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Meltchakov E, Capitanio B, de Rossi S, Papagiannouli I, Mercère P, Delmotte F. Optimization of Cr/Sc-based multilayer mirrors for water window soft x-rays. OPTICS LETTERS 2024; 49:3420-3423. [PMID: 38875635 DOI: 10.1364/ol.523431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 05/07/2024] [Indexed: 06/16/2024]
Abstract
The development of efficient multilayer mirrors for the water window (a spectral region between absorption edges of carbon and oxygen, from 284 to 543 eV) remains a challenge. As the best candidate, the Cr/Sc multilayer provides maximum theoretical reflectivity of about 60% at near-normal incidence around the Sc L2,3 absorption edge (397 eV). However, the maximum measured peak reflectance published so far just slightly exceeds 20%. We report on a new (to the best of our knowledge) approach to design more efficient Cr/Sc-based multilayer coatings using the process of nitridation of chromium during deposition and adding boron carbide as a third material in the multilayer structure. We discuss our strategy of optimization of the CrN/B4C/Sc multilayer system based on experimental studies. The peak reflectance as high as 32% at 396 eV was measured with this type of coating, which is of main interest for various water window applications such as x-ray microscopy.
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Stendahl S, Ghafoor N, Schwartzkopf M, Zubayer A, Birch J, Eriksson F. Morphology of Buried Interfaces in Ion-Assisted Magnetron Sputter-Deposited 11B 4C-Containing Ni/Ti Multilayer Neutron Optics Investigated by Grazing-Incidence Small-Angle Scattering. ACS APPLIED MATERIALS & INTERFACES 2024; 16:22665-22675. [PMID: 38647102 PMCID: PMC11071035 DOI: 10.1021/acsami.4c01457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 04/05/2024] [Accepted: 04/15/2024] [Indexed: 04/25/2024]
Abstract
Multilayer neutron optics require precise control of interface morphology for optimal performance. In this work, we investigate the effects of different growth conditions on the interface morphology of Ni/Ti-based multilayers, with a focus on incorporating low-neutron-absorbing 11B4C and using different ion assistance schemes. Grazing-incidence small-angle X-ray scattering was used to probe the structural and morphological details of buried interfaces, revealing that the layers become more strongly correlated and the interfaces form mounds with increasing amounts of 11B4C. Applying high flux ion assistance during growth can reduce mound formation but lead to interface mixing, while a high flux modulated ion assistance scheme with an initial buffer layer grown at low ion energy and the top layer at higher ion energy prevents intermixing. The optimal condition was found to be adding 26.0 atom % 11B4C combined with high flux modulated ion assistance. A multilayer with a period of 48.2 Å and 100 periods was grown under these conditions, and coupled fitting to neutron and X-ray reflectivity data revealed an average interface width of only 2.7 Å, a significant improvement over the current state-of-the-art commercial Ni/Ti multilayers. Overall, our study demonstrates that the addition of 11B4C and the use of high flux modulated ion assistance during growth can significantly improve the interface morphology of Ni/Ti multilayers, leading to improved neutron optics performance.
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Affiliation(s)
- Sjoerd Stendahl
- Department
of Physics, Chemistry, and Biology, IFM, Linköping University, SE-581 83 Linköping, Sweden
| | - Naureen Ghafoor
- Department
of Physics, Chemistry, and Biology, IFM, Linköping University, SE-581 83 Linköping, Sweden
| | | | - Anton Zubayer
- Department
of Physics, Chemistry, and Biology, IFM, Linköping University, SE-581 83 Linköping, Sweden
| | - Jens Birch
- Department
of Physics, Chemistry, and Biology, IFM, Linköping University, SE-581 83 Linköping, Sweden
| | - Fredrik Eriksson
- Department
of Physics, Chemistry, and Biology, IFM, Linköping University, SE-581 83 Linköping, Sweden
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Zubayer A, Ghafoor N, Thórarinsdóttir KA, Stendahl S, Glavic A, Stahn J, Nagy G, Greczynski G, Schwartzkopf M, Le Febvrier A, Eklund P, Birch J, Magnus F, Eriksson F. Reflective, polarizing, and magnetically soft amorphous neutron optics with 11B-enriched B 4C. SCIENCE ADVANCES 2024; 10:eadl0402. [PMID: 38354253 PMCID: PMC10866559 DOI: 10.1126/sciadv.adl0402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 01/12/2024] [Indexed: 02/16/2024]
Abstract
The utilization of polarized neutrons is of great importance in scientific disciplines spanning materials science, physics, biology, and chemistry. However, state-of-the-art multilayer polarizing neutron optics have limitations, particularly low specular reflectivity and polarization at higher scattering vectors/angles, and the requirement of high external magnetic fields to saturate the polarizer magnetization. Here, we show that, by incorporating 11B4C into Fe/Si multilayers, amorphization and smooth interfaces can be achieved, yielding higher neutron reflectivity, less diffuse scattering, and higher polarization. Magnetic coercivity is eliminated, and magnetic saturation can be reached at low external fields (>2 militesla). This approach offers prospects for substantial improvement in polarizing neutron optics with nonintrusive positioning of the polarizer, enhanced flux, increased data accuracy, and further polarizing/analyzing methods at neutron scattering facilities.
