In this study,the influence of substrate temperature on properties of Al-N co-doped p-type ZnO films is explored.Benefitting from the high ionization rate in high-power impulsed magnetron sputtering,the concentration ...In this study,the influence of substrate temperature on properties of Al-N co-doped p-type ZnO films is explored.Benefitting from the high ionization rate in high-power impulsed magnetron sputtering,the concentration of ionized nitrogen N+and ionized zinc Zn+were increased,which promoted the formation of ZnO films and lowered the necessary substrate temperature.After optimization,a co-doped p-type ZnO thin film with a resistivity lower than 0.35Ωcm and a hole concentration higher than 5.34×10^(18)cm^(-3)is grown at 280°C.X-ray diffraction results confirm that Al-N co-doping does not destruct the ZnO wurtzite structure.X-ray photoelectron spectroscopy demonstrates that the presence of Al promotes the formation of acceptor(No)defects in ZnO films,and ensures the role of Al in stabilizing p-type ZnO.展开更多
A simple and easily operated technique was developed to fabricate GaN films. GaN films possessing hexagonal wurtzite structure were fabricated on Si(111) substrates with ZnO buffer layers through nitriding Ga2O3 films...A simple and easily operated technique was developed to fabricate GaN films. GaN films possessing hexagonal wurtzite structure were fabricated on Si(111) substrates with ZnO buffer layers through nitriding Ga2O3 films in the tube quartz furnace. ZnO buffer layers and Ga3O3 films were deposited on Si substrates in turn by using radio frequency magnetron sputtering system before the nitriding process. The structure and composition of GaN films were studied by X-ray diffraction, selected area electron diffraction and Fourier transform infrared spectrophotometer. The morphologies of GaN films were studied by scanning electron microscopy. The results show that ZnO buffer layer improves the crystalline quality and the surface morphology of the films relative to the films grown directly on silicon substrates. The measurement result of room-temperature photoluminescence spectrum indicates that the photoluminescence peaks locate at 365 nm and 422 nm.展开更多
Pure ZnO thick film, prepared by screen-printing technique, was almost insensitive to NH3. Pure ZnO thick films were surface modified with MnO2 by dipping them into 0.01 M aqueous solution of manganese chloride (MnCl2...Pure ZnO thick film, prepared by screen-printing technique, was almost insensitive to NH3. Pure ZnO thick films were surface modified with MnO2 by dipping them into 0.01 M aqueous solution of manganese chloride (MnCl2) for different intervals of time and fired at 500℃ for 12 h. The grains of MnO2 would disperse around the grains of ZnO base material. The MnO2 modified ZnO films dipped for 30 min were observed to be sensitive and highly selective to NH3 gas at room temperature. An exceptional sensitivity was found to low concentration (50 ppm) of NH3 gas at room temperature and no cross sensitivity was observed even to high concentrations of other hazardous and polluting gases. The effects of surface microstructure and MnO2 concentrations on the sensitivity, selectivity, response and recovery of the sensor in the presence of NH3and other gases were studied and discussed. The better performance could be attributed to an optimum number of surface misfits in terms of MnO2 on the ZnO films.展开更多
