Self-destructing chips have promising applications for securing data.This paper proposes a new concept of energetic diodes for the first time,which can be used for self-destructive chips.A simple two-step electrochemi...Self-destructing chips have promising applications for securing data.This paper proposes a new concept of energetic diodes for the first time,which can be used for self-destructive chips.A simple two-step electrochemical deposition method is used to prepare ZnO/CuO/Al energetic diode,in which N-type ZnO and P-type CuO are constricted to a PN junction.This paper comprehensively discusses the material properties,morphology,semiconductor characteristics,and exploding performances of the energetic diode.Experimental results show that the energetic diode has typical rectification with a turn-on voltage of about 1.78 V and a reverse leakage current of about 3×10^(-4)A.When a constant voltage of 70 V loads to the energetic diode in the forward direction for about 0.14 s or 55 V loads in the reverse direction for about 0.17 s,the loaded power can excite the energetic diode exploding and the current rises to about100 A.Due to the unique performance of the energetic diode,it has a double function of rectification and explosion.The energetic diode can be used as a logic element in the normal chip to complete the regular operation,and it can release energy to destroy the chip accurately.展开更多
Energetic Semiconductor bridge(ESCB)based on reactive multilayered films(RMFs)has a promising application in the miniature and intelligence of initiator and pyrotechnics device.Understanding the ignition enhancement m...Energetic Semiconductor bridge(ESCB)based on reactive multilayered films(RMFs)has a promising application in the miniature and intelligence of initiator and pyrotechnics device.Understanding the ignition enhancement mechanism of RMFs on semiconductor bridge(SCB)during the ignition process is crucial for the engineering and practical application of advanced initiator and pyrotechnics devices.In this study,a one-dimensional(1D)gas-solid two-phase flow ignition model was established to study the ignition process of ESCB to charge particles based on the reactivity of Al/MoO_(3) RMFs.In order to fully consider the coupled exothermic between the RMFs and the SCB plasma during the ignition process,the heat release of chemical reaction in RMFs was used as an internal heat source in this model.It is found that the exothermal reaction in RMFs improved the ignition performance of SCB.In the process of plasma rapid condensation with heat release,the product of RMFs enhanced the heat transfer process between the gas phase and the solid charge particle,which accelerated the expansion of hot plasma,and heated the solid charge particle as well as gas phase region with low temperature.In addition,it made up for pressure loss in the gas phase.During the plasma dissipation process,the exothermal chemical reaction in RMFs acted as the main heating source to heat the charge particle,making the surface temperature of the charge particle,gas pressure,and gas temperature rise continuously.This result may yield significant advantages in providing a universal ignition model for miniaturized ignition devices.展开更多
In order to further improve the catalytic performance of zeolite catalyst for methanol to aromatics(MTA)technology, the double-tier SAPO-34/ZSM-5/quartz composite zeolite films were successfully synthesized via hydrot...In order to further improve the catalytic performance of zeolite catalyst for methanol to aromatics(MTA)technology, the double-tier SAPO-34/ZSM-5/quartz composite zeolite films were successfully synthesized via hydrothermal crystallization. The Si/Al ratio of SAPO-34 film was used as the only variable to study this material. The composite zeolite material with 0.6Si/Al ratio of SAPO-34 has the largest mesoporous specific surface area and the most suitable acid distribution. The catalytic performance for the MTA process showed that 0.6-SAPO-34/ZSM-5/quartz film has as high as 50.3% benzene-toluenexylene selectivity and 670 min lifetime. The MTA reaction is carried out through the path we designed to effectively avoid the hydrocarbon pool circulation of ZSM-5 zeolite, so as to improve the aromatics selectivity and inhibit the occurrence of deep side reactions to a great extent. The coke deposition behavior was monitored by thermogravimetric analysis and gas chromatograph/mass spectrometer, it is found that with the increase of Si/Al ratio, the active intermediates changed from low-substituted methylbenzene to high-substituted methylbenzene, which led to the rapid deactivation of the catalyst. This work provides a possibility to employ the synergy effect of composite zeolite film synthesizing anti-carbon deposition catalyst in MTA reaction.展开更多
