This paper reports that the radio frequency magnetron sputtering is used to fabricate ZnO and Mn-doped ZnO thin films on glass substrates at 500 ℃. The Mn-doped ZnO thin films present wurtzite structure of ZnO and ha...This paper reports that the radio frequency magnetron sputtering is used to fabricate ZnO and Mn-doped ZnO thin films on glass substrates at 500 ℃. The Mn-doped ZnO thin films present wurtzite structure of ZnO and have a smoother surface, better conductivity but no ferromagnetism. The x-ray photoelectron spectroscopy results show that the binding energy of Mn2p3/2 increases with increasing Mn content slightly, and the state of Mn in the Mn-doped ZnO thin films is divalent. The chemisorbed oxygen in the Mn-doped ZnO thin films increases with increasing Mn doping concentration. The photoluminescence spectra of ZnO and Mmdoped ZnO thin films have a similar ultraviolet emission. The yellow green emissions of 4 wt.% and 10 wt.% Mn-doped thin films are quenched, whereas the yellow green emission occurs because of abundant oxygen vacancies in the Mn-doped ZnO thin films after 20 wt.% Mn doping. Compared with pure ZnO thin film, the bandgap of the Mn-doped ZnO thin films increases with increasing Mn content.展开更多
This paper reports that a large amount of Mn-doped ZnO nanorods have been synthesized through thermal evaporation. The morphologies and properties are studied with x-ray diffraction, a scanning electron microscope, tr...This paper reports that a large amount of Mn-doped ZnO nanorods have been synthesized through thermal evaporation. The morphologies and properties are studied with x-ray diffraction, a scanning electron microscope, transmission electron microscope and Raman spectroscope. The results indicate that the manganese atoms occupy the zinc vacancies in the wurtzite lattice of ZnO without forming secondary phases. The exact manganese content has been studied by the x-ray fluorescence spectrum. Meanwhile, the magnetic moment versus temperature result proves that the as-prepared Mn-doped ZnO nanorods show ferromagnetic properties at temperatures as high as 400~K. These studies provide a good understanding of the origin of magnetic properties in diluted magnetic semiconductors.展开更多
A series of Mn-doped ZnO films have been prepared in different sputtering plasmas by using the inductively coupled plasma enhanced physical vapour deposition. The films show paramagnetic behaviour when they are deposi...A series of Mn-doped ZnO films have been prepared in different sputtering plasmas by using the inductively coupled plasma enhanced physical vapour deposition. The films show paramagnetic behaviour when they are deposited in an argon plasma. The Hall measurement indicates that ferromagnetism cannot be realized by increasing the electron concentration. However, the room-temperature ferromagnetism is obtained when the films are deposited in a mixed argon-nitrogen plasma. The first-principles calculations reveal that antiferromagnetic ordering is favoured in the case of the substitution of Mn^2＋ for Zn^2＋ without additional acceptor doping. The substitution of N for O （NO^-） is necessary to induce ferromagnetic couplings in the Zn-Mn-O system. The hybridization between N 2p and Mn 3d provides an empty orbit around the Fermi level. The hopping of Mn 3d electrons through the empty orbit can induce the ferromagnetic coupling. The ferromagnetism in the N-doped Zn-Mn-O system possibly originates from the charge transfer between Mn^2＋ and Mn^3＋ via NO^-, The key factor is the empty orbit provided by substituting N for O, rather than the conductivity type or the carrier concentration.展开更多
