W. B. Luo

University of Electronic Science and Technology of China, Hua-yang, Sichuan, China

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Publications (49)65.03 Total impact

  • W.B. Luo · P. Zhang · Y. Shuai · X.Q. Pan · Q.Q. Wu · C.G. Wu · C. Yang · W.L. Zhang
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    ABSTRACT: Forming free resistive switching property of TiO2 films deposited on Pt/Ti/SiO2/Si substrates was studied in this contribution. The surface morphology of TiO2 films were studied by atomic force microscopy (AFM). The chemic states of Ti and O elements were measured by X-ray photoelectron spectrum (XPS). The resistive switching property of the sample was measured using Au/TiO2/Pt capacitor structure fabricated by evaporating Au top electrode. Smooth surface and dense cross structure were observed by AFM and scanning electron microscopy. Oxygen vacancies in TiO2 film were confirmed by XPS. Forming free resistance switching was confirmed by the current–voltage measurement and the resistance ratio is larger than two orders of magnitude at 2.5 V. The XPS spectrum, asymmetric current loops and conduction mechanism fitting results indicated that the asymmetric electrode structure and oxygen vacancies are the origin of the resistive switching.
    No preview · Article · Jan 2016 · Thin Solid Films
  • W. B. Luo · Y. C. Yu · Y. Shuai · X. Q. Pan · Q. Q. Wu · C. G. Wu · W. L. Zhang
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    ABSTRACT: The effect of potassium-sodium niobate (KNN) powder sintering temperature on the structure and properties of the KNN/{poly(vinylidenefluoride-co-trifluoroethylene 70:30) [P(VDF-TrFE) 70:30]} composite thick films have been studied in this paper. KNN powders were sintered by solid-state reaction at different temperatures ranging from 750 to 900 °C. Then the KNN powders were used to fabricate composite thick films by casting the KNN/P(VDF-TrFE) suspension on to ITO substrates. The pyroelectric and dielectric properties of the composite thick films have been investigated systematically. It was found that sample made up of KNN ceramic powders sintered at 850 °C show optimal properties for pyroelectric appliance. The highest pyroelectric coefficient was 63 μCm−2/K and the highest detectivity figure-of-merit was 4.94 μPa1/2.
    No preview · Article · Nov 2015 · Journal of Materials Science Materials in Electronics
  • Source
    W.B. Luo · K. He · D. Xu · C. Li · X.Y. Bai · Y. Shuai · C.G. Wu · W.L. Zhang

    Full-text · Article · Oct 2015 · Journal of Alloys and Compounds
  • L. Jin · W. B. Luo · X. Qing · Y. Shuai · C. Yang · C. G. Wu · W. L. Zhang
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    ABSTRACT: Nd doping effects on the multifunction properties of BiFeO3 films, including ferroelectric, magnetic, and resistive switching properties, have been studied in this contribution. BiFeO3 (BFO) and Nd doped BiFeO3 (BNFO) films have been deposited on Pt/Ti/SiO2/Si substrates by pulsed laser deposition (PLD). The Nd doping not only changed the growth orientation and surface morphology but also impacted the ferroelectric, resistive switching and ferromagnetic properties of the BFO films. Saturated hysteresis loops were observed in BNFO films with remnant polarization of 86.4μCcm-2, while the pure BFO films show round hysteresis indicating obvious leaky characters. The magnetization of the BNFO films and that of the BFO films were demonstrated with remnant magnetization of 9.8 and 15.6emucm-3, respectively. Both BFO and BNFO films show resistive switching behaviours. Additionally, the current density of BNFO was reduced two orders of magnitude and this will be beneficial for the reduced power consumption of the future memory devices. X-ray photoelectron spectroscopy characterizations demonstrated that these results originated from the decrease of oxygen vacancies by Nd doping.
    No preview · Article · Jul 2015 · Material Research Innovations
  • X. Qing · Y. Shuai · L. Jin · P. Zhang · W. B. Luo · C. G. Wu · H. Z. Zeng · W. L. Zhang
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    ABSTRACT: Bismuth ferrite (BiFeO3) and Nd-doped BiFeO3 thin films have been grown on Pt/Ti/SiO2/Si substrates with pulsed laser deposition using the same growth conditions. Different resistive switching behaviours have been observed on the pure and doped BiFeO3 thin films. The leakage current is deceased after Nd doping, which benefits the fabrication of high-density resistive switching memory with low power consumption. The conduction mechanisms are discussed to understand the effect of Nd doping on the resistive switching properties of BiFeO3 thin films.