This paper reports that ion implantation to a dose of 1 ×10^17 ions/cm^2 was performed on c-axis-orientated ZnO thin films deposited on (0001) sapphire substrates by the sol-gel technique. After ion implantatio...This paper reports that ion implantation to a dose of 1 ×10^17 ions/cm^2 was performed on c-axis-orientated ZnO thin films deposited on (0001) sapphire substrates by the sol-gel technique. After ion implantation, the as-implanted ZnO films were annealed in argon ambient at different temperatures from 600 - 900 ℃. The effects of ion implantation and post-implantation annealing on the structural and optical properties of the ZnO films were investigated by x-ray diffraction (XRD), photoluminescence (PL). It was found that the intensities of (002) peak and near band edge (NBE) exitonic ultraviolet emission increased with increasing annealing temperature from 600- 900 ℃. The defect related deep level emission (DLE) firstly increased with increasing annealing temperature from 600 - 750 ℃, and then decreased quickly with increasing annealing temperature. The recovery of the intensities of NBE and DLE occurs at ~850℃ and ~750℃ respectively. The relative PL intensity ratio of NBE to DLE showed that the quality of ZnO films increased continuously with increasing annealing temperature from 600 - 900 ℃.展开更多
ZnO thin films were deposited on Si(111) substrates through a radio frequency (rf) magnetron sputtering system. Then the samples were annealed at different temperatures in air ambience and ammonia ambience respect...ZnO thin films were deposited on Si(111) substrates through a radio frequency (rf) magnetron sputtering system. Then the samples were annealed at different temperatures in air ambience and ammonia ambience respectively. The structure and composition of the ZnO films were studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The morphology of the samples was studied by scanning electron microscopy (SEM). Measured results show that ZnO films with hexagonal wurtzite structure were grown on Si(111) substrates when annealed in the two ambiences. The volatilization process of ZnO in the ammonia ambience at high temperature was discussed and the mechanism of the reaction was analyzed.展开更多
To obtain high transmittance and low resistivity ZnO transparent conductive thin films,a series of ZnO ceramic targets(ZnO:Al,ZnO:(Al,Dy),ZnO:(Al,Gd),ZnO:(Al,Zr),ZnO:(Al,Nb),and ZnO:(Al,W)) were fabr...To obtain high transmittance and low resistivity ZnO transparent conductive thin films,a series of ZnO ceramic targets(ZnO:Al,ZnO:(Al,Dy),ZnO:(Al,Gd),ZnO:(Al,Zr),ZnO:(Al,Nb),and ZnO:(Al,W)) were fabricated and used to deposit thin films onto glass substrates by radio frequency(RF) magnetron sputtering.X-ray diffraction(XRD) analysis shows that the films are polycrystalline fitting well with hexagonal wurtzite structure and have a preferred orientation of the(002) plane.The transmittance of above 86% as well as the lowest resistivity of 8.43 × 10^-3 Ω·cm was obtained.展开更多
This paper reports a piezoelectric nanogenerator(NG) with a thickness of approximately 80 μm for miniaturized self-powered acceleration sensors. To deposit the piezoelectric zinc oxide(ZnO) thin film, a magnetron spu...This paper reports a piezoelectric nanogenerator(NG) with a thickness of approximately 80 μm for miniaturized self-powered acceleration sensors. To deposit the piezoelectric zinc oxide(ZnO) thin film, a magnetron sputtering machine was used. Polymethyl methacrylate(PMMA) and aluminum-doped zinc oxide(AZO) were used as the insulating layer and the top electrode of the NG, respectively. The experimental results show that the ZnO thin films annealed at 150℃ exhibited the highest crystallinity among the prepared films and an optical band gap of 3.24 eV. The NG fabricated with an AZO/PMMA/ZnO/stainless steel configuration exhibited a higher output voltage than the device with an AZO/ZnO/PMMA/stainless steel configuration. In addition, the annealing temperature affected the open-circuit voltage of the NGs;the output voltage reached 3.81 V when the annealing temperature was 150℃. The open-circuit voltage of the prepared self-powered accelerometer increased linearly with acceleration. In addition, the small NG-based accelerometer, which exhibited excellent fatigue resistance, can be used for acceleration measurements of small and lightweight devices.展开更多