In this paper we investigated the optical properties of ZnO and Mn doped ZnO nanocrystals that were fabricated by a vapor phase transport growth process, using zinc acetate dihydrate with or without Mn in a constant O...In this paper we investigated the optical properties of ZnO and Mn doped ZnO nanocrystals that were fabricated by a vapor phase transport growth process, using zinc acetate dihydrate with or without Mn in a constant O2/Ar mixture gas flowing through the furnace at 400600℃, respectively. The as grown ZnO nanocrystals are homogeneous with a mean size of 19 nm observed by scanning electron microscope（SEM）. The optical characteristics were analyzed by absorption spectra and photoluminescence（PL） spectra at room-temperature. For ZnO nanocrystals, a strong and predominant UV emission peaked at 377 nm was found in the PL spectra. For Mn doped ZnO nanocrystals, in addition to the strong UV emission, a strong blue emission peaked at 435 nm was observed as well. By doping Mn ions, the major UV emission shifts from 377 nm to 408 nm, showing that Mn ions were not only incorporated into ZnO Ncs, but also introduced an impurity level in the bandgap. Moreover, with the concentration of Mn increasing, the relative intensities of the two emissions change largely, and the photoluminescence mechanism of them is discussed.展开更多
The microstructural, optical, and magnetic properties and room-temperature photoluminescence （PL） ofMn-doped ZnO thin films were studied. The chemical compositions were examined by energy dispersive X-ray spectrosco...The microstructural, optical, and magnetic properties and room-temperature photoluminescence （PL） ofMn-doped ZnO thin films were studied. The chemical compositions were examined by energy dispersive X-ray spectroscopy （EDS） and the charge state of Mn ions in the ZnO：Mn films was characterized by X-ray photoelectronic spectrometry （XPS）. From the X-ray diffraction （XRD） data of the samples, it can be found that Mn doping does not change the orientation of ZnO thin films. All the films prepared have a wurtzite structure and grow mainly along the c-axis orientation. The grain size and the residual stress were calculated from the XRD results. The optical transmittance of the film decreases with the increase of manganese content in ZnO. The room-temperature photoluminescence of the films shows that the in- tensity of near band energy （NBE） emission depends strongly on the Mn content. The hysteresis behavior indicates that the films with the Mn content below 9at% are ferromagnetic at room temperature.展开更多
Mn-doped ZnO diluted magnetic semiconductor nanoparticles are prepared by an ultrasonic assisted sol-gel process.Transmission electron microscopy shows pseudo-hexagonal nanoparticles with an average size of about 24 n...Mn-doped ZnO diluted magnetic semiconductor nanoparticles are prepared by an ultrasonic assisted sol-gel process.Transmission electron microscopy shows pseudo-hexagonal nanoparticles with an average size of about 24 nm.From the analysis of X-ray diffraction,the Mn-doped ZnO nanoparticles are identified to be a wurtzite structure without any impurity phases.The magnetic properties are measured by using superconducting quantum interference device.For the ZnO with 2% Mn doping concentration,a good hysteresis loop indicates fine ferromagnetism with a Curie temperature higher than 350 K.展开更多
The local structure distortion, the spin Hamiltonian （SH） parameters, and the electric fine structure of the ground state for Mn^2＋ （3d^5） ion in ZnO crystals are systematically investigated, where spin-spin （SS...The local structure distortion, the spin Hamiltonian （SH） parameters, and the electric fine structure of the ground state for Mn^2＋ （3d^5） ion in ZnO crystals are systematically investigated, where spin-spin （SS）, spin-other-orbit （SOO） and orbit-orbit （OO） magnetic interactions, besides the well-known spin-orbit （SO） coupling, are taken into account for the first time, by using the complete diagonalization method. The theoretical results of the second-order zerofield splitting （ZFS） parameter D, the fourth-order ZFS parameter （a-F）, the Zeeman g-factors： g// and g⊥, and the energy differences of the ground state： δ1 and δ2 for Mn^2＋ in Mn^2＋： ZnO are in good agreement with experimental measurements when the three O^2- ions below the Mn^2＋ ion rotate by 1.085° away from the [111]-axis. Hence, the local structure distortion effect plays an important role in explaining the spectroscopic properties of Mn^2＋ ions in Mn^2＋： ZnO crystals. It is found for Mn^2＋ ions in Mn^2＋： ZnO crystals that although the SO mechanism is the most important one, the contributions to the SH parameters, made by other four mechanisms, i.e. SS, SOO, OO, and SO-SS-SOO-OO mechanisms, are significant and should not be omitted, especially for calculating ZFS parameter D.展开更多
