1
|
Hatzoglou C, Da Costa G, Wells P, Ren X, Geiser BP, Larson DJ, Demoulin R, Hunnestad K, Talbot E, Mazumder B, Meier D, Vurpillot F. Introducing a Dynamic Reconstruction Methodology for Multilayered Structures in Atom Probe Tomography. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1124-1136. [PMID: 37749700 DOI: 10.1093/micmic/ozad054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 03/08/2023] [Accepted: 04/18/2023] [Indexed: 09/27/2023]
Abstract
Atom probe tomography (APT) is a powerful three-dimensional nanoanalyzing microscopy technique considered key in modern materials science. However, progress in the spatial reconstruction of APT data has been rather limited since the first implementation of the protocol proposed by Bas et al. in 1995. This paper proposes a simple semianalytical approach to reconstruct multilayered structures, i.e., two or more different compounds stacked perpendicular to the analysis direction. Using a field evaporation model, the general dynamic evolution of parameters involved in the reconstruction of this type of structure is estimated. Some experimental reconstructions of different structures through the implementation of this method that dynamically accommodates variations in the tomographic reconstruction parameters are presented. It is shown both experimentally and theoretically that the depth accuracy of reconstructed APT images is improved using this method. The method requires few parameters in order to be easily usable and substantially improves atom probe tomographic reconstructions of multilayered structures.
Collapse
Affiliation(s)
- Constantinos Hatzoglou
- INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux UMR 6634, Univ Rouen Normandie, INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux UMR 6634, Rouen F-76000, France
- Department of Materials Science and Engineering, NTNU, Norwegian University of Science and Technology, Trondheim 7491, Norway
| | - Gérald Da Costa
- INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux UMR 6634, Univ Rouen Normandie, INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux UMR 6634, Rouen F-76000, France
| | | | | | - Brian P Geiser
- CAMECA Instruments Inc., 5470 Nobel Dr., Madison, WI 53711, USA
| | - David J Larson
- CAMECA Instruments Inc., 5470 Nobel Dr., Madison, WI 53711, USA
| | - Remi Demoulin
- INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux UMR 6634, Univ Rouen Normandie, INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux UMR 6634, Rouen F-76000, France
| | - Kasper Hunnestad
- Department of Materials Science and Engineering, NTNU, Norwegian University of Science and Technology, Trondheim 7491, Norway
| | - Etienne Talbot
- INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux UMR 6634, Univ Rouen Normandie, INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux UMR 6634, Rouen F-76000, France
| | - Baishakhi Mazumder
- Department of Material Design and Innovation, University at Buffalo, Buffalo, NY 14260, USA
| | - Dennis Meier
- Department of Materials Science and Engineering, NTNU, Norwegian University of Science and Technology, Trondheim 7491, Norway
| | - François Vurpillot
- INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux UMR 6634, Univ Rouen Normandie, INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux UMR 6634, Rouen F-76000, France
| |
Collapse
|
2
|
Sharmila B, Krithika VR, Pal S, Mahesh TS, Lakshmibala S, Balakrishnan V. Tomographic entanglement indicators from NMR experiments. J Chem Phys 2022; 156:154102. [DOI: 10.1063/5.0087032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In recent years, the performance of different entanglement indicators obtained directly from tomograms has been assessed in continuous-variable and hybrid quantum systems. In this paper, we carry out this task in the case of spin systems. We compute the entanglement indicators from actual experimental data obtained from three liquid-state NMR experiments, and compare them with standard entanglement measures calculated from the corresponding density matrices, both experimentally reconstructed and numerically computed. The gross features of entanglement dynamics and spin squeezing properties are found to be reproduced by these entanglement indicators. However, the extent to which these indicators and spin squeezing track the entanglement during time evolution of the multipartite systems in the NMR experiments is very sensitive to the precise nature and strength of interactions as well as the manner in which the full system is partitioned into subsystems. We also use the IBM quantum computer to implement equivalent circuits that capture the dynamics of the multipartite system in one of the NMR experiments and carry out a similar comparative assessment of the performance of tomographic indicators. This exercise shows that these indicators can estimate the degree of entanglement without necessitating detailed state reconstruction procedures, establishing the advantage of the tomographic approach.