Propagation characteristics of surface acoustic waves(SAWs) in ZnO films/glass substrates are theoretically investigated by the three-dimensional(3D) finite element method. At first, for(11ˉ20) ZnO films/glass ...Propagation characteristics of surface acoustic waves(SAWs) in ZnO films/glass substrates are theoretically investigated by the three-dimensional(3D) finite element method. At first, for(11ˉ20) ZnO films/glass substrates, the simulation results confirm that the Rayleigh waves along the [0001] direction and Love waves along the [1ˉ100] direction are successfully excited in the multilayered structures. Next, the crystal orientations of the ZnO films are rotated, and the influences of ZnO films with different crystal orientations on SAW characterizations, including the phase velocity, electromechanical coupling coefficient, and temperature coefficient of frequency, are investigated. The results show that at appropriate h/λ, Rayleigh wave has a maximum k^2 of 2.4% in(90°, 56.5°, 0°) ZnO film/glass substrate structure; Love wave has a maximum k^2 of 3.81% in(56°, 90°, 0°) ZnO film/glass substrate structure. Meantime, for Rayleigh wave and Love wave devices, zero temperature coefficient of frequency(TCF) can be achieved at appropriate ratio of film thickness to SAW wavelength. These results show that SAW devices with higher k^2 or lower TCF can be fabricated by flexibly selecting the crystal orientations of ZnO films on glass substrates.展开更多
This paper reports the induced growth of high quality ZnO thin film by crystallized amorphous ZnO. Firstly amorphous ZnO was prepared by solid-state pyrolytic reaction, then by taking crystallized amorphous ZnO as see...This paper reports the induced growth of high quality ZnO thin film by crystallized amorphous ZnO. Firstly amorphous ZnO was prepared by solid-state pyrolytic reaction, then by taking crystallized amorphous ZnO as seeds (buffer layer), ZnO thin films have been grown in diethyene glycol solution of zinc acetate at 80 ℃. X-ray Diffraction curve indicates that the films were preferentially oriented [001] out-of-plane direction of the ZnO. Atomic force microscopy and scanning electron microscopy were used to evaluate the surface morphology of the ZnO thin film. Photoluminescence spectrum exhibits a strong ultraviolet emission while the visible emission is very weak. The results indicate that high quality ZnO thin film was obtained.展开更多
The effect of different annealing temperatures on the structure, morphology,and optical properties of ZnO thin films prepared by the chelating sol-gel method was investigated.Zinc-oxide thin films were coated on quart...The effect of different annealing temperatures on the structure, morphology,and optical properties of ZnO thin films prepared by the chelating sol-gel method was investigated.Zinc-oxide thin films were coated on quartz glass substrates by dip coating. Zinc nitrate, absoluteethanol, and citric acid were used as precursor, solvent, and chelating agent, respectively. Theresults show that ZnO films derived from zinc-citrate have lower crystallization temperature (below400℃), and that the crystal structure is wurtzite. The films, treated over 500℃, consist ofnano-particles and show to be porous at 600℃. The particle size of the film increases with theincrease of the annealing temperature. The largest particle size is 60 nm at 600℃. The opticaltransmittances related to the annealing temperatures become 90% higher in the visible range. Thefilm shows a starting absorption at 380 nm, and the optical band-gap of the thin film (fired at500℃) is 3.25 eV and close to the intrinsic band-gap of ZnO (3.2 eV).展开更多
Zn1-xMgxO (x = 0, 0.18) thin films were fabricated on the copper substrates by radiofrequency magnetron sputtering using the high pure argon as a sputtering gas. The Zn1-xMgxO films were characterized by X-ray powde...Zn1-xMgxO (x = 0, 0.18) thin films were fabricated on the copper substrates by radiofrequency magnetron sputtering using the high pure argon as a sputtering gas. The Zn1-xMgxO films were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and galvanostatic tests. The electrochemical test showed an improved electrochemical performance of Zn0.82EMg0.18O thin film as an anode material for lithium ion batteries.展开更多
ZnO thin films co-doped with A1 and Sb with different concentrations and a fixed molar ratio of AlCl3 to SbCl3 at 1:2, are prepared by a sol-gel spin-coating method on glass annealed at 550 ℃ for 2 h in air. The x-r...ZnO thin films co-doped with A1 and Sb with different concentrations and a fixed molar ratio of AlCl3 to SbCl3 at 1:2, are prepared by a sol-gel spin-coating method on glass annealed at 550 ℃ for 2 h in air. The x-ray diffraction results confirm that the ZnO thin films co-doped with Al distortion, and the biaxial stresses are 1.03× 10^8. 3.26× 10^8 and Sb are of wurtzite hexagonal ZnO with a very small 5.23 × 10^8, and 6.97× 10^8 Pa, corresponding to those of the ZnO thin films co-doped with Al and Sb in concentrations of 1.5, 3.0, 4.5, 6.0 at% respectively. The optical properties reveal that the ZnO thin films co-doped with Al and Sb have obviously enhanced transmittance in the visible region. The electrical properties show that ZnO thin film co-doped with Al and Sb in a concentration of 1.5 at% has a lowest resistivity of 2.5 Ω·cm.展开更多
