Applications of ZnO nanomaterials in optoelectronics are still limited due to their insufficient photoluminescence efficiency. In order to optimize the photoluminescence properties of ZnO nanorods, the UV emission of ...Applications of ZnO nanomaterials in optoelectronics are still limited due to their insufficient photoluminescence efficiency. In order to optimize the photoluminescence properties of ZnO nanorods, the UV emission of vertically aligned ZnO nanorods grown on a Si substrate, in correlation with Ga＋ ion irradiation at different ion energies （0.5 keV-16 keV）, was investigated in the present study. We found that the UV intensity increased rapidly with increasing Ga＋ ion energy, up to its maximum around 2 keV, at which point the intensity was approximately 50 times higher than that produced by as-grown ZnO nanorods. The gentle bombardment of low-energy Ga＋ ions removes defects from ZnO nanorod surfaces. The Ga＋ ions, on the other hand, implant into the nanorods, resulting in compressive strain. It is believed that the perfect arrangement of the crystal lattice upon removal of surface defects and the introduction of compressive strain are two factors that contribute to the significant enhancement of UV light generation.展开更多
Wurzite ZnS:Mn nanorods are synthesized via a solvothermal method by using ethylenediamine and water as mixed solvent.The diameters of the nanorods increase and the lengths decrease with the Mn concentration.High reso...Wurzite ZnS:Mn nanorods are synthesized via a solvothermal method by using ethylenediamine and water as mixed solvent.The diameters of the nanorods increase and the lengths decrease with the Mn concentration.High resolution transmission electron microscopic images illustrate that a few cubic ZnS:Mn nanoparticles arise along with hexagonal nanorods on high Mn concentration.The samples set off yellow-orange emission at 590 nm,characteristic of 4 T→ 6 A 1 transition of Mn 2+ at T d symmetry in ZnS.Electron spin resonance spectrum of the nanorods shows that high Mn concentrations produce a broad envelope,whereas six-line hyperfine appears for lower Mn concentrations.These results together with the magnetization curves indicate that all the ZnS:Mn samples are paramagnetic even down to 4 K,which suggests that the ZnS:Mn is not suitable for dilute magnetic semiconductor.展开更多
ZnO nanorods prepared by a solution-phase method are annealed at different temperatures in oxygen ambient.The luminescence properties of the samples are investigated.In the same excitation condition,the photoluminesce...ZnO nanorods prepared by a solution-phase method are annealed at different temperatures in oxygen ambient.The luminescence properties of the samples are investigated.In the same excitation condition,the photoluminescence(PL) spectra of all samples show an ultraviolet(UV) emission and a broad strong visible emission band.The asymmetric visible emis-sion band of annealed samples has a red-shift as the annealing temperature increasing from 200 ℃ to 600 ℃ and it can be deconvoluted into two subband emissions centered at 535 nm(green emission) and 611 nm(orange-red emission) by Gaussian-fitting analysis.Analyses of PL excitation(PLE) spectra and PL spectra at different excitation wavelengths reveal that the green emission and the orange-red emission have a uniform initial state,which can be attributed to the electron transition from Zn interstitial(Zni) to oxygen vacancy(Vo) and oxygen interstitial(Oi),respectively.展开更多
Hybrid structures composed of layered materials have received much attention due to their exceptional tunable optical, electronic and catalytic properties. Here, we describe a hydrothermal strategy for coupling vertic...Hybrid structures composed of layered materials have received much attention due to their exceptional tunable optical, electronic and catalytic properties. Here, we describe a hydrothermal strategy for coupling vertical ZnO nanorods on MoS2 monolayers without a catalyst. These vapor-solid-grown MoS2 monolayers aid in growing vertical ZnO nanorods via epitaxy. Enhanced Raman and photoluminescence emissions were observed from the MoS2 monolayers under the ZnO nanorods in these coupled structures, which was attributed to the light antenna effect of the ZnO nanorods. These hybrid and incorporation protocols for layered materials will provide new perspectives and opportunities for promoting the construction of heterojunctions with adjustable layered structures leading to fascinating fundamental phenomena and advanced devices.展开更多
基金This research was support by SUG （Start-up funding in NTU）, Tier i （AcRF grant MOE Singapore M401992）, Tier 2 （AcRF grant MOE Singapore M4020159） and the Chinese Natural Science Foundation （Grant 51271031, 60906053, 62174118 and 51308050309）.
