Utkur Mirsaidov
Degree: PhD
Position: Associate Professor
Affiliation: NUS – Department of Physics
Research Type: Experiment
Office: S1A-02-01
Email: phyumm@nus.edu.sg
Contact: (65) 6516 5426
Website: https://www.mirsaidov.org/
CA2DM Publications:
2025 |
Jiang, Yingying; Lin, Guoming; Mirsaidov, Utkur Nucleation and crystallization of metal oxides from carbonates Journal Article NANOSCALE, 17 (45), pp. 26194-26202, 2025, ISSN: 2040-3364. @article{ISI:001608691200001, title = {Nucleation and crystallization of metal oxides from carbonates}, author = {Yingying Jiang and Guoming Lin and Utkur Mirsaidov}, doi = {10.1039/d5nr01525a}, times_cited = {0}, issn = {2040-3364}, year = {2025}, date = {2025-11-06}, journal = {NANOSCALE}, volume = {17}, number = {45}, pages = {26194-26202}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {Metal oxides play an important role in catalysis, integrated circuit fabrication, and optical coatings. A common approach for obtaining these oxides is the thermal decomposition of solid precursor templates, among which metal carbonates are the most widely used ones. Despite the importance of the process, the atomic-scale mechanisms governing the transformation of such templates into oxides remain insufficiently understood. Using in situ transmission electron microscopy (TEM), we show that La2(CO3)3 keywords = {}, pubstate = {published}, tppubtype = {article} } Metal oxides play an important role in catalysis, integrated circuit fabrication, and optical coatings. A common approach for obtaining these oxides is the thermal decomposition of solid precursor templates, among which metal carbonates are the most widely used ones. Despite the importance of the process, the atomic-scale mechanisms governing the transformation of such templates into oxides remain insufficiently understood. Using in situ transmission electron microscopy (TEM), we show that La2(CO3)3 |
Wang, Wenhui; Zhu, Mingyun; Erofeev, Ivan; Lin, Guoming; Yin, Kuibo; Sun, Litao; Mirsaidov, Utkur Size-Focusing of Au Nanoparticles through Dissolution-Renucleation Process Imaged with In Situ TEM Journal Article SMALL METHODS, 9 (11), 2025, ISSN: 2366-9608. @article{ISI:001597531200001, title = {Size-Focusing of Au Nanoparticles through Dissolution-Renucleation Process Imaged with In Situ TEM}, author = {Wenhui Wang and Mingyun Zhu and Ivan Erofeev and Guoming Lin and Kuibo Yin and Litao Sun and Utkur Mirsaidov}, doi = {10.1002/smtd.202501033}, times_cited = {0}, issn = {2366-9608}, year = {2025}, date = {2025-10-22}, journal = {SMALL METHODS}, volume = {9}, number = {11}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {The transformation of large polydisperse nanoparticles (NPs) into small monodisperse ones by adding ligands is an important and powerful post-synthesis method for tuning the size and morphology of NPs. However, the mechanism of this widely used process is not well understood. Here, using in situ liquid-phase transmission electron microscopy (TEM), we show that the steps of this transformation are a complete dissolution of the original NPs and a subsequent renucleation and growth of new, smaller, uniformly-sized NPs. This work offers mechanistic insights into the synthesis of monodisperse NPs and highlights the importance of direct imaging in identifying the physical and chemical details of nanoscale processes that occur in a liquid phase.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The transformation of large polydisperse nanoparticles (NPs) into small monodisperse ones by adding ligands is an important and powerful post-synthesis method for tuning the size and morphology of NPs. However, the mechanism of this widely used process is not well understood. Here, using in situ liquid-phase transmission electron microscopy (TEM), we show that the steps of this transformation are a complete dissolution of the original NPs and a subsequent renucleation and growth of new, smaller, uniformly-sized NPs. This work offers mechanistic insights into the synthesis of monodisperse NPs and highlights the importance of direct imaging in identifying the physical and chemical details of nanoscale processes that occur in a liquid phase. |
Saidov, Khakimjon; Aabdin, Zainul; Yan, Hongwei; Pacco, Antoine; Holsteyns, Frank; Mirsaidov, Utkur Controlling Etch Anisotropy of Crystalline Germanium Nanostructures Journal Article SMALL, 21 (40), 2025, ISSN: 1613-6810. @article{ISI:001559862700001, title = {Controlling Etch Anisotropy of Crystalline Germanium Nanostructures}, author = {Khakimjon Saidov and Zainul Aabdin and Hongwei Yan and Antoine Pacco and Frank Holsteyns and Utkur Mirsaidov}, doi = {10.1002/smll.202504357}, times_cited = {0}, issn = {1613-6810}, year = {2025}, date = {2025-08-29}, journal = {SMALL}, volume = {21}, number = {40}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {Orientation-dependent wet chemical etching of crystalline germanium (c-Ge) is essential for the fabrication of next-generation complementary metal oxide semiconductor (CMOS) devices. Here, using a combination of conventional and in situ liquid-phase transmission electron microscopy (TEM) imaging, we reveal the