Collapse
Affiliation(s)
- B. Sharmila
- Physics, University of Warwick Department of Physics, United Kingdom
- Indian Institute of Technology Madras Department of Physics
| | - V. R. Krithika
- Indian Institute of Science Education and Research Pune, India
| | - Soham Pal
- Indian Institute of Science Education and Research Pune, India
| | - T. S. Mahesh
- Indian Institute of Science Education and Research Pune, India
| | - S. Lakshmibala
- Indian Institute of Technology Madras Department of Physics, India
| | - V. Balakrishnan
- Indian Institute of Technology Madras Department of Physics, India
| |
Collapse
|
3
|
Stender P, Gault B, Schwarz TM, Woods EV, Kim SH, Ott J, Stephenson LT, Schmitz G, Freysoldt C, Kästner J, El-Zoka AA. Status and Direction of Atom Probe Analysis of Frozen Liquids. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2022; 28:1-18. [PMID: 35039105 DOI: 10.1017/s1431927621013994] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Imaging of liquids and cryogenic biological materials by electron microscopy has been recently enabled by innovative approaches for specimen preparation and the fast development of optimized instruments for cryo-enabled electron microscopy (cryo-EM). Yet, cryo-EM typically lacks advanced analytical capabilities, in particular for light elements. With the development of protocols for frozen wet specimen preparation, atom probe tomography (APT) could advantageously complement insights gained by cryo-EM. Here, we report on different approaches that have been recently proposed to enable the analysis of relatively large volumes of frozen liquids from either a flat substrate or the fractured surface of a wire. Both allowed for analyzing water ice layers which are several micrometers thick consisting of pure water, pure heavy water, and aqueous solutions. We discuss the merits of both approaches and prospects for further developments in this area. Preliminary results raise numerous questions, in part concerning the physics underpinning field evaporation. We discuss these aspects and lay out some of the challenges regarding the APT analysis of frozen liquids.
Collapse
Affiliation(s)
- Patrick Stender
- Institute of Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstrasse 3, 70569Stuttgart, Germany
| | - Baptiste Gault
- Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
- Department of Materials, Royal School of Mines, Imperial College London, London, UK
| | - Tim M Schwarz
- Institute of Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstrasse 3, 70569Stuttgart, Germany
| | - Eric V Woods
- Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
| | - Se-Ho Kim
- Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
| | - Jonas Ott
- Institute of Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstrasse 3, 70569Stuttgart, Germany
| | | | - Guido Schmitz
- Institute of Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstrasse 3, 70569Stuttgart, Germany
| | | | - Johannes Kästner
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569Stuttgart, Germany
| | - Ayman A El-Zoka
- Institute of Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstrasse 3, 70569Stuttgart, Germany
| |
Collapse
|
4
|
Gault B, Chiaramonti A, Cojocaru-Mirédin O, Stender P, Dubosq R, Freysoldt C, Makineni SK, Li T, Moody M, Cairney JM. Atom probe tomography. NATURE REVIEWS. METHODS PRIMERS 2021; 1:10.1038/s43586-021-00047-w. [PMID: 37719173 PMCID: PMC10502706 DOI: 10.1038/s43586-021-00047-w] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/01/2021] [Indexed: 09/19/2023]
Abstract
Atom probe tomography (APT) provides three-dimensional compositional mapping with sub-nanometre resolution. The sensitivity of APT is in the range of parts per million for all elements, including light elements such as hydrogen, carbon or lithium, enabling unique insights into the composition of performance-enhancing or lifetime-limiting microstructural features and making APT ideally suited to complement electron-based or X-ray-based microscopies and spectroscopies. Here, we provide an introductory overview of APT ranging from its inception as an evolution of field ion microscopy to the most recent developments in specimen preparation, including for nanomaterials. We touch on data reconstruction, analysis and various applications, including in the geosciences and the burgeoning biological sciences. We review the underpinnings of APT performance and discuss both strengths and limitations of APT, including how the community can improve on current shortcomings. Finally, we look forwards to true atomic-scale tomography with the ability to measure the isotopic identity and spatial coordinates of every atom in an ever wider range of materials through new specimen preparation routes, novel laser pulsing and detector technologies, and full interoperability with complementary microscopy techniques.