Microstructure of ZnO:Mn films with various Mn concentration was investigated with XANES and XPS. The experimental results revealed a substitution of Mn in ZnO and also excluded the existence of Mn oxides or metallic ...Microstructure of ZnO:Mn films with various Mn concentration was investigated with XANES and XPS. The experimental results revealed a substitution of Mn in ZnO and also excluded the existence of Mn oxides or metallic manganese clusters. The substitutional Mn presented a divalent state and all the ZnO:Mn films were n-type. Room temperature ferromagnetism monotonously decreases with the decrease of the electron carrier concentration. The observed ferrmagnetism should come from the carrier-mediated exchange.展开更多
Mn-doped ZnO samples,Zn_(1-x)Mn_(x)O(x=0,0.01,0.03 and 0.05;mole fraction),were successfully synthesized by sonochemical method.The undoped and Mn-doped Zn O samples were characterized by X-ray diffraction(XRD),scanni...Mn-doped ZnO samples,Zn_(1-x)Mn_(x)O(x=0,0.01,0.03 and 0.05;mole fraction),were successfully synthesized by sonochemical method.The undoped and Mn-doped Zn O samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and Raman spectroscopy.XRD patterns of all products are identified to hexagonal wurtzite Zn O structure and their three main peaks shift toward lower diffraction angles due to the incorporation of Mn^(2+)into Zn O crystal lattice.The morphologies of Zn_(1-x)Mn_(x)O(x=0,0.01,0.03 and 0.05)were examined by SEM and TEM.The undoped Zn O sample shows large-scale uniform microflowers which are broken into nanorods and nanoparticles by Mn dopant.Their magnetic properties were investigated by a vibrating sample magnetometer at room temperature.The magnetization-applied field behavior of undoped Zn O defines its weak ferromagnetic behavior.The 3 mol%Mn-doped Zn O shows the highest saturation magnetization of 51.73910^(-3)m A·m^(2)·g^(-1),and the 5 mol%Mn-doped Zn O has suppressed ferromagnetic property due to the formation of Mn clusters inside.展开更多
The first-principles density functional calculation is used to investigate the electronic structures and magnetic properties of Mn-doped and N-co-doped ZnO nanofilms.The band structure calculation shows that the band ...The first-principles density functional calculation is used to investigate the electronic structures and magnetic properties of Mn-doped and N-co-doped ZnO nanofilms.The band structure calculation shows that the band gaps of ZnO films with 2,4,and 6 layers are larger than the band gap of the bulk with wurtzite structure and decrease with the increase of film thickness.However,the four-layer ZnO nanofilms exhibit ferromagnetic phases for Mn concentrations less than 24% and 12% for Mn-doping performed in the whole layers and two layers of the film respectively,while they exhibit spin glass phases for higher Mn concentrations.It is also found,on the one hand,that the spin glass phase turns into the ferromagnetic one,with the substitution of nitrogen atoms for oxygen atoms,for nitrogen concentrations higher than 16% and 5% for Mn-doping performed in the whole layers and two layers of the film respectively.On the other hand,the spin-glass state is more stable for ZnO bulk containing 5% of Mn impurities,while the ferromagnetic phase is stable by introducing the p-type carriers into the bulk system.Moreover,it is shown that using the effective field theory for ferromagnetic system,the Curie temperature is close to the room temperature for the undamped Ruderman-Kittel-Kasuya-Yoshida（RKKY） interaction.展开更多