    No preview · Article · Jun 2015 · Material Research Innovations
  • J. Meng · W.-B. Luo · C.-G. Wu · X.-Y. Sun · P. Zhang · Y.-C. Yu · Y. Shuai
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    ABSTRACT: Lead magnesium niobate-lead titanate (PMN-PT) ceramic prepared by columbite precursor method and polyvinylidene fluoride-trifluoroethylene P(VDF-TrFE) have been used to fabricate 0-3 composites thick films on ITO substrates by flow casting. The phase structure of PMN-PT was analyzed by XRD and the interface of 0-3 composites was characterized by SEM. Variation of dielectric constant (εr) and electric field applied to the ceramic phase (Ec) with temperature were studied to optimize the polarization temperature. Furthermore, compared with the conventional polarization in stages, PMN-PT ceramic content effect on pyroelectric properties of composites was also discussed under optimized polarization condition. The results showed that the pyroelectric coefficient increases to 58.6 μC/(m2·K) at a ceramic mass fraction of 55% by polarizing temperature with 110℃.
    No preview · Article · Apr 2015 · Gongneng Cailiao/Journal of Functional Materials
  • Y.L. Lin · J. Zhu · Z.P. Wu · W.B. Luo · X.P. Liu · S.J. Wu · L.Z. Hao
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    ABSTRACT: Lead hafnate-titanate (PHT) thin films have been prepared via pulsed laser deposition (PLD) on Pt(1 1 1)/Ti/SiO2/Si(1 0 0) substrates by inserting a low temperature (200–400 °C) self-buffered layer. It is found that the self-buffered layers deposited at different temperatures have a great influence on the microstructure and electric properties. XRD spectra, including θ–2θ and ω scans, show that the PHT films with (1 1 1) preferred orientation were successfully deposited on substrates by inserting a low temperature self-buffered layer. Compared with the PHT films directly deposited at a high temperature, the PHT films with an inserted low temperature (300 °C) self-buffered layer have significantly enhanced electrical properties of four orders of magnitude lower leakage current density (3.2 × 10−8 A/cm2 at 150 kV/cm), 1.5 times larger remnant polarization (2Pr = 63 μC/cm2), 0.4 times smaller coercive field (2Ec = 190 kV/cm), and more excellent fatigue endurance (almost no degradation after 2 × 1010 switching cycles). The use of self-buffered layer is an effective approach to fabricate PHT ferroelectric materials with large ferroelectric polarization and long fatigue endurance.
    No preview · Article · Apr 2015 · Journal of Alloys and Compounds
  • X.Y. Sun · W.B. Luo · J. Meng · X. Qing · W.Y. Fu · Y. Shuai · C.G. Wu
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    ABSTRACT: The effects of SiO2 aerogel film thickness on the properties of pyroelectric device were studied by ANSYS thermal simulation and infrared radiation test. At first, the temperature distributions of the pyroelectric devices with different thicknesses of SiO2 aerogel film were simulated by ANSYS. After that, aerogel films with thicknesses from 300 nm to 1000 nm were deposited on Si substrates by spin coating. Thermal conductivity of SiO2 aerogel film was 2.78 × 10−2 W/mK by 3ω method test. Films were utilized in our pyroelectric infrared detectors as thermal insulators. The detectivity (D*) of these detectors were measured by mechanically chopped blackbody radiation. The D* values was enhanced as the SiO2 aerogel film thickness increased from 300 nm to 800 nm, indicating the thermal isolation effects was improved. Detector with thermal insulation layer thickness of 780 nm possessed the greatest D* over the the whole frequency range from 5.3 Hz to 133.3 Hz. The D* was above 7 × 107 cmHz1/2W−1 and reached the highest value of 9.7 × 107 cmHz1/2W−1, which represented a wide bandwidth of over 128 Hz. This result indicated that SiO2 aerogel film of 780 nm in thickness was a promising thermal isolation material for Monolithic pyroelectric infrared detectors.
