X-ray microscopy is an essential imaging method in many scientific fields,which can be extended to three-dimensional(3D)using tomography.Recently,metal halide perovskite(MHP)nanomaterials have become a promising candi...X-ray microscopy is an essential imaging method in many scientific fields,which can be extended to three-dimensional(3D)using tomography.Recently,metal halide perovskite(MHP)nanomaterials have become a promising candidate for X-ray scintillators,due to their high light yield,high spatial resolution,and easy fabrication.Tomography requires many projections and therefore scintillators with excellent stability.This is challenging for MHPs,which often suffer from fast degradation under X-ray irradiation and ambient conditions.Here,we demonstrate that MHP scintillators of CsPbBr3 nanowires(diameter:60 nm,length:5–9μm)grown in anodized aluminum oxide(CsPbBr3 NW/AAO)have sufficient stability for X-ray micro-tomography.A tomogram was taken with a Cu X-ray source over 41 h(dose 4.2 Gyair).During this period the scintillator brightness fluctuated less than 5%,which enabled a successful reconstruction.A long-term study with 2 weeks of continuous X-ray exposure(37.5 Gyair)showed less than 14%fluctuations in brightness and no long-term degradation,despite variations in the ambient relative humidity from 7.4%RH to 34.2%RH.The resolution was stable at(180±20)lp·mm−1,i.e.,about 2.8 micron.This demonstrates that CsPbBr3 NW/AAO scintillators are promising candidates for high resolution X-ray imaging detectors.展开更多
We report a method using in situ etching to decouple the axial from the radial nanowire growth pathway,independent of other growth parameters.Thereby a wide range of growth parameters can be explored to improve the na...We report a method using in situ etching to decouple the axial from the radial nanowire growth pathway,independent of other growth parameters.Thereby a wide range of growth parameters can be explored to improve the nanowire properties without concern of tapering or excess structural defects formed during radial growth.We demonstrate the method using etching by HCl during InP nanowire growth.The improved crystal quality of etched nanowires is indicated by strongly enhanced photoluminescence as compared to reference nanowires obtained without etching.展开更多
Axially heterostructured nanowires are a promising platform for next generation electronic and optoelectronic devices.Reports based on theoretical modeling have predicted more complex strain distributions and increase...Axially heterostructured nanowires are a promising platform for next generation electronic and optoelectronic devices.Reports based on theoretical modeling have predicted more complex strain distributions and increased critical layer thicknesses than in thin films,due to lateral strain relaxation at the surface,but the understanding of the growth and strain distributions in these complex structures is hampered by the lack of high-resolution characterization techniques.Here,we demonstrate strain mapping of an axially segmented GalnP-lnP 190 nm diameter nanowire heterostructure using scanning X-ray diffraction.We systematically investigate the strain distribution and lattice tilt in three different segment lengths from 45 to 170 nm,obtaining strain maps with about 10^-4 relative strain sensitivity.The experiments were performed using the 90 nm diameter nanofocus at the NanoMAX beamline,taking advantage of the high coherent flux from the first diffraction limited storage ring MAX IV.The experimental results are in good agreement with a full simulation of the experiment based on a three-dimensional(3D)finite element model.The largest segments show a complex profile,where the lateral strain relaxation at the surface leads to a dome-shaped strain distribution from the mismatched interfaces,and a change from tensile to compressive strain within a single segment.The lattice tilt maps show a cross-shaped profile with excellent qualitative and quantitative agreement with the simulations.In contrast,the shortest measured InP segment is almost fully adapted to the surrounding GalnP segments.展开更多
基金This project received funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(Grant 801847).
文摘X-ray microscopy is an essential imaging method in many scientific fields,which can be extended to three-dimensional(3D)using tomography.Recently,metal halide perovskite(MHP)nanomaterials have become a promising candidate for X-ray scintillators,due to their high light yield,high spatial resolution,and easy fabrication.Tomography requires many projections and therefore scintillators with excellent stability.This is challenging for MHPs,which often suffer from fast degradation under X-ray irradiation and ambient conditions.Here,we demonstrate that MHP scintillators of CsPbBr3 nanowires(diameter:60 nm,length:5–9μm)grown in anodized aluminum oxide(CsPbBr3 NW/AAO)have sufficient stability for X-ray micro-tomography.A tomogram was taken with a Cu X-ray source over 41 h(dose 4.2 Gyair).During this period the scintillator brightness fluctuated less than 5%,which enabled a successful reconstruction.A long-term study with 2 weeks of continuous X-ray exposure(37.5 Gyair)showed less than 14%fluctuations in brightness and no long-term degradation,despite variations in the ambient relative humidity from 7.4%RH to 34.2%RH.The resolution was stable at(180±20)lp·mm−1,i.e.,about 2.8 micron.This demonstrates that CsPbBr3 NW/AAO scintillators are promising candidates for high resolution X-ray imaging detectors.
基金This work was performed within the Nanometer Structure Consortium at Lund University and supported by the Swedish Energy Agency,the Swedish Research Council,the Swedish Foundation for Strategic Research,and by the EU programs AMON-RA(No.214814)and NODE(No.015783)This report is based on a project which was funded by E.ON AG as part of the E.ON International Research Initiative.Responsibility for the content of this publication lies with the authors.
文摘We report a method using in situ etching to decouple the axial from the radial nanowire growth pathway,independent of other growth parameters.Thereby a wide range of growth parameters can be explored to improve the nanowire properties without concern of tapering or excess structural defects formed during radial growth.We demonstrate the method using etching by HCl during InP nanowire growth.The improved crystal quality of etched nanowires is indicated by strongly enhanced photoluminescence as compared to reference nanowires obtained without etching.
基金Open access funding provided by Lund University.
文摘Axially heterostructured nanowires are a promising platform for next generation electronic and optoelectronic devices.Reports based on theoretical modeling have predicted more complex strain distributions and increased critical layer thicknesses than in thin films,due to lateral strain relaxation at the surface,but the understanding of the growth and strain distributions in these complex structures is hampered by the lack of high-resolution characterization techniques.Here,we demonstrate strain mapping of an axially segmented GalnP-lnP 190 nm diameter nanowire heterostructure using scanning X-ray diffraction.We systematically investigate the strain distribution and lattice tilt in three different segment lengths from 45 to 170 nm,obtaining strain maps with about 10^-4 relative strain sensitivity.The experiments were performed using the 90 nm diameter nanofocus at the NanoMAX beamline,taking advantage of the high coherent flux from the first diffraction limited storage ring MAX IV.The experimental results are in good agreement with a full simulation of the experiment based on a three-dimensional(3D)finite element model.The largest segments show a complex profile,where the lateral strain relaxation at the surface leads to a dome-shaped strain distribution from the mismatched interfaces,and a change from tensile to compressive strain within a single segment.The lattice tilt maps show a cross-shaped profile with excellent qualitative and quantitative agreement with the simulations.In contrast,the shortest measured InP segment is almost fully adapted to the surrounding GalnP segments.