Porous silicon pillar array（PSPA） samples which are ideal substantial materials with dominant electronic and luminescence properties were prepared by surface etching method. ZnO nanorods with or without Mn doping gr...Porous silicon pillar array（PSPA） samples which are ideal substantial materials with dominant electronic and luminescence properties were prepared by surface etching method. ZnO nanorods with or without Mn doping grown uniformly and aligned onto PSPA regardless of lattice matching show various photoluminescence（PL）properties. The doped Mn ions in ZnO nanorods were directly observed by X-ray photoelectron spectroscopy（XPS）,and ZnO structures were detected by X-ray diffraction（XRD）. As the doping concentration increases,XRD peaks of ZnO nanorods shift to low angle. The influences of doping Mn ions on luminescence properties of ZnO nanorods were investigated. Except for the ultraviolet（UV） PL band, the broad PL band is observed at visible region. The band could be divided into three separate bands（orange, green and red） by Lorentzian deconvolution. The intensity of orange PL band firstly increases then decreases, and then gets the maximum at the doping Mn-to-Zn molar ratio of 2.0：100.0 which is the most effective doping concentration. The green PL band is attributed to zinc vacancy of ZnO, the orange PL band to Mn ions recombination of itself, and the red PL band to oxygen vacancy of ZnO, respectively. As the Mn-doped ZnO nanorods could emit yellow green luminescence excited by UV radiation, and doped Mn ions could improve the color rendering index of the luminescence, the nanorods could be used as promising white-light emitters in the future.展开更多
With the purpose of investigating the origin of ferromagnetism(FM), Mn-doped Zn O thin films had been fabricated by radio frequency(rf) magnetron sputtering and subsequent anneal process. The characterization of the M...With the purpose of investigating the origin of ferromagnetism(FM), Mn-doped Zn O thin films had been fabricated by radio frequency(rf) magnetron sputtering and subsequent anneal process. The characterization of the Mn-doped Zn O thin films was conducted by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), and superconducting quantum interference device(SQUID). With increasing the anneal temperature from 300°C to 700°C for 3 min, the influence on magnetism of the Mndoped ZnO thin films is slight. While extending the anneal time from 3 to 50 min at 300°C, the influence on magnetism is obvious and the Mn-doped ZnO thin films with 30 min clearly demonstrate FM. Compared with the effect of oxygen vacancy and substitutional Mn2+on the ferromagnetic behavior, OVplays the main role in inducing FM of the Mn-doped ZnO thin films with good crystal structure.展开更多
基金Project supported by the State Key Development Program for Basic Research of China (Grant No 2004CB619302)
文摘This paper reports that the radio frequency magnetron sputtering is used to fabricate ZnO and Mn-doped ZnO thin films on glass substrates at 500 ℃. The Mn-doped ZnO thin films present wurtzite structure of ZnO and have a smoother surface, better conductivity but no ferromagnetism. The x-ray photoelectron spectroscopy results show that the binding energy of Mn2p3/2 increases with increasing Mn content slightly, and the state of Mn in the Mn-doped ZnO thin films is divalent. The chemisorbed oxygen in the Mn-doped ZnO thin films increases with increasing Mn doping concentration. The photoluminescence spectra of ZnO and Mmdoped ZnO thin films have a similar ultraviolet emission. The yellow green emissions of 4 wt.% and 10 wt.% Mn-doped thin films are quenched, whereas the yellow green emission occurs because of abundant oxygen vacancies in the Mn-doped ZnO thin films after 20 wt.% Mn doping. Compared with pure ZnO thin film, the bandgap of the Mn-doped ZnO thin films increases with increasing Mn content.
基金supported by "973" Program of Ministry of Science and Technology of China (Grant No. 2006CB932402)National Natural Science Foundation of China (Grant Nos. 50702015, 10574034 and 10774032)
文摘This paper reports that a large amount of Mn-doped ZnO nanorods have been synthesized through thermal evaporation. The morphologies and properties are studied with x-ray diffraction, a scanning electron microscope, transmission electron microscope and Raman spectroscope. The results indicate that the manganese atoms occupy the zinc vacancies in the wurtzite lattice of ZnO without forming secondary phases. The exact manganese content has been studied by the x-ray fluorescence spectrum. Meanwhile, the magnetic moment versus temperature result proves that the as-prepared Mn-doped ZnO nanorods show ferromagnetic properties at temperatures as high as 400~K. These studies provide a good understanding of the origin of magnetic properties in diluted magnetic semiconductors.