    No preview · Article · Mar 2015 · Sensors and Actuators A Physical
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    ABSTRACT: BiFeO3 thin films were irradiated by Ar+ ions with different fluences. The rectifying and resistive switching behaviour were retained on the Au/BiFeO3/Pt stack, and the ON/OFF ratio clearly depends on the Ar+ fluence. It was observed that the transport in high resistance state changes from Poole-Frenkel conduction to space-charge-limited conduction after irradiation. While the conduction of the low resistance state is dominated by both the interface and the bulk thin film in the pristine devices, however, it is only dominated by the interface in the irradiated devices. The observed change of conduction mechanism was explained by additionally created oxygen vacancies (OVs) during irradiation, which also improves the stability of resistive switching.
    No preview · Article · Dec 2014 · Applied Surface Science
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    ABSTRACT: Resistive switching (RS) has been investigated in unstructured, polycrystalline BiFeO3 thin films with an emphasis on the possibility to downscale the top electrode size. Reproducible RS can be shown for large-scale top and bottom electrodes. However, distinguishable RS is observed when the top electrode is downscaled to the grain size. The microscopic conduction is found to take place within grains. We demonstrate the recovery of homogeneous RS in unstructured, polycrystalline BiFeO3 with downscaled electrodes and reduced conductive unit size by decreasing the BiFeO3 film thickness.
    Full-text · Article · Nov 2014 · Physica Status Solidi (A) Applications and Materials
  • S.-J. Wu · J. Zhu · W.-B. Luo · Z.-P. Wu · Y.-L. Lin · X.-P. Liu
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    ABSTRACT: By pulsed laser deposition (PLD), Hf0.2Zr0.8O2 (HZO) thin films were fabricated on Pt/Ti/SiO2/Si substrates under different temperatures and oxygen pressures respectively. The impact of the technical conditions on the films' structural and ferroelectric properties was studied. The films were characterized by X-ray diffraction (XRD) and Radiant RT66A. The results figured that, the ferroelectric polarization was resulted from the impact of the orthorhombic phase HfO2-ZrO2 (111) and tetragonal phase ZrO2 (002).18 Pa, 500℃ were the optimized parameters of the Hf0.2Zr0.8O2 films on Pt/Ti/SiO2/Si. On the optimized condition, the film's 2Pr was 4 μC/cm2.
    No preview · Article · Sep 2014 · Gongneng Cailiao/Journal of Functional Materials
  • C.G. Wu · P. Li · G.Q. Cai · W.B. Luo · X.Y. Sun · Q.X. Peng · W.L. Zhang
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    ABSTRACT: The fabrication method and the pyroelectric response of a single element infrared sensor based lead zirconate titanate (PZT) particles and polyvinylidene fluoride P(VDF-TrFE) copolymer composite thick film is reported in this paper. A special thermal insulation structure, including polyimide (PI) thermal insulation layer and thermal insulation tanks, was used in this device. The thermal insulation tanks were fabricated by laser micro-etching technique. Voltage responsivity (RV), noise voltage (Vnoise), noise equivalent power (NEP), and detectivity (D∗) of the PZT/P(VDF-TrFE) based infrared sensor are 1.2×103V/W, 1.25×10-6VHz1/2, 1.1×10-9W and 1.9×108cmHz1/2W-1 at 137.3 Hz modulation frequency, respectively. The thermal time constant of the infrared sensor τT was about 15ms. The results demonstrate that the composite infrared sensor show a high detectivity at high chopper frequency, which is an essential advantage in infrared detectors and some other devices.