Aluminium doped ZnO thin films(ZnO︰Al) were deposited on transparent polymer substrates at room temperature by rf magnetron sputtering method from a ZnO target with Al2O3 of 2.0 wt%. Argon gas pressure varied from ...Aluminium doped ZnO thin films(ZnO︰Al) were deposited on transparent polymer substrates at room temperature by rf magnetron sputtering method from a ZnO target with Al2O3 of 2.0 wt%. Argon gas pressure varied from 0.5 Pa to 2.5 Pa with radio frequency power of 120 W. XRD results showed that all the ZnO︰Al films had a polycrystalline hexagonal structure and a (002) preferred orientation with the c-axis perpendicular to the substrate. The grain sizes of the films were 6.3-14.8 nm.SEM images indicated the ZnO︰Al film with low Argon gas pressure was denser and the deposition rate of the films depended strongly on the Argon gas pressure, increasing firstly and then decreasing with increasing the pressure. The highest deposition rate was 5.2 nm/min at 1 Pa. The optical transmittance of the ZnO︰Al films increased and the blue shift of the absorption edge appeared when the Argon gas pressure increased. The highest transmittance of obtained ZnO︰Al films at 2.5 Pa was about 85% in the visible region. The electrical properties of the films were worsened with the increase of the Argon gas power from 1 Pa to 2.5 Pa. The resistivity of obtained film at 1.0 Pa was 2.79×10-2 Ω·cm.展开更多
The orientation of the nano-columnar ZnO films grown on sapphire using the technique of metal-organic chemical vapor deposition (MOCVD) exhibits deviation because of the mismatch between the crystal lattices of the ...The orientation of the nano-columnar ZnO films grown on sapphire using the technique of metal-organic chemical vapor deposition (MOCVD) exhibits deviation because of the mismatch between the crystal lattices of the films and the sapphire substrate. A high-throughout X-ray diffraction method was employed to determine the crystal orientation of the ZnO films at a time scale of the order of minutes based on the general area detection diffraction system (GADDS). This rapid, effective, and ready method, adapted for characterizing the orientation of the nano-columnar crystals is used to directly explain the results of observation of the X-ray diffraction images, by the measurements of the orientations of the crystal columns of the ZnO films along c-axis and in parallel to ab plane.展开更多
ZnO thin films were deposited on n-Si (111) at various substrate temperatures by pulsed laser deposition (PLD). X-ray diffraction (XRD), photoluminescence (PL), Fourier transform infrared spectrophotometer (F...ZnO thin films were deposited on n-Si (111) at various substrate temperatures by pulsed laser deposition (PLD). X-ray diffraction (XRD), photoluminescence (PL), Fourier transform infrared spectrophotometer (FTIR), and scanning electron microscopy (SEM) were used to analyze the structure, morphology, and optical property of the ZnO thin films. An optimal crystallized ZnO thin film was obtained at the substrate temperature of 600℃. A blue shift was found in PL spectra due to size confinement effect as the grain sizes decreased. The surfaces of the ZnO thin films were more planar and compact as the substrate temperature increased.展开更多
Indium-doped ZnO thin films are deposited on quartz glass slides by RF magnetron sputtering at ambient temperature. The as-deposited films are annealed at different temperatures from 400℃ to 800 ℃ in air for 1 h. Tr...Indium-doped ZnO thin films are deposited on quartz glass slides by RF magnetron sputtering at ambient temperature. The as-deposited films are annealed at different temperatures from 400℃ to 800 ℃ in air for 1 h. Transmittance spectra are used to determine the optical parameters and the thicknesses of the films before and after annealing using a nonlinear programming method, and the effects of the annealing temperatures on the optical parameters and the thickness are investigated. The optical band gap is determined from the absorption coefficient. The calculated results show that the film thickness and optical parameters both increase first and then decrease with increasing annealing temperature from 400℃ to 800℃. The band gap of the as-deposited ZnO:In thin film is 3.28 eV, and it decreases to 3.17 eV after annealing at 400℃. Then the band gap increases from 3.17 eV to 3.23 eV with increasing annealing temperature from 400℃ to 800℃.展开更多