details of the wet etching process of c-Ge nanostructures and identify critical parameters that control the etching rates along different crystalline directions. We demonstrate that etching behavior can be changed from isotropic to anisotropic etching (i.e., from crystal-orientation-independent to orientation-dependent etching) by introducing hydrochloric acid (HCl) into a commonly used hydrogen peroxide (H2O2) etchant. The observations reveal that the relative etching rates along different crystal directions can be tuned by adjusting the HCl concentration, allowing for full control over the etch anisotropy. The study provides important insights into the nanoscale details of the wet etching of c-Ge and presents a new level of control required for the fabrication of advanced nanoelectronic devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Orientation-dependent wet chemical etching of crystalline germanium (c-Ge) is essential for the fabrication of next-generation complementary metal oxide semiconductor (CMOS) devices. Here, using a combination of conventional and in situ liquid-phase transmission electron microscopy (TEM) imaging, we reveal the details of the wet etching process of c-Ge nanostructures and identify critical parameters that control the etching rates along different crystalline directions. We demonstrate that etching behavior can be changed from isotropic to anisotropic etching (i.e., from crystal-orientation-independent to orientation-dependent etching) by introducing hydrochloric acid (HCl) into a commonly used hydrogen peroxide (H2O2) etchant. The observations reveal that the relative etching rates along different crystal directions can be tuned by adjusting the HCl concentration, allowing for full control over the etch anisotropy. The study provides important insights into the nanoscale details of the wet etching of c-Ge and presents a new level of control required for the fabrication of advanced nanoelectronic devices. |
Jiang, Yingying; Tangpakonsab, Parinya (lewis); Genest, Alexander; Rupprechter, Gunther; Mirsaidov, Utkur Operando TEM Study of Partial Oxidation of Methane Over Pd Nanoparticles Journal Article ADVANCED SCIENCE, 12 (43), 2025. @article{ISI:001555295900001, title = {Operando TEM Study of Partial Oxidation of Methane Over Pd Nanoparticles}, author = {Yingying Jiang and Parinya (lewis) Tangpakonsab and Alexander Genest and Gunther Rupprechter and Utkur Mirsaidov}, doi = {10.1002/advs.202507303}, times_cited = {1}, year = {2025}, date = {2025-08-24}, journal = {ADVANCED SCIENCE}, volume = {12}, number = {43}, publisher = {WILEY}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {Methane (CH4), which constitutes over 95% of low-cost and abundantly available natural gas reserves, represents a key feedstock for producing syngas and other value-added chemicals. Developing catalysts capable of efficiently converting CH4 into these chemicals is, therefore, crucial for reducing the dependence on limited crude oil resources. Despite the importance of these conversion reactions, the underlying details of catalyst activity remain elusive. Here, using operando gas-cell transmission electron microscopy, the nanoscale mechanisms of the catalytic partial oxidation of CH4 over Pd nanoparticles (NPs) are explored. The observations show that the onset of the catalytic reaction directly coincides with the transformation of these NPs into robust fragmented Pd-PdO NPs. Density functional theory calculations reveal that the Pd-PdO interface plays a pivotal role in optimizing the reaction pathway: metallic Pd facilitates CH4 dehydrogenation, while PdO promotes C oxidation. These insights into the active structures of catalysts under working conditions provide a foundation for the rational design of high-performance catalysts.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Methane (CH4), which constitutes over 95% of low-cost and abundantly available natural gas reserves, represents a key feedstock for producing syngas and other value-added chemicals. Developing catalysts capable of efficiently converting CH4 into these chemicals is, therefore, crucial for reducing the dependence on limited crude oil resources. Despite the importance of these conversion reactions, the underlying details of catalyst activity remain elusive. Here, using operando gas-cell transmission electron microscopy, the nanoscale mechanisms of the catalytic partial oxidation of CH4 over Pd nanoparticles (NPs) are explored. The observations show that the onset of the catalytic reaction directly coincides with the transformation of these NPs into robust fragmented Pd-PdO NPs. Density functional theory calculations reveal that the Pd-PdO interface plays a pivotal role in optimizing the reaction pathway: metallic Pd facilitates CH4 dehydrogenation, while PdO promotes C oxidation. These insights into the active structures of catalysts under working conditions provide a foundation for the rational design of high-performance catalysts. |