    No preview · Article · Sep 2014 · Infrared Physics & Technology
  • C. G. Wu · P. Li · W. B. Luo · J. Meng · X. Y. Sun · Y. Shuai · W. L. Zhang
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    ABSTRACT: In this paper, a flexible pyroelectric sensor using PbZr0.3Ti0.7O3 PZT/P(VDF-TrFE) materials on the polyimide (PI) flexible printed circuit substrate was reported. The fabrication processes, material electric properties and infrared photoelectric response property of the designed sensor were studied. First, the PZT ceramic powder was annealed at temperatures ranging from 300 to 900 degrees C, and then 0-3 PZT/PVDF-TrFE composites films were produced by casting PZT/PVDF-TrFE suspension onto the flexible PI substrates. The highest pyroelectric coefficient obtained using 700 degrees C annealed PZT particulates was 96 mu C m(-2) K-1, which was 20% higher than that of unannealed powders. The PI thermal insulation layer and thermal insulation tanks fabricated by laser microetching have been used to improve the photoelectric response ability of the infrared sensor. The specific detectivity of the sensors was calculated from the voltage responsivity and noise. Detectivity D* of the PZT/P(VDF-TrFE) infrared sensor was 1.17 x 10(8) cm Hz(1/2) W-1 at 138.3 Hz modulation frequency. These results demonstrate that the pyroelectric infrared sensor possesses potential applications in flexible electronics.
    No preview · Article · May 2014 · Material Research Innovations
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    ABSTRACT: In this study, ultraviolet curing ink is used as absorber of uncooled infrared detector in the near and far wavelength infrared spectrum. The ultraviolet curing ink is patterned by lithography to meet the requirement of industrial production. The absorbance of the radiation wavelength of 320 mm is higher than 80%. Fabricated with the absorber, the infrared sensor shows voltage responsivity of 1186 V W-1 and specific detectivity of 2.6 x 10(8) cm Hz(1/2) W-1 at 5.3 Hz respectively. The detectivity of single crystal LiTaO3 substrate with absorber is around 23.6 times higher than that without it at 138.3 Hz.
    No preview · Article · May 2014 · Material Research Innovations
  • Q. X. Peng · W. B. Luo · C. G. Wu · X. Y. Sun · P. Li · X. Y. Chen
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    ABSTRACT: In this paper, the effect of surfactant polyvinylalcohol (PVA) and polyacrylate acid (PAA) on shape evolution of Pb(Zr0.3Ti0.7)O3 (PZT) nano materials synthesized by hydrothermal method was studied. PZT nanorod array was grown on the conduction substrate surface of (100) Nb–SrTiO3 with optimized PVA and PAA concentrations. X-ray diffraction, scanning electron microscopy and transmission electron microscopy were used to characterize the PZT nanomaterials. The results demonstrated that the optimization concentration of PVA and PAA were 0.8 and 3.2 g L−1, respectively. The pyroelectric coefficient of the PZT nanorod array was 1.75 × 10−9 C cm−2 K−1 before poling and 2.56 × 10−9 C cm−2 K−1 after poling. This low temperature synthesized PZT nanorod array shows great potential application in pyroelectric nanodevices.
    No preview · Article · Apr 2014 · Journal of Materials Science Materials in Electronics
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    ABSTRACT: Polycrystalline BiFeO3 thin films have been grown by pulsed laser deposition on Pt/Ti/SiO2/Si substrates. The microstructures of the thin films were characterized by X-ray-diffraction and scanning electronic microscopy. The resistive switching in BiFeO3 thin films has been systematically investigated by current-voltage measurements. It has been observed that the oxygen ambient pressure during the deposition influences the ON/OFF ratio of the switching. The substrate temperature affects the rectifying behaviour of the thin films, and consequently determines the possibility of resistive switching in BiFeO3 thin films. By varying the thickness of the thin film, it has been revealed that the switching takes place near the electrode/film interface. The mechanism of the observed resistive switching has been attributed to a charge trapping effect at the interface.
    No preview · Article · Mar 2014 · Journal of Materials Science Materials in Electronics
  • Q.X. Peng · C.G. Wu · W.B. Luo · C. Chen · G.Q. Cai · X. Y. Sun · D.P. Qian
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    ABSTRACT: In this paper, we presented a new pyroelectric detector with back to back silicon cups and micro-bridge structure. The PZT thick film shaped in the front cup was directly deposited with designed pattern by electrophoresis deposition (EPD). Pt/Ti Metal film, which was fabricated by standard photolithography and lift-off technology, was sputtered to connect the top electrode and the bonding pad. The cold isostatic press (CIP) treatment could be applied to improve the pyroelectric properties of PZT thick film. The infrared (IR) properties the CIP-optimized detector were measured. The voltage responsivity (RV) was 4.5 × 102 V/W at 5.3 Hz, the specific detectivity (D*) was greater than 6.34 × 108 cm Hz1/2 W-1 (frequency > 110 Hz), and the thermal time constant was 51 ms, respectively.
