H. Q. Zhang

Dalian University of Technology, Lü-ta-shih, Liaoning, China

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Publications (30)29.12 Total impact

  • A.L. Zou · Y. Qiu · J.J. Yu · B. Yin · G.Y. Cao · H.Q. Zhang · L.Z. Hu
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    ABSTRACT: A room temperature ethanol sensor based on Au-modified zinc oxide microwires (Au/ZnO MWs) is demonstrated. Au nanoparticles (Au NPs) were immobilized via ion sputtering onto the surface of CVD-fabricated ZnO microwires (ZnO MWs) to serve as sensitizers. Au modification was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and photoluminescence. Gas-sensing tests indicated that the modified microwires exhibited an enhanced performance relative to the unmodified ZnO microwires over a wide gas concentration range, with very stable repeatability, fast recovery time and high sensing response and selectivity. A sensing mechanism is described in terms of localized surface plasmon resonance (LSPR) effect of Au NPs. The superior sensing characteristics indicate the device's potential applications as room-temperature gas sensor, and a straightforward and economical fabrication also makes it very attractive for more widespread use.
    No preview · Article · May 2016 · Sensors and Actuators B Chemical
  • A. L. Zou · L. Z. Hu · Y. Qiu · G. Y. Cao · J. J. Yu · L. N. Wang · H. Q. Zhang · B. Yin · L. L. Xu
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    ABSTRACT: ZnO microwires of two different cross-sectional profiles were synthesized by chemical vapor deposition, and their morphologies were characterized by scanning electron microscopy. Their cross-sectional hexagonal profile could be tuned from straight to curved sides, by regulating the ZnO:graphite powder ratio used during synthesis. The ZnO microwires had hexagonal profiles with curved sides at a higher graphite ratio, and hexagonal profiles with straight sides at a lower graphite ratio. The higher graphite ratio was speculated to lower the growth rate from center to hexagonal sides, relative to the corners. The ZnO microwires were fabricated into gas sensors, and their sensing characteristics towards ethanol gas were investigated. The sensor based on a ZnO microwire with curved sides exhibited superior ethanol sensing performance than that based on a microwire with straight sides, which was attributed to the higher surface-to-volume ratio of the curved-side microwire. The sensor based on a ZnO microwire with curved sides was stable, and exhibited rapid response and recovery times. The straight-forward and economical fabrication of the gas sensor at room temperature makes it attractive for practical application.
    No preview · Article · Jul 2015 · Journal of Materials Science Materials in Electronics
  • J. X. Lei · Y. Qiu · D. C. Yang · H. Q. Zhang · B. Yin · J. Y. Ji · Y. Zhao · L. Z. Hu
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    ABSTRACT: There are numerous sources of mechanical energy in our environment, such as ultrasonic waves, body movement, and irregular air flow/vibration. Here, we present a simple, cost-effective approach for fabricating a flexible nanogenerator and apply it to harvest energy from environmental mechanical vibrations. The nanogenerator was based on ZnO nanorods grown on common paper substrate using a low-temperature hydrothermal method. Piezoelectric currents were measured by attaching the nanogenerator on the surface of a cantilever and a wind-up drum, respectively. At the same time, the vibrations of the cantilever and wind-up drum could also be characterized by the corresponding output signals. This is a practical and versatile technology with the potential for converting a variety of environment energy into electric energy, and also with the application for pre-warning of emergency, such as earthquake and burgling.
    No preview · Article · May 2015 · Journal of Renewable and Sustainable Energy
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    ABSTRACT: In this paper, branched ZnO nanotrees (NTs) have been synthesized on flexible fiber-paper substrates by introducing a multistep hydrothermal approach for realizing high-performance piezoelectric nanogenerators. With this method, a significant enhancement in output voltage of the NGs ranging from 14 mV to 0.1 V was achieved, with a nearly 20 times enhanced power density compared to the vertically grown ZnO NWs. This is the first demonstration of fabricating branched ZnO NTs-coated fiber paper for energy harvesting devices, which may provide guidelines for designing high-performance piezoelectric energy harvesting.