Collapse
Affiliation(s)
- Baptiste Gault
- Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
- Department of Materials, Royal School of Mines, Imperial College, London, UK
| | - Ann Chiaramonti
- National Institute of Standards and Technology, Applied Chemicals and Materials Division, Boulder, CO, USA
| | | | - Patrick Stender
- Institute of Materials Science, University of Stuttgart, Stuttgart, Germany
| | - Renelle Dubosq
- Department of Earth and Environmental Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | | | | | - Tong Li
- Institute for Materials, Ruhr-Universität Bochum, Bochum, Germany
| | - Michael Moody
- Department of Materials, University of Oxford, Oxford, UK
| | - Julie M. Cairney
- Australian Centre for Microscopy and Microanalysis, University of Sydney, Sydney, New South Wales, Australia
- School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, New South Wales, Australia
| |
Collapse
|
5
|
Di Russo E, Blum I, Rivalta I, Houard J, Da Costa G, Vurpillot F, Blavette D, Rigutti L. Detecting Dissociation Dynamics of Phosphorus Molecular Ions by Atom Probe Tomography. J Phys Chem A 2020; 124:10977-10988. [PMID: 33348984 DOI: 10.1021/acs.jpca.0c09259] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Dissociation processes involving phosphorus cations were investigated during laser-assisted atom probe tomography of crystalline indium phosphide (InP). This technique not only allows the formation of medium-sized phosphorus cations by means of femtosecond laser pulses under ultrahigh vacuum and high electric field conditions but also allows one to study the time-resolved dissociation dynamics. Data reveal the formation of cations up to P232+ and their subsequent dissociation into two smaller Pk+ cations (k > 2). The use of a time- and position-sensitive detector combined with numerical calculations provided information related to the molecule orientation, decay time, and kinetic energy release during dissociation phenomena. Results suggest that the dissociation processes are most likely due to the emission of Pk2+ cations in excited states and their subsequent decay in low field regions during their flight toward the detector. This study provides operative guidelines to obtain information on dissociation processes using a tomographic atom probe as a reaction microscope and indicates the current capabilities and limitations of such an approach.
Collapse
Affiliation(s)
- E Di Russo
- UNIROUEN, INSA Rouen, CNRS, Groupe de Physique des Matériaux, Normandie Université, 76000 Rouen, France
| | - I Blum
- UNIROUEN, INSA Rouen, CNRS, Groupe de Physique des Matériaux, Normandie Université, 76000 Rouen, France
| | - I Rivalta
- Dipartimento di Chimica Industriale "Toso Montanari", ALMA MATER STUDIORUM, Università di Bologna, Viale del Risorgimento 4, 40126 Bologna, Italia.,Univ Lyon, Ens de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342 Lyon, France
| | - J Houard
- UNIROUEN, INSA Rouen, CNRS, Groupe de Physique des Matériaux, Normandie Université, 76000 Rouen, France
| | - G Da Costa
- UNIROUEN, INSA Rouen, CNRS, Groupe de Physique des Matériaux, Normandie Université, 76000 Rouen, France
| | - F Vurpillot
- UNIROUEN, INSA Rouen, CNRS, Groupe de Physique des Matériaux, Normandie Université, 76000 Rouen, France
| | - D Blavette
- UNIROUEN, INSA Rouen, CNRS, Groupe de Physique des Matériaux, Normandie Université, 76000 Rouen, France
| | - L Rigutti
- UNIROUEN, INSA Rouen, CNRS, Groupe de Physique des Matériaux, Normandie Université, 76000 Rouen, France
| |
Collapse
|
6
|