    No preview · Article · Nov 2013 · Infrared Physics & Technology
  • Q.X. Peng · C.G. Wu · W.B. Luo · L. Jin · W.L. Zhang · C. Chen · X.Y. Sun
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    ABSTRACT: The effects of TiOx diffusion barrier layer thickness on the microstructure and pyroelectric characteristics of PZT thick films were studied in this paper. The TiOx layer was prepared by thermal oxidation of Ti thin film in air and the PZT thick films were fabricated by electrophoresis deposition method (EPD). To demonstrate the barrier effect of TiOx layer, the electrode/substrate interface and Si content in PZT thick films were characterized by scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS), respectively. The TiOx barrier thickness shows significant influence on the bottom electrode and the pyroelectric performance of the PZT thick films. The average pyroelectric coefficient of PZT films deposited on 400 nm TiOx layer was about 8.94 × 10−9 C/(cm2 K), which was improved by 70% than those without diffusion barrier layer. The results showed in this study indicate that TiOx barrier layer has great potential in fabrication of PZT pyroelectric device.
    No preview · Article · May 2013 · Infrared Physics & Technology
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    ABSTRACT: SrTiO3 (STO) films have been grown on TiO2-buffered GaN(0002) substrates. The deposition process was in situ monitored by reflective high energy electron diffraction (RHEED). The deposition rate and in-plane lattice parameter of TiO2 were calculated from the oscillation curve and RHEED patterns, respectively. It was found that the TiO2 lattice parameter changed as the thickness increased, which indicated a strain relaxation process of TiO2 buffer layers during the deposition. We show that the thickness of TiO2 can significantly influence the STO growth mode, surface morphology, and crystalline quality. As the TiO2 thickness increased, the STO growth mode is changed from 3D island to 2D growth mode and finally to SK mode as revealed by RHEED. The growth mode evolution shows close relation with the surface morphology and crystalline quality of STO. STO films deposited on 2 nm thick TiO2 film show 2D growth mode and have smoothest surface and smallest full width at half maximum of the STO rocking curve. Our investigation hints towards to a general approach to optimize the crystalline quality of STO, which can be optimized by adjusting the strain state of TiO2 buffer layer.
    No preview · Article · Apr 2013 · Journal of Applied Physics
  • W B Luo · J Jing · Y Shuai · J Zhu · W L Zhang · S Zhou · S Gemming · N Du · H Schmidt
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    ABSTRACT: SrTiO3 films were grown on CeO2/YSZ/TiO2 multilayer buffered GaN/Al2O3 (0 0 0 1) substrates with and without the YBa2Cu3 O7−x (YBCO) bridge layer by pulsed laser deposition (PLD). The deposition process of the buffer layers was in situ monitored by reflection high-energy electron diffraction. The crystallographical orientation of the heterostructure was studied by x-ray diffraction (XRD). With the introduction of the YBCO (0 0 1) layer, the STO (0 0 1) film was epitaxially grown on the GaN substrate. There were three sets of inplane domains separated from each other by 30° in both STO and YBCO buffer layers. The epitaxial relationship was STO (0 0 2)[1 1 0]∥YBCO(0 0 1)[1 1 0]∥CeO2(0 0 2)[0 1 0]∥YSZ (0 0 2)[0 1 0]∥GaN(0 0 0 1)[1 1 -2 0] according to XRD results. By comparing the orientation of STO grown on GaN with and without the YBCO top buffer layer, the surface chemical bonding was found to be a very important factor in determining the orientation relationship of STO.
    No preview · Article · Jan 2013 · Journal of Physics D Applied Physics

Publication Stats

229 Citations
65.03 Total Impact Points


  • 2008-2016
    • University of Electronic Science and Technology of China
      • State Key Laboratory of Electronic Thin Films and Integrated Devices
      Hua-yang, Sichuan, China
  • 2013
    • Helmholtz-Zentrum Dresden-Rossendorf
      • Institute of Ion Beam Physics and Materials Research
      Dresden, Saxony, Germany