基金the National Natural Science Foundation of China(Grant Nos.22275092,52372084)the Fundamental Research Funds for the Central Universities(Grant No.30923010920)。
文摘Self-destructing chips have promising applications for securing data.This paper proposes a new concept of energetic diodes for the first time,which can be used for self-destructive chips.A simple two-step electrochemical deposition method is used to prepare ZnO/CuO/Al energetic diode,in which N-type ZnO and P-type CuO are constricted to a PN junction.This paper comprehensively discusses the material properties,morphology,semiconductor characteristics,and exploding performances of the energetic diode.Experimental results show that the energetic diode has typical rectification with a turn-on voltage of about 1.78 V and a reverse leakage current of about 3×10^(-4)A.When a constant voltage of 70 V loads to the energetic diode in the forward direction for about 0.14 s or 55 V loads in the reverse direction for about 0.17 s,the loaded power can excite the energetic diode exploding and the current rises to about100 A.Due to the unique performance of the energetic diode,it has a double function of rectification and explosion.The energetic diode can be used as a logic element in the normal chip to complete the regular operation,and it can release energy to destroy the chip accurately.
基金supported by the National Natural Science Foundation of China(Grant Nos.22275092,52102107 and 52372084)the Fundamental Research Funds for the Central Universities(Grant No.30923010920)。
文摘Energetic Semiconductor bridge(ESCB)based on reactive multilayered films(RMFs)has a promising application in the miniature and intelligence of initiator and pyrotechnics device.Understanding the ignition enhancement mechanism of RMFs on semiconductor bridge(SCB)during the ignition process is crucial for the engineering and practical application of advanced initiator and pyrotechnics devices.In this study,a one-dimensional(1D)gas-solid two-phase flow ignition model was established to study the ignition process of ESCB to charge particles based on the reactivity of Al/MoO_(3) RMFs.In order to fully consider the coupled exothermic between the RMFs and the SCB plasma during the ignition process,the heat release of chemical reaction in RMFs was used as an internal heat source in this model.It is found that the exothermal reaction in RMFs improved the ignition performance of SCB.In the process of plasma rapid condensation with heat release,the product of RMFs enhanced the heat transfer process between the gas phase and the solid charge particle,which accelerated the expansion of hot plasma,and heated the solid charge particle as well as gas phase region with low temperature.In addition,it made up for pressure loss in the gas phase.During the plasma dissipation process,the exothermal chemical reaction in RMFs acted as the main heating source to heat the charge particle,making the surface temperature of the charge particle,gas pressure,and gas temperature rise continuously.This result may yield significant advantages in providing a universal ignition model for miniaturized ignition devices.
基金supported by the National Natural Science Foundation of China (51974312, 51974308)the National Key Research & Development Program of China (2019YFE0100100)。
文摘In order to further improve the catalytic performance of zeolite catalyst for methanol to aromatics(MTA)technology, the double-tier SAPO-34/ZSM-5/quartz composite zeolite films were successfully synthesized via hydrothermal crystallization. The Si/Al ratio of SAPO-34 film was used as the only variable to study this material. The composite zeolite material with 0.6Si/Al ratio of SAPO-34 has the largest mesoporous specific surface area and the most suitable acid distribution. The catalytic performance for the MTA process showed that 0.6-SAPO-34/ZSM-5/quartz film has as high as 50.3% benzene-toluenexylene selectivity and 670 min lifetime. The MTA reaction is carried out through the path we designed to effectively avoid the hydrocarbon pool circulation of ZSM-5 zeolite, so as to improve the aromatics selectivity and inhibit the occurrence of deep side reactions to a great extent. The coke deposition behavior was monitored by thermogravimetric analysis and gas chromatograph/mass spectrometer, it is found that with the increase of Si/Al ratio, the active intermediates changed from low-substituted methylbenzene to high-substituted methylbenzene, which led to the rapid deactivation of the catalyst. This work provides a possibility to employ the synergy effect of composite zeolite film synthesizing anti-carbon deposition catalyst in MTA reaction.