Potential sources of compositional inaccuracy in the atom probe tomography of In xGa 1-xAs. Ultramicroscopy 2019; 210:112918. [PMID: 31918069 DOI: 10.1016/j.ultramic.2019.112918] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 11/29/2019] [Accepted: 12/13/2019] [Indexed: 11/23/2022]
Abstract
With the objective of applying laser-assisted atom probe tomography to compositional analysis within nanoscale InGaAs devices, experimental conditions that may provide an accurate composition estimate were sought by extensively studying an InGaAs blanket film. Overall, the determined arsenic atomic fraction was found to exhibit an electric field dependent deficiency, which was more pronounced at low field conditions. Although the determined group III site-fraction also showed a (weak) field-dependent deficiency at low field conditions, it remained invariant with analysis conditions and in close agreement with the nominal value at higher field. In this study, we investigate and discuss the mechanisms that could potentially contribute to As underestimation. Given the field dependence observed, the phenomena occurring between low and high field conditions are compared. At low field, the tendency of As to field evaporate in significant amounts as multiply charged cluster ions (Asni+ with n as large as 9 and i = 1,2,3) is shown to be a significant source of compositional inaccuracy. These clusters may lead to peak overlap in the mass spectrum (e.g. the peak at 150 Da may represent As42+ or As2+ or both), thereby creating an uncertainty in the quantification. Emitted clusters may also dissociate with the likelihood of neutral generation and multi-hit losses being non-negligible. Experimental studies and density functional theory calculations are presented to characterize cluster stability and its contribution to measurement uncertainty. Under high field conditions, although fewer clusters are detected and the composition appears more accurate, the emergence of two additional mechanisms, i.e., multi-hits and DC evaporation, may degrade the data quality. The challenges in evaluating the impact of all these loss mechanisms are examined in detail. Finally, we show that for InGaAs under UV illumination, due to the laser-tip interaction, the resulting asymmetric electric field distribution across the apex introduces local atomic fraction variations.
Collapse
|
7
|
Zanuttini D, Vurpillot F, Douady J, Jacquet E, Anglade PM, Gervais B. Dissociation of GaN 2+ and AlN 2+ in APT: Electronic structure and stability in strong DC field. J Chem Phys 2018; 149:134310. [PMID: 30292191 DOI: 10.1063/1.5036933] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We investigate from a theoretical point of view the stability of AlN2+ and GaN2+ dications produced under high static electric fields like those reached in Atom Probe Tomography (APT) experiments. By means of quantum chemical calculations of the electronic structure of these molecules, we show that their stability is governed by two independent processes. On the one hand, the spin-orbit coupling allows some molecular excited states to dissociate by inter-system crossing. On the other hand, the action of the electric field lowers the potential energy barrier, which ensures the dication stability in standard conditions. We present a detailed example of field emission dynamics in the specific case of the 11Δ states for a parabolic tip, which captures the essentials of the process by means of a simplified model. We show that the dissociation dynamics of AlN2+ and GaN2+ is completely different despite the strong resemblance of their electronic structure.