    No preview · Article · Jan 2015 · RSC Advances
  • X. Liu · L.-Z. Hu · H.-Q. Zhang · Y. Qiu · Y. Zhao · Y.-M. Luo
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    ABSTRACT: Novel ZnO micro-thornyballs (TBs) were prepared by chemical vapor deposition (CVD) method. Furthermore, a novel flexible piezoelectric strain sensor based on the thorny balls was fabricated by a simple technique. The characterization of the sensor was tested by semiconductor characterization system (Keithey 4200). The sensor is highly sensitive to an applied stress and has a high on-off ratio (~60). The rusults showed that the sensor is expected to have potential applications in detection of external mechanical force, as well as electromechanical switch.
    No preview · Article · Sep 2013
  • H.q.zhang · M.han · Q.wang · G.h.wang
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    ABSTRACT: High-resolution electron microscope (HREM) and computer simulation are used to investigate structural features of gold clusters produced by the inert-gas condensation method. The results indicate that (i) smaller clusters have multiple-twinned-like structure while those larger than 150 Å in diameter show single-crystal structure; (ii) the former cluster consists of either decahedral or icosahedral form and the atomic planes are not strictly parallel and distances between the planes increase towards the cluster edge; and (iii) grain boundaries between the clusters have twin structures with both long- and short-range orders.
    No preview · Article · Jan 2012 · Surface Review and Letters
  • G.h.wang · H.q.zhang · J.x.ma · M.han · Q.wang · J.j.zhao
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    ABSTRACT: Optical absorption and laser Raman scattering spectroscopies as well as EXAFS are used to investigate the copper clusters embedded in the lithium fluoride, and the results indicate that (i) the metal clusters of about 2 nm in diameter have the bulk-like fcc structure with a contracted interatomic distance and lower mean coordination number, (ii) the embedded metal clusters show a surface-plasmon resonance, (iii) for clusters smaller than certain size the surface-phonon mode becomes important, and the high-order longitudinal phonon vibrational modes emerge.
    No preview · Article · Jan 2012 · Surface Review and Letters
  • L.N. Wang · L.Z. Hu · H.Q. Zhang · Y. Qiu · Y. Lang · G.Q. Liu · J. Y. Ji · J.X. Ma · Z.W. Zhao
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    ABSTRACT: We prepared Ag doped zinc oxide (ZnO:Ag) films using pulsed laser deposition method and studied the Raman spectra of the unannealed and annealed films. The results indicate that the ZnO:Ag films could still retain their wurtzite structure; the A1 (LO) mode resulting from oxygen vacancies and zinc interstitials was observed to be very strong in the Raman spectra. A local vibrational mode at 493cm−1 induced by Ag doping could also be clearly observed in the Raman spectra, which may be used as an indication of Ag incorporation into the ZnO lattice.
    No preview · Article · Sep 2011 · Materials Science in Semiconductor Processing
  • Y. Zeng · M. Bao · J.-X. Ma · H.-J. Chen · G.-Y. Zhang · H.-Q. Zhang
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    ABSTRACT: Aim: To study the immunoregulatory mechanisms of the total flavonoids of Tibetan herb Myricaria germanica auct. non Linn. Desv. in adjuvant arthritic rats. Methods: Freund's complete adjuvant (FCA) was used to induce AA in rats. Secondary paw swelling of AA rats was measured with volume meter and the immune organ weight was explored. Proliferation and transformation of spleen lymphocytes induced by ConA were determined by MTT method. Phagocytosis of peritoneal macrophages was tested by neutral red test. IL-2 and TNF-α productions of AM were estimated by enzyme linked immuno sorbent assay (ELISA). Results: The secondary inflammation of AA rats appeared on the 12th day after injection of FCA. At the same time, the total flavonoids of Tibetan herb Myricaria germanica auct. non Linn. Desv. and Indomethacin were given to AA rats by intragastric administration for two weeks. The total flavonoids of Tibetan herb Myricaria germanica auct. non Linn. Desv. (1.0, 1.5 g·kg -1) could significantly inhibit secondary inflammatory reaction of AA rats from the 24th day. The total flavonoids of Tibetan herb Myricaria germanica auct. non Linn. Desv. could reduce the thymus index and TNF-α content. Meanwhile, the total flavonoids of Tibetan herb Myricaria germanica auct. non Linn. Desv. could remarkably improve the transformation of spleen lymphocytes, phagocytosis of peritoneal macrophages and the the IL-2 content. Conclusions: The total flavonoids of Tibetan herb Myricaria germanica auct. non Linn. Desv. has therapeutical effect on AA rats. Its mechanisms may be through improving the capability of cell-mediated immunity in AA rats.