基金Project supported by the Shanghai Nanotechnology Promotion Center (Grant No 0452nm071)the National Natural Science Foundation of China (Grant Nos 50702071 and 50772122)
文摘A series of Mn-doped ZnO films have been prepared in different sputtering plasmas by using the inductively coupled plasma enhanced physical vapour deposition. The films show paramagnetic behaviour when they are deposited in an argon plasma. The Hall measurement indicates that ferromagnetism cannot be realized by increasing the electron concentration. However, the room-temperature ferromagnetism is obtained when the films are deposited in a mixed argon-nitrogen plasma. The first-principles calculations reveal that antiferromagnetic ordering is favoured in the case of the substitution of Mn^2＋ for Zn^2＋ without additional acceptor doping. The substitution of N for O （NO^-） is necessary to induce ferromagnetic couplings in the Zn-Mn-O system. The hybridization between N 2p and Mn 3d provides an empty orbit around the Fermi level. The hopping of Mn 3d electrons through the empty orbit can induce the ferromagnetic coupling. The ferromagnetism in the N-doped Zn-Mn-O system possibly originates from the charge transfer between Mn^2＋ and Mn^3＋ via NO^-, The key factor is the empty orbit provided by substituting N for O, rather than the conductivity type or the carrier concentration.
基金supported in parts by the National Natural Science Foundation of China(No.60776004,60976071)the Laboratory for Thin Film Microfabrication of the Ministry of Education
文摘In this paper we investigated the optical properties of ZnO and Mn doped ZnO nanocrystals that were fabricated by a vapor phase transport growth process, using zinc acetate dihydrate with or without Mn in a constant O2/Ar mixture gas flowing through the furnace at 400600℃, respectively. The as grown ZnO nanocrystals are homogeneous with a mean size of 19 nm observed by scanning electron microscope（SEM）. The optical characteristics were analyzed by absorption spectra and photoluminescence（PL） spectra at room-temperature. For ZnO nanocrystals, a strong and predominant UV emission peaked at 377 nm was found in the PL spectra. For Mn doped ZnO nanocrystals, in addition to the strong UV emission, a strong blue emission peaked at 435 nm was observed as well. By doping Mn ions, the major UV emission shifts from 377 nm to 408 nm, showing that Mn ions were not only incorporated into ZnO Ncs, but also introduced an impurity level in the bandgap. Moreover, with the concentration of Mn increasing, the relative intensities of the two emissions change largely, and the photoluminescence mechanism of them is discussed.
基金supported by the National Natural Science Foundation of China(Nos.10774013,10974013,60978060,and 10804006)the National Natural Science Foundation of China for Distinguished Young Scholars(No.60825407)the Doctor Science Creative Grants of Beijing Jiaotong University(No.141028522)
文摘The microstructural, optical, and magnetic properties and room-temperature photoluminescence （PL） ofMn-doped ZnO thin films were studied. The chemical compositions were examined by energy dispersive X-ray spectroscopy （EDS） and the charge state of Mn ions in the ZnO：Mn films was characterized by X-ray photoelectronic spectrometry （XPS）. From the X-ray diffraction （XRD） data of the samples, it can be found that Mn doping does not change the orientation of ZnO thin films. All the films prepared have a wurtzite structure and grow mainly along the c-axis orientation. The grain size and the residual stress were calculated from the XRD results. The optical transmittance of the film decreases with the increase of manganese content in ZnO. The room-temperature photoluminescence of the films shows that the in- tensity of near band energy （NBE） emission depends strongly on the Mn content. The hysteresis behavior indicates that the films with the Mn content below 9at% are ferromagnetic at room temperature.