文摘This paper reports that ion implantation to a dose of 1 ×10^17 ions/cm^2 was performed on c-axis-orientated ZnO thin films deposited on (0001) sapphire substrates by the sol-gel technique. After ion implantation, the as-implanted ZnO films were annealed in argon ambient at different temperatures from 600 - 900 ℃. The effects of ion implantation and post-implantation annealing on the structural and optical properties of the ZnO films were investigated by x-ray diffraction (XRD), photoluminescence (PL). It was found that the intensities of (002) peak and near band edge (NBE) exitonic ultraviolet emission increased with increasing annealing temperature from 600- 900 ℃. The defect related deep level emission (DLE) firstly increased with increasing annealing temperature from 600 - 750 ℃, and then decreased quickly with increasing annealing temperature. The recovery of the intensities of NBE and DLE occurs at ~850℃ and ~750℃ respectively. The relative PL intensity ratio of NBE to DLE showed that the quality of ZnO films increased continuously with increasing annealing temperature from 600 - 900 ℃.
基金This work was financially supported by the Key Research Program of National Natural Science Foundation of China (Nos.90301002 and 90201025).
文摘ZnO thin films were deposited on Si(111) substrates through a radio frequency (rf) magnetron sputtering system. Then the samples were annealed at different temperatures in air ambience and ammonia ambience respectively. The structure and composition of the ZnO films were studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The morphology of the samples was studied by scanning electron microscopy (SEM). Measured results show that ZnO films with hexagonal wurtzite structure were grown on Si(111) substrates when annealed in the two ambiences. The volatilization process of ZnO in the ammonia ambience at high temperature was discussed and the mechanism of the reaction was analyzed.
文摘To obtain high transmittance and low resistivity ZnO transparent conductive thin films,a series of ZnO ceramic targets(ZnO:Al,ZnO:(Al,Dy),ZnO:(Al,Gd),ZnO:(Al,Zr),ZnO:(Al,Nb),and ZnO:(Al,W)) were fabricated and used to deposit thin films onto glass substrates by radio frequency(RF) magnetron sputtering.X-ray diffraction(XRD) analysis shows that the films are polycrystalline fitting well with hexagonal wurtzite structure and have a preferred orientation of the(002) plane.The transmittance of above 86% as well as the lowest resistivity of 8.43 × 10^-3 Ω·cm was obtained.
基金supported by the National Natural Science Foundation of China (No. 61671017)Key Project of Excellent Youth Talent Support Program in Colleges and Universities of Anhui Province (No. gxyqZD2018004)+1 种基金Provincial Natural Science Foundation of Anhui Higher Education Institution of China (No. KJ2016A787)Anhui Provincial Natural Science Foundation of China (No. 1508085ME72)
文摘This paper reports a piezoelectric nanogenerator(NG) with a thickness of approximately 80 μm for miniaturized self-powered acceleration sensors. To deposit the piezoelectric zinc oxide(ZnO) thin film, a magnetron sputtering machine was used. Polymethyl methacrylate(PMMA) and aluminum-doped zinc oxide(AZO) were used as the insulating layer and the top electrode of the NG, respectively. The experimental results show that the ZnO thin films annealed at 150℃ exhibited the highest crystallinity among the prepared films and an optical band gap of 3.24 eV. The NG fabricated with an AZO/PMMA/ZnO/stainless steel configuration exhibited a higher output voltage than the device with an AZO/ZnO/PMMA/stainless steel configuration. In addition, the annealing temperature affected the open-circuit voltage of the NGs;the output voltage reached 3.81 V when the annealing temperature was 150℃. The open-circuit voltage of the prepared self-powered accelerometer increased linearly with acceleration. In addition, the small NG-based accelerometer, which exhibited excellent fatigue resistance, can be used for acceleration measurements of small and lightweight devices.