    No preview · Article · Apr 2011 · Chinese Pharmacological Bulletin
  • Y. Qiu · L.Z. Hu · D.Q. Yu · H.Q. Zhang · J.C. Sun · B. Wang · J.X. Ma · L.N. Wang · K.T. Sun · Z.W. Zhao
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    ABSTRACT: A tail-like cluster composed of zinc oxide (ZnO) microwires had been synthesised by a simple chemical vapour deposition method at high temperature. Most of the microwires exhibit an interesting gear-shaped microstructure. A new model is proposed to interpret the growth mechanism of gear-shaped ZnO microwires. It is suggested that the gear-shaped ZnO microwires are formed by a coalescence of ZnO fine wires. A distinct ultraviolet emission band centred at 389.8 nm is observed in the photoluminescence spectrum. The gear-shaped microwires with high surface-to-volume ratio are expected to improve the physical, chemical and biological sensitivity of ZnO, which will be helpful for the further application of ZnO in the field of sensor devices.
    No preview · Article · Nov 2010 · Micro & Nano Letters
  • B. Wang · Z.-W. Zhao · Y. Qiu · J.-X. Ma · H.-Q. Zhang · L.-Z. Hu
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    ABSTRACT: ZnO thin films were deposited on Al2O3(001)substrates by megnetron sputtering method at 500°C, 550°C, 600°C and 650°C, respectively. The as-deposited ZnO films samples were annealed at 800°C and 1000°C. The structure, electrical and optical properties of the ZnO thin films were investigated by X-ray diffraction(XRD), Hall and transmittance spectrum measurements. The results indicated that crystalline quality, electrical and optical properties could be highly improved by proper growth temperature and annealing temperature.
    No preview · Article · Oct 2010 · Rengong Jingti Xuebao/Journal of Synthetic Crystals
  • K.-T. Sun · L.-Z. Hu · D.-Q. Yu · J. Li · H.-Q. Zhang · Q. Fu · X. Chen · B. Wang
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    ABSTRACT: One-dimensional (1D) semiconducting nanomaterials have attracted considerable interest for their potential applications in optoelectronic and microelectronic devices. Among thoses 1D semiconducting nanomaterials, ZnO is a wide band gap semiconductor and one of the most functional materials. On account of its many interesting properties, such as superior emission, chemical and thermal stability, transparency, biocompatibility, and wide electrical conductivity range, ZnO has a variety of applications in an emerging area of nanotechnology. Moreover, as a very important one of ZnO nanostructure groups, ZnO nanorods(NRs) have wide applications in nanoelectronics including nanobased light-emitting diodes (LEDs), field effect transistors (FETs), ultraviolet (UV) lasers, and nanogenerators. Until now, there are numerous experimental methods to prepare ZnO NRs involving molecular beam epitaxy (MBE), sputtering, electrochemical deposition, vapor phase transport (VPT), chemical vapor deposition (CVD), and thermal evaporation. However, most of these attempts need some kind of metals to act as a catalyzer. Aurum, zinc, argentine, and aluminium are often used in these methods, which make the prepared ZnO NRs impure. In the cases the metallic impurities have awful influence on the electrical and optical properties of ZnO NRs, an advanced and catalyst-free ZnO growth method needs to be exploited.In this paper, ZnO NRs were successfully synthesized on indium phosphide (InP) (100) substrates by using pulsed laser deposition (PLD) method with catalyst-free. The morphology, crystal structural and optical properties were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL) analytic approaches, respectively. SEM pattern showed the ZnO nanorods were well-oriented. From the XRD scan results, a strong peak was observed at 34.10° attributed to the ZnO (002) face, indicating that the growth direction is well-oriented along c axis. A typical PL spectrum was measured at room temperature, showing a strong free-excition emission at about 379 nm, with full width at half maximum (FWHM) value of 19 nm, no deep level emission was detected, indicating that the ZnO nanorods produced in this experiment are of high optical quality.