P-type nitrogen-doped ZnO films are prepared successfully by in-situ thermal oxidation of Zn3N2 films. The prepared films are characterized by x-ray diffraction, non-Rutherford back.scattering （non-RBS） spectroscopy...P-type nitrogen-doped ZnO films are prepared successfully by in-situ thermal oxidation of Zn3N2 films. The prepared films are characterized by x-ray diffraction, non-Rutherford back.scattering （non-RBS） spectroscopy, x- ray photoelectron spectroscopy, and photoluminescence spectrum. The results show that the Zn3N1 films start to transform to ZnO at 400℃ and the total nitrogen content decreases with the increasing annealing temperature. The p-type fihns are achieved at 500℃ with a low resistivity of 6.33Ω.cm and a high hole concentration of ＋8.82 × 10^17 cm-3, as well as a low level of carbon contamination, indicating that the substitutional nitrogen （No） is an effective acceptor in the ZnO：N film. The photoluminescence spectra show clear UV emissions and also indicate the presence of oxygen vacancy （Vo） defects in the ZnO：N films. The p-type doping mechanism is briefly discussed.展开更多
ZnO thin films were deposited on the substrates of （100） γ-LiAlO2 at 400,550 and 700℃ using pulsed laser deposition （PLD） with the fixed oxygen pressure of 20 Pa, respectively. When the substrate temperature is ...ZnO thin films were deposited on the substrates of （100） γ-LiAlO2 at 400,550 and 700℃ using pulsed laser deposition （PLD） with the fixed oxygen pressure of 20 Pa, respectively. When the substrate temperature is 400℃, the grain size of the film is less than 1μm observed by Leitz microscope and measured by X-ray diffraction （XRD）. As the substrate temperature increases to 550℃, highly-preferred c-orientation and high-quality ZnO film can be attained.While the substrate temperature rises to 700℃, more defects appears on the surface of film and the ZnO films become polycrystalline again possibly because more Li of the substrate diffused into the ZnO film at high substrate temperature. The photoluminescence （PL） spectra of ZnO films at room temperature show the blue emission peaks centered at 430 nm. We suggest that the blue emission corresponds to the electron transition from the level of interstitial Zn to the valence band. Meanwhile, the films grown on γ-LiAl02 （LAO） exhibit green emission centered at 540 nm, which seemed to be ascribed to excess zinc and/or oxygen vacancy in the ZnO films caused by diffusion of Li from the substrates into the films during the deposition.展开更多
Development of metal oxide semiconductors-based methane sensors with good response and low power consumption is one of the major challenges to realize the real-time monitoring of methane leakage.In this work,a self-as...Development of metal oxide semiconductors-based methane sensors with good response and low power consumption is one of the major challenges to realize the real-time monitoring of methane leakage.In this work,a self-assembled mulberry-like ZnO/SnO_(2)hierarchical structure is constructed by a two-step hydrothermal method.The resultant sensor works at room temperature with excellent response of~56.1%to 2000 ppm CH_(4)at 55%relative humidity.It is found that the strain induced at the ZnO/SnO_(2)interface greatly enhances the piezoelectric polarization on the ZnO surface and that the band bending results in the accumulation of chemically adsorbed O_(2)^(-)ions close to the interface,leading to significant improvement in the sensing performance of the methane gas sensor at room temperature.展开更多
目的提高真空保温管道中红外反射层的红外反射性能。方法以四水合醋酸钴和二水合乙酸锌为金属离子源,利用溶胶-凝胶法制备了不同Co掺杂量的ZnO溶胶(Zn1–xCoxO,x=0,0.02,0.04,0.06,0.08,0.10)。进一步采用提拉法在镜面316L不锈钢表面制...目的提高真空保温管道中红外反射层的红外反射性能。方法以四水合醋酸钴和二水合乙酸锌为金属离子源,利用溶胶-凝胶法制备了不同Co掺杂量的ZnO溶胶(Zn1–xCoxO,x=0,0.02,0.04,0.06,0.08,0.10)。进一步采用提拉法在镜面316L不锈钢表面制备薄膜,经450℃退火处理3 h后得到所需样品。利用热重-差示扫描量热法(TG-DSC)表征Zn1–xCoxO凝胶在热处理时发生的干燥、晶化过程。利用X射线衍射仪(XRD)分析表征不同Co掺杂量的薄膜中的物相组成。利用场发射扫描电子显微镜(FE-SEM)观察薄膜表面的微观形貌。利用能谱仪分析(EDS)热处理后薄膜表面的元素分布情况。利用UV-Vis-NIR分光光度计测试涂层的红外反射性能。结果所得的Zn1–xCoxO溶胶在基体表面铺展良好,经热处理后晶粒分布均匀,表面致密无明显缺陷;涂敷Zn1–xCoxO薄膜后,样品红外反射性能得到明显改善,由纯基体的0.6355提升至最佳值0.8131(其中,x=0.06)。同时,XRD结果表明掺杂并未导致样品物相的改变,薄膜材料仍然保持稳定的六角纤锌矿结构,但随着Co掺杂量的提高,样品在(101)晶面发生择优取向。经28 d 400℃有氧热处理后,试样仍能保持0.8018的较高反射率。结论通过在红外反射层表面涂敷Zn1–xCoxO薄膜,不但可有效提高其红外反射率,还可对内部金属基体起到良好的保护作用,从而提高热力管道的隔热性能和使用寿命。展开更多
基金supported by National Natural Science Foundation of China(Nos.11875090,12075032,11775028,11875088,11974048)Beijing Municipal National Science Foundation(Nos.1192008,KZ202010015022)BIGC(Nos.Ea201901,Ee202001)。