基金supported by the National Natural Science Foundation of China(Grant No.11304160)the Natural Science Foundation of Jiangsu Provincial Higher Education Institutions,China(Grant No.13KJB140008)the Foundation of Nanjing University of Posts and Telecommunications,China(Grant No.NY213018)
文摘Propagation characteristics of surface acoustic waves(SAWs) in ZnO films/glass substrates are theoretically investigated by the three-dimensional(3D) finite element method. At first, for(11ˉ20) ZnO films/glass substrates, the simulation results confirm that the Rayleigh waves along the [0001] direction and Love waves along the [1ˉ100] direction are successfully excited in the multilayered structures. Next, the crystal orientations of the ZnO films are rotated, and the influences of ZnO films with different crystal orientations on SAW characterizations, including the phase velocity, electromechanical coupling coefficient, and temperature coefficient of frequency, are investigated. The results show that at appropriate h/λ, Rayleigh wave has a maximum k^2 of 2.4% in(90°, 56.5°, 0°) ZnO film/glass substrate structure; Love wave has a maximum k^2 of 3.81% in(56°, 90°, 0°) ZnO film/glass substrate structure. Meantime, for Rayleigh wave and Love wave devices, zero temperature coefficient of frequency(TCF) can be achieved at appropriate ratio of film thickness to SAW wavelength. These results show that SAW devices with higher k^2 or lower TCF can be fabricated by flexibly selecting the crystal orientations of ZnO films on glass substrates.
基金Project supported by the "863" High Technology Research Program in China (Grant No 2001AA311120), the National Natural Science Foundation of China (Grant No 60278031), the Innovation Project of Chinese Academy of Sciences, the Jilin Province Science and Technology Development Program Project of China (Grant No 20040564) and the Young Innovation Function of the Changchun Institute of 0ptics, Fine Mechanics and Physics, Chinese Academy of Sciences (Grant No Q03M23Z).
文摘This paper reports the induced growth of high quality ZnO thin film by crystallized amorphous ZnO. Firstly amorphous ZnO was prepared by solid-state pyrolytic reaction, then by taking crystallized amorphous ZnO as seeds (buffer layer), ZnO thin films have been grown in diethyene glycol solution of zinc acetate at 80 ℃. X-ray Diffraction curve indicates that the films were preferentially oriented [001] out-of-plane direction of the ZnO. Atomic force microscopy and scanning electron microscopy were used to evaluate the surface morphology of the ZnO thin film. Photoluminescence spectrum exhibits a strong ultraviolet emission while the visible emission is very weak. The results indicate that high quality ZnO thin film was obtained.
基金This work was financially supported by the Natural Science Foundation of Tianjin (No. 33802311)
文摘The effect of different annealing temperatures on the structure, morphology,and optical properties of ZnO thin films prepared by the chelating sol-gel method was investigated.Zinc-oxide thin films were coated on quartz glass substrates by dip coating. Zinc nitrate, absoluteethanol, and citric acid were used as precursor, solvent, and chelating agent, respectively. Theresults show that ZnO films derived from zinc-citrate have lower crystallization temperature (below400℃), and that the crystal structure is wurtzite. The films, treated over 500℃, consist ofnano-particles and show to be porous at 600℃. The particle size of the film increases with theincrease of the annealing temperature. The largest particle size is 60 nm at 600℃. The opticaltransmittances related to the annealing temperatures become 90% higher in the visible range. Thefilm shows a starting absorption at 380 nm, and the optical band-gap of the thin film (fired at500℃) is 3.25 eV and close to the intrinsic band-gap of ZnO (3.2 eV).
基金Financially supported by the Knowledge Innovation Program of Chinese Academy of Sciences, NNSFC (20831004 and 20771101)CAS Directional Program (No. KJCXZ-YW-M05)a funding from FJIRSM (SZD08002-3)
文摘Zn1-xMgxO (x = 0, 0.18) thin films were fabricated on the copper substrates by radiofrequency magnetron sputtering using the high pure argon as a sputtering gas. The Zn1-xMgxO films were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and galvanostatic tests. The electrochemical test showed an improved electrochemical performance of Zn0.82EMg0.18O thin film as an anode material for lithium ion batteries.
