (2P r ) and coercive electric field (2E c ) of the transition metal doped thin films were 59 μC/cm2 and 690 kV/cm at 700 kV/cm for the Ni-doped Bi0.9Nd0.1FeO3 thin film, 57 μC/cm2 and 523 kV/cm at 670 kV/cm for the Mn-doped thin film, and 85 μC/cm2 and 729 kV/cm at 700 kV/cm for the Cu-doped thin film, respectively. The 2P r values observed in the transition metal doped thin films were much larger than that of the BFO thin film, 21 μC/cm2 at 660 kV/cm. Also the 2E c values of in the transition metal doped thin films were lower than that of the BFO thin film, 749 kV/cm at 660 kV/cm. The reduced leakage current density was observed in the transition metal doped thin films, which is approximately two orders of magnitude lower than the BFO thin film, 2.6?×?10?3 A/cm2 at 100 kV/cm. 相似文献
13.
Francisco Ayguavives Zhang Jin Ali Tombak Jon Paul Maria Amir Mortazawi Angus I. Kingon 《Integrated ferroelectrics》2013,141(1-4):393-402
Abstract Recently, there has been significant interest in use of (Ba,Sr)TiO3 (BST) thin films for tunable high frequency (RF and microwave) components. In a previous work we have shown that BST thin films grown by metalorganic chemical vapor deposition (MOCVD) exhibit films very low losses (as low as 0.003–0.004) and tunabilities over 50% at low operation voltages. In order to integrate BST thin films in tunable devices, the objectives of this work are : (i) study the effect of bottom and top electrode on the performance of thin film based capacitors, (ii) correlate low frequency (10 kHz) and high frequency (45 MHz - 1 GHz) measurements, (iii) separate the contribution of dielectric losses and metallic losses at both low and high frequency and finally (iv) show the potential usefulness of series capacitors structures. 相似文献
14.
S. S. Kim E. K. Choi H. J. Kim M. H. Park H. S. Lee W. J. Kim J. C. Bae T. K. Song H. S. Lee J. Y. Lee 《Journal of Electroceramics》2004,13(1-3):83-88
Ferroelectric properties of samarium substituted Bi4Ti3O12 films, Bi3.15Sm0.85Ti3O12 (BST), were evaluated for use as lead-free thin film ferroelectrics for FeRAM applications. The BST films were fabricated on the Pt/Ti/SiO2/Si(100) substrates by a metalorganic solution deposition method. The measured XRD patterns revealed that the BST films showed only a Bi4Ti3O12-type phase with a random orientation. The BST film capacitors showed excellent ferroelectric properties. For the film capacitor annealed at 700C, 2Pr of 64.2 C/cm2 and 2Ec of 101.7 kV/cm at applied electric field of 150 kV/cm were observed. The capacitor did not show any significant fatigue up to 1.5 × 108 read/write switching cycles at a frequency of 1 MHz, which suggests that the samarium should be considered for a promising lanthanide elements to make a good thin ferroelectric film for memory applications. 相似文献
15.
Na0.5K0.5NbO3 (NKN) and Pb(Zr0.53Ti0.47)O3 (PZT) films have been grown by rf-magnetron sputtering and pulsed laser deposition techniques, correspondingly, on sapphire (Al2O3-0112, r-cut), quartz (Y+36°-cut) and YAlO3 + 1% Nd (Nd:YAlO3-001) single crystal substrates with Interdigital Capacitor (IDC) of Coplanar Waveguide (CPW) structure. Photolithography and metal lift-off technique was used for processing of the tunable microwave capacitor. Microwave network analyzer with G-S-G Picoprobe and probe station performed microwave measurement with external DC bias. NKN film interdigital capacitors on Nd:YAlO3 show superior performance in the microwave range from 1 to 40 GHz. Within this range, the voltage tunability (40 V, 200 kV/cm) was about 29%, loss tangent ~ 0.13, K-factor from 152% @10 GHz to 46% @40 GHz, voltage independent C p was about 230 fF, tan δ p changes from 0.14 @10 GHz to 0.36 @40 GHz, real and imaginary part of interconnect impedance increases with frequency from 0.13 Ω @10 GHz to 0.50 Ω @40 GHz and from 1.9 Ω @10 GHz to 5.9 Ω @40 GHz respectively. 相似文献
16.