基金Supported bythe Hunan Provincial Natural Science Foundation ofChina (No.05JJ30126) the Scientific Research Fund of HunanProvincial Education Department (No.04B061)+1 种基金the Key Labora-tory of Advanced Materials & Rheological Properties (Xiangtan University) ,Ministry of Education (No.KF0506) ,the Fundof Xiangtan University (05IND10) .
文摘Mn-doped ZnO diluted magnetic semiconductor nanoparticles are prepared by an ultrasonic assisted sol-gel process.Transmission electron microscopy shows pseudo-hexagonal nanoparticles with an average size of about 24 nm.From the analysis of X-ray diffraction,the Mn-doped ZnO nanoparticles are identified to be a wurtzite structure without any impurity phases.The magnetic properties are measured by using superconducting quantum interference device.For the ZnO with 2% Mn doping concentration,a good hysteresis loop indicates fine ferromagnetism with a Curie temperature higher than 350 K.
基金supported by the Science and Technology Foundation of Shaanxi Province,China (Grant No 2006K04-G29)the National Defense Foundation of China (Grant No EP060302)the Key Research Foundation of Baoji University of Arts and Sciences,China (Grant No ZK0842)
文摘The local structure distortion, the spin Hamiltonian （SH） parameters, and the electric fine structure of the ground state for Mn^2＋ （3d^5） ion in ZnO crystals are systematically investigated, where spin-spin （SS）, spin-other-orbit （SOO） and orbit-orbit （OO） magnetic interactions, besides the well-known spin-orbit （SO） coupling, are taken into account for the first time, by using the complete diagonalization method. The theoretical results of the second-order zerofield splitting （ZFS） parameter D, the fourth-order ZFS parameter （a-F）, the Zeeman g-factors： g// and g⊥, and the energy differences of the ground state： δ1 and δ2 for Mn^2＋ in Mn^2＋： ZnO are in good agreement with experimental measurements when the three O^2- ions below the Mn^2＋ ion rotate by 1.085° away from the [111]-axis. Hence, the local structure distortion effect plays an important role in explaining the spectroscopic properties of Mn^2＋ ions in Mn^2＋： ZnO crystals. It is found for Mn^2＋ ions in Mn^2＋： ZnO crystals that although the SO mechanism is the most important one, the contributions to the SH parameters, made by other four mechanisms, i.e. SS, SOO, OO, and SO-SS-SOO-OO mechanisms, are significant and should not be omitted, especially for calculating ZFS parameter D.
文摘Microstructure of ZnO:Mn films with various Mn concentration was investigated with XANES and XPS. The experimental results revealed a substitution of Mn in ZnO and also excluded the existence of Mn oxides or metallic manganese clusters. The substitutional Mn presented a divalent state and all the ZnO:Mn films were n-type. Room temperature ferromagnetism monotonously decreases with the decrease of the electron carrier concentration. The observed ferrmagnetism should come from the carrier-mediated exchange.
基金financially supported by the National Research University(NRU)Project for Chiang Mai UniversityBansomdejchaopraya Rajabhat University(BSRU)Research Fund。
文摘Mn-doped ZnO samples,Zn_(1-x)Mn_(x)O(x=0,0.01,0.03 and 0.05;mole fraction),were successfully synthesized by sonochemical method.The undoped and Mn-doped Zn O samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and Raman spectroscopy.XRD patterns of all products are identified to hexagonal wurtzite Zn O structure and their three main peaks shift toward lower diffraction angles due to the incorporation of Mn^(2+)into Zn O crystal lattice.The morphologies of Zn_(1-x)Mn_(x)O(x=0,0.01,0.03 and 0.05)were examined by SEM and TEM.The undoped Zn O sample shows large-scale uniform microflowers which are broken into nanorods and nanoparticles by Mn dopant.Their magnetic properties were investigated by a vibrating sample magnetometer at room temperature.The magnetization-applied field behavior of undoped Zn O defines its weak ferromagnetic behavior.The 3 mol%Mn-doped Zn O shows the highest saturation magnetization of 51.73910^(-3)m A·m^(2)·g^(-1),and the 5 mol%Mn-doped Zn O has suppressed ferromagnetic property due to the formation of Mn clusters inside.