基金Project supported by the Innovation Foundation of Beijing University of Aeronautics and Astronautics for PhD Graduates, China (Grant No. 292122)the Equipment Research Foundation of China (Grant No. 373974)
文摘ZnO thin films co-doped with A1 and Sb with different concentrations and a fixed molar ratio of AlCl3 to SbCl3 at 1:2, are prepared by a sol-gel spin-coating method on glass annealed at 550 ℃ for 2 h in air. The x-ray diffraction results confirm that the ZnO thin films co-doped with Al distortion, and the biaxial stresses are 1.03× 10^8. 3.26× 10^8 and Sb are of wurtzite hexagonal ZnO with a very small 5.23 × 10^8, and 6.97× 10^8 Pa, corresponding to those of the ZnO thin films co-doped with Al and Sb in concentrations of 1.5, 3.0, 4.5, 6.0 at% respectively. The optical properties reveal that the ZnO thin films co-doped with Al and Sb have obviously enhanced transmittance in the visible region. The electrical properties show that ZnO thin film co-doped with Al and Sb in a concentration of 1.5 at% has a lowest resistivity of 2.5 Ω·cm.
基金Funded by Key Project of Natural Science Foundation of Hubei Province(No.2008CDA025)
文摘Aluminium doped ZnO thin films(ZnO︰Al) were deposited on transparent polymer substrates at room temperature by rf magnetron sputtering method from a ZnO target with Al2O3 of 2.0 wt%. Argon gas pressure varied from 0.5 Pa to 2.5 Pa with radio frequency power of 120 W. XRD results showed that all the ZnO︰Al films had a polycrystalline hexagonal structure and a (002) preferred orientation with the c-axis perpendicular to the substrate. The grain sizes of the films were 6.3-14.8 nm.SEM images indicated the ZnO︰Al film with low Argon gas pressure was denser and the deposition rate of the films depended strongly on the Argon gas pressure, increasing firstly and then decreasing with increasing the pressure. The highest deposition rate was 5.2 nm/min at 1 Pa. The optical transmittance of the ZnO︰Al films increased and the blue shift of the absorption edge appeared when the Argon gas pressure increased. The highest transmittance of obtained ZnO︰Al films at 2.5 Pa was about 85% in the visible region. The electrical properties of the films were worsened with the increase of the Argon gas power from 1 Pa to 2.5 Pa. The resistivity of obtained film at 1.0 Pa was 2.79×10-2 Ω·cm.
基金Supported by the National Nature Science Foundation of China(Nos.20071013 and 20301007)
文摘The orientation of the nano-columnar ZnO films grown on sapphire using the technique of metal-organic chemical vapor deposition (MOCVD) exhibits deviation because of the mismatch between the crystal lattices of the films and the sapphire substrate. A high-throughout X-ray diffraction method was employed to determine the crystal orientation of the ZnO films at a time scale of the order of minutes based on the general area detection diffraction system (GADDS). This rapid, effective, and ready method, adapted for characterizing the orientation of the nano-columnar crystals is used to directly explain the results of observation of the X-ray diffraction images, by the measurements of the orientations of the crystal columns of the ZnO films along c-axis and in parallel to ab plane.
基金This work was financially supported by the Key Research Program of National Natural Science Foundation of China (No. 90301002 and No. 90201025)
文摘ZnO thin films were deposited on n-Si (111) at various substrate temperatures by pulsed laser deposition (PLD). X-ray diffraction (XRD), photoluminescence (PL), Fourier transform infrared spectrophotometer (FTIR), and scanning electron microscopy (SEM) were used to analyze the structure, morphology, and optical property of the ZnO thin films. An optimal crystallized ZnO thin film was obtained at the substrate temperature of 600℃. A blue shift was found in PL spectra due to size confinement effect as the grain sizes decreased. The surfaces of the ZnO thin films were more planar and compact as the substrate temperature increased.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50942021 and 11075314)the Fundamental Research Fund for the Central Universities (Grant No. CDJXS10102207)
文摘Indium-doped ZnO thin films are deposited on quartz glass slides by RF magnetron sputtering at ambient temperature. The as-deposited films are annealed at different temperatures from 400℃ to 800 ℃ in air for 1 h. Transmittance spectra are used to determine the optical parameters and the thicknesses of the films before and after annealing using a nonlinear programming method, and the effects of the annealing temperatures on the optical parameters and the thickness are investigated. The optical band gap is determined from the absorption coefficient. The calculated results show that the film thickness and optical parameters both increase first and then decrease with increasing annealing temperature from 400℃ to 800℃. The band gap of the as-deposited ZnO:In thin film is 3.28 eV, and it decreases to 3.17 eV after annealing at 400℃. Then the band gap increases from 3.17 eV to 3.23 eV with increasing annealing temperature from 400℃ to 800℃.