文摘In this study,the influence of substrate temperature on properties of Al-N co-doped p-type ZnO films is explored.Benefitting from the high ionization rate in high-power impulsed magnetron sputtering,the concentration of ionized nitrogen N+and ionized zinc Zn+were increased,which promoted the formation of ZnO films and lowered the necessary substrate temperature.After optimization,a co-doped p-type ZnO thin film with a resistivity lower than 0.35Ωcm and a hole concentration higher than 5.34×10^(18)cm^(-3)is grown at 280°C.X-ray diffraction results confirm that Al-N co-doping does not destruct the ZnO wurtzite structure.X-ray photoelectron spectroscopy demonstrates that the presence of Al promotes the formation of acceptor(No)defects in ZnO films,and ensures the role of Al in stabilizing p-type ZnO.
基金Projects(90301002 90201025) supported by the National Natural Science Foundation of China
文摘A simple and easily operated technique was developed to fabricate GaN films. GaN films possessing hexagonal wurtzite structure were fabricated on Si(111) substrates with ZnO buffer layers through nitriding Ga2O3 films in the tube quartz furnace. ZnO buffer layers and Ga3O3 films were deposited on Si substrates in turn by using radio frequency magnetron sputtering system before the nitriding process. The structure and composition of GaN films were studied by X-ray diffraction, selected area electron diffraction and Fourier transform infrared spectrophotometer. The morphologies of GaN films were studied by scanning electron microscopy. The results show that ZnO buffer layer improves the crystalline quality and the surface morphology of the films relative to the films grown directly on silicon substrates. The measurement result of room-temperature photoluminescence spectrum indicates that the photoluminescence peaks locate at 365 nm and 422 nm.
文摘Pure ZnO thick film, prepared by screen-printing technique, was almost insensitive to NH3. Pure ZnO thick films were surface modified with MnO2 by dipping them into 0.01 M aqueous solution of manganese chloride (MnCl2) for different intervals of time and fired at 500℃ for 12 h. The grains of MnO2 would disperse around the grains of ZnO base material. The MnO2 modified ZnO films dipped for 30 min were observed to be sensitive and highly selective to NH3 gas at room temperature. An exceptional sensitivity was found to low concentration (50 ppm) of NH3 gas at room temperature and no cross sensitivity was observed even to high concentrations of other hazardous and polluting gases. The effects of surface microstructure and MnO2 concentrations on the sensitivity, selectivity, response and recovery of the sensor in the presence of NH3and other gases were studied and discussed. The better performance could be attributed to an optimum number of surface misfits in terms of MnO2 on the ZnO films.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10775033 and 11075038
文摘P-type nitrogen-doped ZnO films are prepared successfully by in-situ thermal oxidation of Zn3N2 films. The prepared films are characterized by x-ray diffraction, non-Rutherford back.scattering （non-RBS） spectroscopy, x- ray photoelectron spectroscopy, and photoluminescence spectrum. The results show that the Zn3N1 films start to transform to ZnO at 400℃ and the total nitrogen content decreases with the increasing annealing temperature. The p-type fihns are achieved at 500℃ with a low resistivity of 6.33Ω.cm and a high hole concentration of ＋8.82 × 10^17 cm-3, as well as a low level of carbon contamination, indicating that the substitutional nitrogen （No） is an effective acceptor in the ZnO：N film. The photoluminescence spectra show clear UV emissions and also indicate the presence of oxygen vacancy （Vo） defects in the ZnO：N films. The p-type doping mechanism is briefly discussed.