文摘Applications of ZnO nanomaterials in optoelectronics are still limited due to their insufficient photoluminescence efficiency. In order to optimize the photoluminescence properties of ZnO nanorods, the UV emission of vertically aligned ZnO nanorods grown on a Si substrate, in correlation with Ga＋ ion irradiation at different ion energies （0.5 keV-16 keV）, was investigated in the present study. We found that the UV intensity increased rapidly with increasing Ga＋ ion energy, up to its maximum around 2 keV, at which point the intensity was approximately 50 times higher than that produced by as-grown ZnO nanorods. The gentle bombardment of low-energy Ga＋ ions removes defects from ZnO nanorod surfaces. The Ga＋ ions, on the other hand, implant into the nanorods, resulting in compressive strain. It is believed that the perfect arrangement of the crystal lattice upon removal of surface defects and the introduction of compressive strain are two factors that contribute to the significant enhancement of UV light generation.
基金supported by the National Natural Science Foundation of China (Grant No.50721091)
文摘Wurzite ZnS:Mn nanorods are synthesized via a solvothermal method by using ethylenediamine and water as mixed solvent.The diameters of the nanorods increase and the lengths decrease with the Mn concentration.High resolution transmission electron microscopic images illustrate that a few cubic ZnS:Mn nanoparticles arise along with hexagonal nanorods on high Mn concentration.The samples set off yellow-orange emission at 590 nm,characteristic of 4 T→ 6 A 1 transition of Mn 2+ at T d symmetry in ZnS.Electron spin resonance spectrum of the nanorods shows that high Mn concentrations produce a broad envelope,whereas six-line hyperfine appears for lower Mn concentrations.These results together with the magnetization curves indicate that all the ZnS:Mn samples are paramagnetic even down to 4 K,which suggests that the ZnS:Mn is not suitable for dilute magnetic semiconductor.
基金supported by the National Natural Science Foundation of China(Nos.60877029,10904109,60977035 and 60907021)the Natural Science Foundation of Tianjin(Nos.09JCYBJC01400 and 10SYSYJC28100)+1 种基金the Key Subject for Materials Physics and Chemistry of Tianjinthe Open Foundation of Key Laboratory of Luminescence and Optical Information of Ministry of Education(Nos.2010LOI02 and 2010LOI11)
文摘ZnO nanorods prepared by a solution-phase method are annealed at different temperatures in oxygen ambient.The luminescence properties of the samples are investigated.In the same excitation condition,the photoluminescence(PL) spectra of all samples show an ultraviolet(UV) emission and a broad strong visible emission band.The asymmetric visible emis-sion band of annealed samples has a red-shift as the annealing temperature increasing from 200 ℃ to 600 ℃ and it can be deconvoluted into two subband emissions centered at 535 nm(green emission) and 611 nm(orange-red emission) by Gaussian-fitting analysis.Analyses of PL excitation(PLE) spectra and PL spectra at different excitation wavelengths reveal that the green emission and the orange-red emission have a uniform initial state,which can be attributed to the electron transition from Zn interstitial(Zni) to oxygen vacancy(Vo) and oxygen interstitial(Oi),respectively.
基金This work was funded by the National Basic Research Program of China （Nos. 2012CB934301 and 2011CBA00905）, the National Natural Science Foundation of China （Nos. 61376016, 61290304 and 61275114） and CAS （No. KSZD-EW-Z-018）. The authors thank Y. L. Jing, X. H. Zhou and T. X. Li for helpful discussions and technical support.
文摘Hybrid structures composed of layered materials have received much attention due to their exceptional tunable optical, electronic and catalytic properties. Here, we describe a hydrothermal strategy for coupling vertical ZnO nanorods on MoS2 monolayers without a catalyst. These vapor-solid-grown MoS2 monolayers aid in growing vertical ZnO nanorods via epitaxy. Enhanced Raman and photoluminescence emissions were observed from the MoS2 monolayers under the ZnO nanorods in these coupled structures, which was attributed to the light antenna effect of the ZnO nanorods. These hybrid and incorporation protocols for layered materials will provide new perspectives and opportunities for promoting the construction of heterojunctions with adjustable layered structures leading to fascinating fundamental phenomena and advanced devices.