    No preview · Article · Apr 2010
  • D.Q. Yu · L.Z. Hu · J. Li · H. Hu · H.Q. Zhang · J.M. Bian · J.X. Zhu · S.S. Qiao · X. Chen · B. Wang
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    ABSTRACT: Phosphorus-doped ZnO nanoneedle arrays were prepared by phosphorus diffusion from InP substrate using a pulsed laser deposition (PLD) technique. The optical properties of ZnO nanoneedle were investigated by photoluminescence (PL) spectroscopy. Low-temperature photoluminescence spectrum measurements exhibited five acceptor-related emission peaks. The excitation intensity and temperature dependent photoluminescence spectra confirmed that the emission peaks corresponded to neutral-acceptor bound exciton, free electron to acceptor, donor–acceptor pairs, and their first and second photon replicas transitions. Acceptor-binding energy was determined to be 135–167meV, which agrees well with the best-fitting result of the temperature dependent photoluminescence measurements and is reasonable in terms of theoretic prediction in ZnO.
    No preview · Article · Feb 2009 · Applied Surface Science
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    ABSTRACT: A growing and etching technique for GaAs microtips is introduced, which could be used for scanning electron microscopy (SEM) images Liquid-phase epitaxy (LPE) is used to fabricate GaAs periodic microtip array through SiO2 mask windows. AlGaAs layer is grown between GaAs substrate and GaAs microtips, and then the AlGaAs layer is selectively etched, which leads to the GaAs microtips peeling off from the substrate. SEM images show that the transferred GaAs microtips have the micro-pyramid structure with sharp tops and smooth surfaces, and they are not damaged during the transfer process. The shapes of the GaAs microtips fabricated by this technique are mainly decided by the crystal structure, and they have the superiority of repetition, smooth surface and suitability for mass production.
    No preview · Article · Nov 2008 · Guangdianzi Jiguang/Journal of Optoelectronics Laser
  • J Z Zhao · H W Liang · J C Sun · J M Bian · Q J Feng · L Z Hu · H Q Zhang · X P Liang · Y M Luo · G T Du
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    ABSTRACT: An n-ZnO/p-ZnO : Sb homojunction light emitting diode was fabricated on c-plane sapphire by metal–organic chemical vapour deposition (MOCVD). The p-type ZnO layer with a hole concentration of 1.27 × 1017 cm−3 was fabricated using trimethylantimony (TMSb) as the Sb doping source. The current–voltage characteristics of the device exhibited a desirable rectifying behaviour with a turn-on voltage of 3.3 V. Distinct electroluminescence with ultraviolet and visible emissions was detected from this device under forward bias at room temperature. Moreover, metal–organic source TMSb is an effective and controllable dopant in the MOCVD technique, which is suitable for further industrialized production.
    No preview · Article · Sep 2008 · Journal of Physics D Applied Physics
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    ABSTRACT: ZnO homojunction light emitting device (LED) with n-ZnO:Ga/p-ZnO:N structure was fabricated on sapphire substrate by metal organic chemical vapor deposition. The reproducible p-type ZnO:N layer with hole concentration of 1.29 × 1017 cm−3 was formed with NH3 as N doping source followed by thermal annealing in N2O plasma protective ambient. The device exhibited desirable rectifying behavior. Distinct electroluminescence emission centered at 3.2 eV and 2.4 eV were detected from this device under forward bias at room temperature. The intensive ultraviolet emission was comparable to the visible emission in the electroluminescence spectrum, which represent remarkable progress in the performance of ZnO homojunction LED.