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Affiliation(s)
- Anton Zubayer
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | - Naureen Ghafoor
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | | | - Sjoerd Stendahl
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | - Artur Glavic
- Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Jochen Stahn
- Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Gyula Nagy
- Department of Physics and Astronomy, Uppsala University, SE-75120, Uppsala, Sweden
| | - Grzegorz Greczynski
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | | | - Arnaud Le Febvrier
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | - Per Eklund
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | - Jens Birch
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | - Fridrik Magnus
- Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik, Iceland
| | - Fredrik Eriksson
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
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Sarkar P, Biswas A, Kumar R, Rai S, Jha SN, Bhattacharyya D. Role of C and B 4C barrier layers in controlling diffusion propagation across the interface of Cr/Sc multilayers. Phys Chem Chem Phys 2023; 25:3072-3082. [PMID: 36620902 DOI: 10.1039/d2cp03785h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The optical performance of low-bilayer-thickness metallic multilayers (ML) can be improved significantly by limiting the intermixing of consecutive layers at the interfaces. Barrier layers are supposed to exhibit a decisive role in controlling diffusion across the interfaces. The element-specific grazing incidence extended X-ray absorption fine structure technique using synchrotron radiation has been used in conjunction with grazing incidence X-ray reflectivity and diffuse X-ray scattering measurements to study the impact of the two most common barrier layers, viz., C and B4C, at the interfaces of Cr/Sc MLs. The diffusion propagation is reduced by both the barrier layers; however, it is found that the improvement is more significant with the B4C barrier layer. It is seen that C forms an intermixed layer with Sc and leads to carbide formation at the interface, which then acts as shielding and prevents further interdiffusion, while B4C hardly penetrates into Sc and stops the overlap between Sc and Cr directly by wetting the corresponding interface. Thus, the above measurements reveal crucial and precise information regarding the elemental diffusion kinetics at the interfaces of Cr/Sc MLs in a non-destructive way, which is very important for technological applications of these MLs as X-ray optical devices.
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Affiliation(s)
- P Sarkar
- Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
| | - A Biswas
- Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
| | - Ravi Kumar
- Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
| | - S Rai
- Synchrotron Utilisation Section, Raja Ramnna Centre for Advanced Technology, Indore 752013, India
| | - S N Jha
- Beamline Development & Applications Section Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - D Bhattacharyya
- Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
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Zhu J, Zhang J, Li H, Tu Y, Chen J, Wang H, Dhesi SS, Cui M, Zhu J, Jonnard P. Improving the soft X-ray reflectivity of Cr/Ti multilayers by co-deposition of B 4C. JOURNAL OF SYNCHROTRON RADIATION 2020; 27:1614-1617. [PMID: 33147186 DOI: 10.1107/s1600577520011741] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 08/27/2020] [Indexed: 06/11/2023]
Abstract
The `water window', covering 2.4-4.4 nm, is an important wavelength range particularly essential to biology research. Cr/Ti multilayers are one of the promising reflecting elements in this region because the near-normal-incidence reflectivity is theoretically as high as 64% at 2.73 nm. However, due to multilayer imperfections, the reported reflectivity is lower than 3% for near-normal incidence. Here, B and C were intentionally incorporated into ultra-thin Cr/Ti soft X-ray multilayers by co-deposition of B4C at the interfaces. The effect on the multilayer structure and composition has been investigated using X-ray reflectometry, X-ray photoelectron spectroscopy, and cross-section electron microscopy. It is shown that B and C are mainly bonded to Ti sites, forming a nonstoichiometric TiBxCy composition, which hinders the interface diffusion, supresses the crystallization of the Cr/Ti multilayer and dramatically improves the interface quality of Cr/TiBxCy multilayers. As a result, the near-normal-incidence reflectivity of soft X-rays increases from 4.48% to 15.75% at a wavelength of 2.73 nm.