Collapse
Affiliation(s)
- D Zanuttini
- Normandie Université, UNIROUEN, INSA Rouen, CNRS, GPM, 76000 Rouen, France
| | - F Vurpillot
- Normandie Université, UNIROUEN, INSA Rouen, CNRS, GPM, 76000 Rouen, France
| | - J Douady
- Normandie Université, ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, UMR 6252, BP 5133, F-14070 Caen Cedex 05, France
| | - E Jacquet
- Normandie Université, ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, UMR 6252, BP 5133, F-14070 Caen Cedex 05, France
| | - P-M Anglade
- Normandie Université, ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, UMR 6252, BP 5133, F-14070 Caen Cedex 05, France
| | - B Gervais
- Normandie Université, ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, UMR 6252, BP 5133, F-14070 Caen Cedex 05, France
| |
Collapse
|
8
|
Zanuttini D, Blum I, di Russo E, Rigutti L, Vurpillot F, Douady J, Jacquet E, Anglade PM, Gervais B. Dissociation of GaN 2+ and AlN 2+ in APT: Analysis of experimental measurements. J Chem Phys 2018; 149:134311. [PMID: 30292204 DOI: 10.1063/1.5037010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The use of a tip-shaped sample for the atom probe tomography technique offers the unique opportunity to analyze the dynamics of molecular ions in strong DC fields. We investigate here the stability of AlN2+ and GaN2+ dications emitted from an Al0.25Ga0.75N sample in a joint theoretical and experimental study. Despite the strong chemical resemblance of these two molecules, we observe only stable AlN2+, while GaN2+ can only be observed as a transient species. We simulate the emission dynamics of these ions on field-perturbed potential energy surfaces obtained from quantum chemical calculations. We show that the dissociation is governed by two independent processes. For all bound states, a mechanical dissociation is induced by the distortion of the potential energy surface in the close vicinity of the emitting tip. In the specific case of GaN2+, the relatively small electric dipole of the dication in its ground 13Σ- and excited 11Δ states induces a weak coupling with the electric field so that the mechanical dissociation into Ga+ + N+ lasts for sufficient time to be observed. By contrast, the AlN2+ mechanical dissociation leads to Al2+ + N which cannot be observed as a correlated event. For some deeply bound singlet excited states, the spin-orbit coupling with lower energy triplet states gives another chance of dissociation by system inter-system crossing with specific patterns observed experimentally in a correlated time of flight map.
Collapse
Affiliation(s)
- D Zanuttini
- Normandie Université, UNIROUEN, INSA Rouen, CNRS, GPM, 76000 Rouen, France
| | - I Blum
- Normandie Université, UNIROUEN, INSA Rouen, CNRS, GPM, 76000 Rouen, France
| | - E di Russo
- Normandie Université, UNIROUEN, INSA Rouen, CNRS, GPM, 76000 Rouen, France
| | - L Rigutti
- Normandie Université, UNIROUEN, INSA Rouen, CNRS, GPM, 76000 Rouen, France
| | - F Vurpillot
- Normandie Université, UNIROUEN, INSA Rouen, CNRS, GPM, 76000 Rouen, France
| | - J Douady
- Normandie Université, ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, UMR 6252, BP 5133, F-14070 Caen Cedex 05, France
| | - E Jacquet
- Normandie Université, ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, UMR 6252, BP 5133, F-14070 Caen Cedex 05, France
| | - P-M Anglade
- Normandie Université, ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, UMR 6252, BP 5133, F-14070 Caen Cedex 05, France
| | - B Gervais
- Normandie Université, ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, UMR 6252, BP 5133, F-14070 Caen Cedex 05, France
| |
Collapse
|
9
|
Self-consistent atom probe tomography reconstructions utilizing electron microscopy. Ultramicroscopy 2018; 195:32-46. [PMID: 30179773 DOI: 10.1016/j.ultramic.2018.08.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 08/15/2018] [Accepted: 08/25/2018] [Indexed: 11/24/2022]
Abstract
Atom probe tomography reconstructions provide valuable information on nanometer-scale compositional variations within materials. As such, the spatial accuracy of the reconstructions is of primary importance for the resulting conclusions to be valid. Here, the use of transmission electron microscopy images before and after atom probe analysis to provide additional information and constraints is examined for a number of different materials. In particular, the consistency between the input reconstruction parameters and the output reconstruction is explored. It is demonstrated that it is possible to generate reconstructions in which the input and known values are completely consistent with the output reconstructions. Yet, it is also found that for all of the datasets examined, a particular power law relationship exists such that, if the image compression factor or detection efficiency is not constrained, a series of similarly spatially accurate reconstructions results. However, if one of these values can be independently assessed, then the other is known as well. Means of incorporating these findings and this general methodology into reconstruction protocols are also discussed.