    No preview · Article · Jul 2008 · Chemical Physics Letters
  • D.-Q. Yu · J. Li · H. Hu · J.-C. Sun · H.-Q. Zhang · Z.-W. Zhao · Q. Fu · G.-T. Du · L.-Z. Hu
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    ABSTRACT: In recent years, semiconductor nanostructures have attracted much attention due to their potential application in a wide range of advanced devices. ZnO nanostructure has become a promising candidate for applications in functional oxide-based, blue-ultraviolet light emitting, field-effect transistor and transparent conductivity, because of its large direct wide band gap of 3. 37 eV and large exciton binding energy of 60 meV. Furthermore, ZnO nanostructure can be used for electromechanical coupled sensor, transducers and biomedical applications. Many researchers reported the synthesis of ZnO nanostructures by a vapor-liquid-solid (VLS) mechanism. This approach is the most widely used technique for synthesizing aligned ZnO nanostructures, in which the assistance of metal catalysts, such as Au, Co, Cu etc. are frequently chosen. Because these catalysts commonly are also unfavorable impurities in the product, so it is necessary to exploit some catalyst-free growth techniques of ZnO nanostructures. Most of the related works were focused on the silicon and sapphire substrates using VLS technique, however there was no report of catalyst-free fabricating ZnO nano-structure on InP using pulsed laser deposition (PLD) technique. In this paper, we employed InP wafers as the substrates, a undoped thin ZnO film with thickness of 20-30 nm was predeposited on InP substrate surface by PLD as the buffer layer. The predeposited ZnO film assembled uniform ZnO islands on the InP substrate surface. ZnO nanoneedle-type nanostructure were successfully synthesized on indium phosphide (InP) (100) substrates. It illuminates that the using of catalyst is not absolutely necessary in the growth of ZnO nanostructures. The morphologic, crystal structural and optical properties were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL) spectrum analytic approaches, respectively. SEM pattern showed that the ZnO nanoneedle was obtained in high yield and high-quality and had a preferential growth orientation that was perpendicular to the substrate surface and are well separated from each other. From the XRD scan results, a strong diffraction peak was observed at 34.5°, attributing to the ZnO (002) plane, indicating that the growth direction is well-oriented along c-axis and has highly crystalline quality. A typical PL spectrum, measured at room temperature, showed a strong free-excition emission at 379 nm with a full width at half maximum (FWHM) value of 13.5 nm, and a weak deep level (DL) emission at 484 nm, the intensity ratio of free-excition emission relative to DL emission was 11:1, indicating that the ZnO nanoneedles produced in this experiment are of high optical quality. The simple and efficient method to fabricate ZnO nanoneedle has the following advantages: low cost, potential for wafer-scale production, and guaranteeing high-purity of ZnO. Therefore, this method may benefit in the applications for nano-devices.
    No preview · Article · Jun 2008 · Chinese Journal of Luminescence
  • H W Liang · Q J Feng · J C Sun · J Z Zhao · J M Bian · L Z Hu · H Q Zhang · Y M Luo · G T Du
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    ABSTRACT: ZnO film was grown on a heavily phosphor-doped n+-Si substrate by metal–organic chemical vapor deposition technology. X-ray photoelectron spectroscopy measurements indicate that a two-layer structure, comprised of a phosphor-doped ZnO layer and an un-doped ZnO layer, was formed during the diffusion process of phosphor from the n+-Si substrate. The current–voltage characteristic exhibited significant rectifying behavior with low-leakage current for this device. The distinct defect-related blue–white electroluminescence was observed, the origin of which was confirmed to be from the ZnO p–n homojunction.
    No preview · Article · Jan 2008 · Semiconductor Science and Technology
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    ABSTRACT: Reproducible p-type Sb-doped ZnO thin films were fabricated on c-plane sapphire substrates by the metallorganic chemical vapor deposition (MOCVD) technique using trimethylantimony as the doping precursor. Sb was introduced into ZnO thin films as a p-type dopant without any phase separation. Obvious donor-acceptor pair emissions were observed from photoluminescence spectra of ZnO:Sb films at 10 K. The acceptor binding energy is estimated to be similar to 124 meV. Using the metallorganic source as the dopant of p-type ZnO thin films by the MOCVD technique is beneficial for the industrialized production of ZnO light-emitting diodes.
    No preview · Article · Jan 2008 · Electrochemical and Solid-State Letters
  • X. Chen · H. Q. Zhang · L. Z. Hu · D. Q. Yu · Z. W. Zhao · S. S. Qiao · J. Li · J. X. Zhu
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    ABSTRACT: CdSxSe1-x quantum dots (QDs) were prepared on silicon substrate by a simple physical method. The temperature dependent photoluminescence (PL) properties of the CdSxSe1-x QDs have been investigated in a temperature range of 10-300 K. The PL intensity reveals an unusual increasing behaviour with increasing temperature in the range of 180 - 260 K. And the energy gap shows a redshift of 62.23 meV when the temperature increases from 10 K to 300 K. The sulfur component (x) of CdSxSe1-x QDs is about 86.45% by calculation approximatively from PL peak energy at room temperature following Vigo¿s Law. We also obtain the parameters of the varshni relation for CdSxSe1-x QDs from PL peak energy as a function of temperature and the best-fit curve.
    No preview · Article · Jan 2008