文摘ZnO thin films were deposited on the substrates of （100） γ-LiAlO2 at 400,550 and 700℃ using pulsed laser deposition （PLD） with the fixed oxygen pressure of 20 Pa, respectively. When the substrate temperature is 400℃, the grain size of the film is less than 1μm observed by Leitz microscope and measured by X-ray diffraction （XRD）. As the substrate temperature increases to 550℃, highly-preferred c-orientation and high-quality ZnO film can be attained.While the substrate temperature rises to 700℃, more defects appears on the surface of film and the ZnO films become polycrystalline again possibly because more Li of the substrate diffused into the ZnO film at high substrate temperature. The photoluminescence （PL） spectra of ZnO films at room temperature show the blue emission peaks centered at 430 nm. We suggest that the blue emission corresponds to the electron transition from the level of interstitial Zn to the valence band. Meanwhile, the films grown on γ-LiAl02 （LAO） exhibit green emission centered at 540 nm, which seemed to be ascribed to excess zinc and/or oxygen vacancy in the ZnO films caused by diffusion of Li from the substrates into the films during the deposition.
基金financially supported by the National Natural Science Foundation of China(No.12174092,21902046,U21A20500)Overseas Expertise Introduction Center for Discipline Innovation(D18025)+1 种基金Hubei Provincial Department of Science and Technology(No.2019CFA079)Wuhan Science and Technology Bureau(2020010601012163)
文摘Development of metal oxide semiconductors-based methane sensors with good response and low power consumption is one of the major challenges to realize the real-time monitoring of methane leakage.In this work,a self-assembled mulberry-like ZnO/SnO_(2)hierarchical structure is constructed by a two-step hydrothermal method.The resultant sensor works at room temperature with excellent response of~56.1%to 2000 ppm CH_(4)at 55%relative humidity.It is found that the strain induced at the ZnO/SnO_(2)interface greatly enhances the piezoelectric polarization on the ZnO surface and that the band bending results in the accumulation of chemically adsorbed O_(2)^(-)ions close to the interface,leading to significant improvement in the sensing performance of the methane gas sensor at room temperature.
文摘目的提高真空保温管道中红外反射层的红外反射性能。方法以四水合醋酸钴和二水合乙酸锌为金属离子源,利用溶胶-凝胶法制备了不同Co掺杂量的ZnO溶胶(Zn1–xCoxO,x=0,0.02,0.04,0.06,0.08,0.10)。进一步采用提拉法在镜面316L不锈钢表面制备薄膜,经450℃退火处理3 h后得到所需样品。利用热重-差示扫描量热法(TG-DSC)表征Zn1–xCoxO凝胶在热处理时发生的干燥、晶化过程。利用X射线衍射仪(XRD)分析表征不同Co掺杂量的薄膜中的物相组成。利用场发射扫描电子显微镜(FE-SEM)观察薄膜表面的微观形貌。利用能谱仪分析(EDS)热处理后薄膜表面的元素分布情况。利用UV-Vis-NIR分光光度计测试涂层的红外反射性能。结果所得的Zn1–xCoxO溶胶在基体表面铺展良好,经热处理后晶粒分布均匀,表面致密无明显缺陷;涂敷Zn1–xCoxO薄膜后,样品红外反射性能得到明显改善,由纯基体的0.6355提升至最佳值0.8131(其中,x=0.06)。同时,XRD结果表明掺杂并未导致样品物相的改变,薄膜材料仍然保持稳定的六角纤锌矿结构,但随着Co掺杂量的提高,样品在(101)晶面发生择优取向。经28 d 400℃有氧热处理后,试样仍能保持0.8018的较高反射率。结论通过在红外反射层表面涂敷Zn1–xCoxO薄膜,不但可有效提高其红外反射率,还可对内部金属基体起到良好的保护作用,从而提高热力管道的隔热性能和使用寿命。