文摘The first-principles density functional calculation is used to investigate the electronic structures and magnetic properties of Mn-doped and N-co-doped ZnO nanofilms.The band structure calculation shows that the band gaps of ZnO films with 2,4,and 6 layers are larger than the band gap of the bulk with wurtzite structure and decrease with the increase of film thickness.However,the four-layer ZnO nanofilms exhibit ferromagnetic phases for Mn concentrations less than 24% and 12% for Mn-doping performed in the whole layers and two layers of the film respectively,while they exhibit spin glass phases for higher Mn concentrations.It is also found,on the one hand,that the spin glass phase turns into the ferromagnetic one,with the substitution of nitrogen atoms for oxygen atoms,for nitrogen concentrations higher than 16% and 5% for Mn-doping performed in the whole layers and two layers of the film respectively.On the other hand,the spin-glass state is more stable for ZnO bulk containing 5% of Mn impurities,while the ferromagnetic phase is stable by introducing the p-type carriers into the bulk system.Moreover,it is shown that using the effective field theory for ferromagnetic system,the Curie temperature is close to the room temperature for the undamped Ruderman-Kittel-Kasuya-Yoshida（RKKY） interaction.
基金financially supported by the National Natural Science Foundation of China (No.11104008)the Beijing Natural Science Foundation (No.4142040)the Fundamental Research Funds for Central Universities of China (No. 212-105560GK)
文摘Porous silicon pillar array（PSPA） samples which are ideal substantial materials with dominant electronic and luminescence properties were prepared by surface etching method. ZnO nanorods with or without Mn doping grown uniformly and aligned onto PSPA regardless of lattice matching show various photoluminescence（PL）properties. The doped Mn ions in ZnO nanorods were directly observed by X-ray photoelectron spectroscopy（XPS）,and ZnO structures were detected by X-ray diffraction（XRD）. As the doping concentration increases,XRD peaks of ZnO nanorods shift to low angle. The influences of doping Mn ions on luminescence properties of ZnO nanorods were investigated. Except for the ultraviolet（UV） PL band, the broad PL band is observed at visible region. The band could be divided into three separate bands（orange, green and red） by Lorentzian deconvolution. The intensity of orange PL band firstly increases then decreases, and then gets the maximum at the doping Mn-to-Zn molar ratio of 2.0：100.0 which is the most effective doping concentration. The green PL band is attributed to zinc vacancy of ZnO, the orange PL band to Mn ions recombination of itself, and the red PL band to oxygen vacancy of ZnO, respectively. As the Mn-doped ZnO nanorods could emit yellow green luminescence excited by UV radiation, and doped Mn ions could improve the color rendering index of the luminescence, the nanorods could be used as promising white-light emitters in the future.
文摘With the purpose of investigating the origin of ferromagnetism(FM), Mn-doped Zn O thin films had been fabricated by radio frequency(rf) magnetron sputtering and subsequent anneal process. The characterization of the Mn-doped Zn O thin films was conducted by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), and superconducting quantum interference device(SQUID). With increasing the anneal temperature from 300°C to 700°C for 3 min, the influence on magnetism of the Mndoped ZnO thin films is slight. While extending the anneal time from 3 to 50 min at 300°C, the influence on magnetism is obvious and the Mn-doped ZnO thin films with 30 min clearly demonstrate FM. Compared with the effect of oxygen vacancy and substitutional Mn2+on the ferromagnetic behavior, OVplays the main role in inducing FM of the Mn-doped ZnO thin films with good crystal structure.