The Effect of Stress on the Microwave Dielectric Properties of Ba0.5Sr0.5TiO3 Thin Films 总被引:1,自引:0,他引:1
James S. Horwitz Wontae Chang Wonjeong Kim Syed B. Qadri Jeffrey M. Pond Steven W. Kirchoefer Douglas B. Chrisey 《Journal of Electroceramics》2000,4(2-3):357-363
Single phase, (1 0 0) epitaxial Ba0.5Sr0.5TiO3 (BST) films have been deposited onto (1 0 0) LaAlO3 and MgO substrates by pulsed laser deposition (PLD). The capacitance and dielectric losses of as-deposited and annealed films have been measured from 1–20 GHz as a function of electric field (0–80 kV/cm) at room temperature. The dielectric properties are strongly affected by the substrate type, post-deposition annealing time (6 h) and temperature (1200°C). For epitaxial BST films deposited onto MgO, it is observed that, after a post-deposition anneal the dielectric constant and the dielectric loss decreases. For epitaxial BST films deposited onto LAO, a post-deposition anneal (1000°C) results in an increase in the dielectric constant and an increase in the dielectric loss. The dc electric field induced change in the dielectric constant tends to increase with the dielectric constant and is largest for as-deposited films on MgO and post-deposited annealed films on LAO. In general, for epitaxial BST films, a large electric field effect is observed in films that have a large dielectric loss and a small electric field effect in films that have a low dielectric loss. High resolution X-ray diffraction measurements indicate that deposited film exhibit a significant tetragonal distortion which is strongly affected by a by a post deposition anneal. The observed differences in dielectric properties of the epitaxial BST films on MgO and LAO are attributed to the differences in film stress which arise as a consequence of the lattice mismatch between the film and the substrate and the differences in the thermal coefficient of expansion between the film and the substrate. A thin amorphous buffer layer of BST has been used to relieve stress induced by the lattice mismatch between the film and the substrate. Unlike epitaxial films, stress relieved films do not show an inverse relationship between dielectric tuning and Q (1/tan) and may be superior materials for tunable microwave devices. 相似文献
17.
The Barium zirconium titanate Ba(Zr0.3Ti0.7)O3 thin films were prepared on Pt/Ti/SiO2/Si substrates with seed layers at the BZT/Pt interface by sol–gel process. Microstructure and structure of thin films were examined. Dielectric properties of thin films with various seed layers thicknesses were investigated as a function of frequency and direct current electric field. The tunability and dielectric constant of BZT thin films increased with increasing seed layer thickness from 0 to 20 nm, while it decreased with a further increase in thickness above 20 nm, meanwhile, the leakage current showed the similar tendency at applied electric field of 250 kV/cm. The optimized seed layer thickness for BZT thin films plays an important role in maintaining the high tunability and low leakage current, which are suitable for microwave device applications. 相似文献
18.
Abdelkader Outzourhit Ali Naziripour John U. Trefny Tomoko Kito Baki Yarar Robert Yandrofski 《组合铁电体》2013,141(4):227-241
Abstract Ba1?x Sr x TiO3 thin film capacitors have been successfully prepared using rf-sputtering and a metal organic deposition (MOD) method. The structure, microstructure and composition of the BSTO films are presented. Films grown on lanthanum aluminate LAO(100) showed c-axis preferred growth orientation. Broad paraelectric-to-ferroelectric transitions were observed in films prepared by both methods. The tunability of the capacitance by means of an appplied electric field is examined using various capacitor geometries. A decrease in the capacitance exceeding 75% at 77 K was obtained from the MOD deposited films under an electric field strength of 0.3 MV/cm. On the other hand, the tunability of the capacitance in the rf-sputtered films ranged from 5 to 10% at 77 K and at 20 kV/cm, while it exceeds 50% in some films. The results are compared with the predictions of Devonshire's phenomenological theory. 相似文献
19.
《Integrated ferroelectrics》2013,141(1):863-869
Epitaxial (111) oriented ferroelectric (Ba1 ? xSrx)TiO3 (BST) films were deposited on MgO (111) single crystals using pulsed laser deposition. Structural properties of BST films were investigated using X-ray diffractometer. The dielectric properties of BST films were investigated under the dc bias field of 0–40 V using interdigital capacitors (IDT) fabricated by photolithography and etching process. The small signal dielectric properties of BST films were calculated by modified conformal mapping both the measured data using an impedance gain/phase analyzer and the reflection coefficient data measured using a HP 8510C vector network analyzer in 0.05–10 GHz at room temperature. The IDT capacitor based on (111) oriented BST film exhibits about 40% of capacitance change with an dc bias of 40 V which value is somewhat smaller than that of the IDT device based on (001) oriented BST film. But the dielectric quality factor value is about twice that of the device based on (001) oriented BST film. 相似文献
20.
Microwave Performance of Distributed Analog Phase Shifter Using Ferroelectric (Ba,Sr)TiO3 Thin Films
《Integrated ferroelectrics》2013,141(1):689-696
This work presents the design, fabrication and microwave performance of distributed analog phase shifter (DAPS) fabricated on (Ba,Sr)TiO3 (BST) thin films for X-band applications. Ferroelectric BST thin films were deposited on MgO substrates by pulsed laser deposition. The DAPS consists of high impedance coplanar waveguide (CPW) and periodically loaded tunable BST interdigitated capacitors (IDC). In order to reduce the insertion loss of DAPS and to remove the alteration of unloaded CPW properties according to an applied dc bias voltage, BST layer under transmission lines were removed by photolithography and RF-ion milling. The measured results are in good agreement with the simulated results at the frequencies of interest. The measured differential phase shift based on BST thin films was 24° and the insertion loss decreased from ?1.1 dB to ?0.7 dB with increasing the bias voltage from 0 to 40 V at 10 GHz. 相似文献