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Affiliation(s)
- Jingtao Zhu
- MOE Key Laboratory of Advanced Micro-structured Materials, Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai 200092, People's Republic of China
| | - Jiayi Zhang
- MOE Key Laboratory of Advanced Micro-structured Materials, Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai 200092, People's Republic of China
| | - Haochuan Li
- MOE Key Laboratory of Advanced Micro-structured Materials, Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai 200092, People's Republic of China
| | - Yuchun Tu
- MOE Key Laboratory of Advanced Micro-structured Materials, Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai 200092, People's Republic of China
| | - Jinwen Chen
- MOE Key Laboratory of Advanced Micro-structured Materials, Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai 200092, People's Republic of China
| | - Hongchang Wang
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Sarnjeet S Dhesi
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Mingqi Cui
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academic of Science, Beijing 200092, People's Republic of China
| | - Jie Zhu
- MOE Key Laboratory of Advanced Micro-structured Materials, Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai 200092, People's Republic of China
| | - Philippe Jonnard
- Sorbonne Université, Faculté des Sciences et Ingénierie, UMR CNRS, Laboratoire de Chimie Physique - Matière et Rayonnemment, 4 Place Jussieu, F-75252 Paris Cedex 05, France
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Jiang H, Wang H, Zhu J, Xue C, Zhang J, Tian N, Li A. Thickness-dependent structural characteristics for a sputtering-deposited chromium monolayer and Cr/C and Cr/Sc multilayers. JOURNAL OF SYNCHROTRON RADIATION 2018; 25:785-792. [PMID: 29714189 DOI: 10.1107/s1600577518005143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 03/30/2018] [Indexed: 06/08/2023]
Abstract
The interior structure, morphology and ligand surrounding of a sputtering-deposited chromium monolayer and Cr/C and Cr/Sc multilayers are determined by various hard X-ray techniques in order to reveal the growth characteristics of Cr-based thin films. A Cr monolayer presents a three-stage growth mode with sudden changes occurring at a layer thickness of ∼2 nm and beyond 6 nm. Cr-based multilayers are proven to have denser structures due to interfacial diffusion and layer growth mode. Cr/C and Cr/Sc multilayers have different interfacial widths resulting from asymmetry, degree of crystallinity and thermal stability. Cr/Sc multilayers present similar ligand surroundings to Cr foil, whereas Cr/C multilayers are similar to Cr monolayers. The aim of this study is to help understand the structural evolution regulation versus layer thickness and to improve the deposition technology of Cr-based thin films, in particular for obtaining stable Cr-based multilayers with ultra-short periods.
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Affiliation(s)
- Hui Jiang
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 239 Zhangheng Road, Pudong District, Shanghai 201204, People's Republic of China
| | - Hua Wang
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 239 Zhangheng Road, Pudong District, Shanghai 201204, People's Republic of China
| | - Jingtao Zhu
- MOE Key Laboratory of Advanced Micro-Structured Materials, School of Physics Science and Engineering, Tongji University, Shanghai 200092, People's Republic of China
| | - Chaofan Xue
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 239 Zhangheng Road, Pudong District, Shanghai 201204, People's Republic of China
| | - Jiayi Zhang
- MOE Key Laboratory of Advanced Micro-Structured Materials, School of Physics Science and Engineering, Tongji University, Shanghai 200092, People's Republic of China
| | - Naxi Tian
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 239 Zhangheng Road, Pudong District, Shanghai 201204, People's Republic of China
| | - Aiguo Li
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 239 Zhangheng Road, Pudong District, Shanghai 201204, People's Republic of China
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