Collapse
|
10
|
Hiller D, López-Vidrier J, Nomoto K, Wahl M, Bock W, Chlouba T, Trojánek F, Gutsch S, Zacharias M, König D, Malý P, Kopnarski M. Absence of free carriers in silicon nanocrystals grown from phosphorus- and boron-doped silicon-rich oxide and oxynitride. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2018; 9:1501-1511. [PMID: 29977683 PMCID: PMC6009393 DOI: 10.3762/bjnano.9.141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 04/25/2018] [Indexed: 06/08/2023]
Abstract
Phosphorus- and boron-doped silicon nanocrystals (Si NCs) embedded in silicon oxide matrix can be fabricated by plasma-enhanced chemical vapour deposition (PECVD). Conventionally, SiH4 and N2O are used as precursor gasses, which inevitably leads to the incorporation of ≈10 atom % nitrogen, rendering the matrix a silicon oxynitride. Alternatively, SiH4 and O2 can be used, which allows for completely N-free silicon oxide. In this work, we investigate the properties of B- and P-incorporating Si NCs embedded in pure silicon oxide compared to silicon oxynitride by atom probe tomography (APT), low-temperature photoluminescence (PL), transient transmission (TT), and current-voltage (I-V) measurements. The results clearly show that no free carriers, neither from P- nor from B-doping, exist in the Si NCs, although in some configurations charge carriers can be generated by electric field ionization. The absence of free carriers in Si NCs ≤5 nm in diameter despite the presence of P- or B-atoms has severe implications for future applications of conventional impurity doping of Si in sub-10 nm technology nodes.
Collapse
Affiliation(s)
- Daniel Hiller
- Research School of Engineering, Australian National University (ANU), Canberra, Australia
- Laboratory for Nanotechnology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Germany
| | - Julian López-Vidrier
- Laboratory for Nanotechnology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Germany
| | - Keita Nomoto
- The University of Sydney, Faculty of Engineering and Information Technologies, School of Aerospace, Mechanical and Mechatronic Engineering, Sydney, Australia
| | - Michael Wahl
- Institute for Surface and Thin Film Analysis GmbH (IFOS), Kaiserslautern, Germany
| | - Wolfgang Bock
- Institute for Surface and Thin Film Analysis GmbH (IFOS), Kaiserslautern, Germany
| | - Tomáš Chlouba
- Department of Chemical Physics and Optics, Charles University, Prague, Czech Republic
| | - František Trojánek
- Department of Chemical Physics and Optics, Charles University, Prague, Czech Republic
| | - Sebastian Gutsch
- Laboratory for Nanotechnology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Germany
| | - Margit Zacharias
- Laboratory for Nanotechnology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Germany
| | - Dirk König
- Integrated Materials Design Centre (IMDC), University of New South Wales (UNSW), Sydney, Australia
| | - Petr Malý
- Department of Chemical Physics and Optics, Charles University, Prague, Czech Republic
| | - Michael Kopnarski
- Institute for Surface and Thin Film Analysis GmbH (IFOS), Kaiserslautern, Germany
| |
Collapse
|
11
|
Compositional accuracy of atom probe tomography measurements in GaN: Impact of experimental parameters and multiple evaporation events. Ultramicroscopy 2018; 187:126-134. [PMID: 29454890 DOI: 10.1016/j.ultramic.2018.02.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/31/2018] [Accepted: 02/03/2018] [Indexed: 11/23/2022]
Abstract
A systematic study of the biases occurring in the measurement of the composition of GaN by Atom Probe Tomography was carried out, in which the role of surface electric field and laser pulse intensity has been investigated. Our data confirm that the electric field is the main factor influencing the measured composition, which exhibits a deficiency of N at low field and a deficiency of Ga at high field. The deficiency of Ga at high field is interpreted in terms of preferential evaporation of Ga. The detailed analysis of multiple evaporation events reveals that the measured composition is not affected by pile-up phenomena occurring in detection system. The analysis of correlation histograms yields the signature of the production of neutral N2 due to the dissociation of GaN32+ ions. However, the amount of N2 neutral molecules that can be detected cannot account for the N deficiency found at low field. Therefore, we propose that further mechanisms of neutral N evaporation could be represented by dissociation reactions such as GaN+→ Ga++ N and GaN2+→ Ga2++ N.
Collapse
|