Deng, Kerong; Gupta, Tushar; Lin, Guoming; Mirsaidov, Utkur Multistep Nucleation of High-Entropy Alloy Nanoparticles Journal Article NANO LETTERS, 25 (31), pp. 11921-11928, 2025, ISSN: 1530-6984. @article{ISI:001534240100001, title = {Multistep Nucleation of High-Entropy Alloy Nanoparticles}, author = {Kerong Deng and Tushar Gupta and Guoming Lin and Utkur Mirsaidov}, doi = {10.1021/acs.nanolett.5c02464}, times_cited = {0}, issn = {1530-6984}, year = {2025}, date = {2025-07-23}, journal = {NANO LETTERS}, volume = {25}, number = {31}, pages = {11921-11928}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {High-entropy alloy (HEA) nanoparticles (NPs) represent a promising class of materials with potential applications in catalysis and energy storage. Therefore, a fundamental understanding of their formation is essential for tailoring and optimizing their properties for such uses. Despite their significance, the nanoscale mechanisms underlying the nucleation and growth of HEA NPs remain poorly understood. Here, we employ in situ transmission electron microscopy (TEM) to elucidate the nanoscale steps involved in the thermal-reduction-based synthesis of FeCoNiRhPt HEA NPs directly from the precursor. Our observations reveal that the formation of these NPs proceeds through a sequential alloying process: it begins with the burst nucleation of amorphous RhPt (a-RhPt) clusters, which then crystallize into c-RhPt alloy NPs. Subsequently, these crystalline NPs incorporate Fe, Co, and Ni to transform them into stable HEA NPs. Understanding the intermediate stages in the formation of HEA alloys provides important insights that extend to the broader field of multimetallic material synthesis.}, keywords = {}, pubstate = {published}, tppubtype = {article} } High-entropy alloy (HEA) nanoparticles (NPs) represent a promising class of materials with potential applications in catalysis and energy storage. Therefore, a fundamental understanding of their formation is essential for tailoring and optimizing their properties for such uses. Despite their significance, the nanoscale mechanisms underlying the nucleation and growth of HEA NPs remain poorly understood. Here, we employ in situ transmission electron microscopy (TEM) to elucidate the nanoscale steps involved in the thermal-reduction-based synthesis of FeCoNiRhPt HEA NPs directly from the precursor. Our observations reveal that the formation of these NPs proceeds through a sequential alloying process: it begins with the burst nucleation of amorphous RhPt (a-RhPt) clusters, which then crystallize into c-RhPt alloy NPs. Subsequently, these crystalline NPs incorporate Fe, Co, and Ni to transform them into stable HEA NPs. Understanding the intermediate stages in the formation of HEA alloys provides important insights that extend to the broader field of multimetallic material synthesis. |
Lin, Guoming; Mirsaidov, Utkur Encapsulation of Metal Nanoparticles by Metal-Organic Framework Imaged with In Situ Liquid Phase Transmission Electron Microscopy Journal Article ADVANCED SCIENCE, 12 (25), 2025. @article{ISI:001468850000001, title = {Encapsulation of Metal Nanoparticles by Metal-Organic Framework Imaged with In Situ Liquid Phase Transmission Electron Microscopy}, author = {Guoming Lin and Utkur Mirsaidov}, doi = {10.1002/advs.202500984}, times_cited = {0}, year = {2025}, date = {2025-04-17}, journal = {ADVANCED SCIENCE}, volume = {12}, number = {25}, publisher = {WILEY}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {Metal nanoparticle@metal-organic framework (NP@MOF) composites hold promise for potential applications in gas storage, catalysis, sensing, environmental monitoring, and biomedicine. Despite their importance, details of how MOFs encapsulate the NPs to form NP@MOF hybrid nanostructures are largely unexplored. Here, using ultra-low electron-flux in situ liquid phase transmission electron microscopy (LP-TEM), the encapsulation of Au NPs with zeolitic imidazolate framework-8 (ZIF-8) is visualized. These observations reveal that the speeds at which MOFs nucleate on the NP's surface impact the shell's shape. At low concentrations of MOF precursor, NPs are encapsulated with well-defined single-crystalline MOF shells, while at high concentrations, MOFs tend to nucleate and grow from multiple sites on the NP surface, resulting in irregularly shaped polycrystalline MOF shells. This approach, which uses a very low electron flux to image the synthesis of Au@ZIF-8 nanostructures, can be extended to imaging crucial processes in many other beam-sensitive materials and help design hybrid systems for a broad range of applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Metal nanoparticle@metal-organic framework (NP@MOF) composites hold promise for potential applications in gas storage, catalysis, sensing, environmental monitoring, and biomedicine. Despite their importance, details of how MOFs encapsulate the NPs to form NP@MOF hybrid nanostructures are largely unexplored. Here, using ultra-low electron-flux in situ liquid phase transmission electron microscopy (LP-TEM), the encapsulation of Au NPs with zeolitic imidazolate framework-8 (ZIF-8) is visualized. These observations reveal that the speeds at which MOFs nucleate on the NP's surface impact the shell's shape. At low concentrations of MOF precursor, NPs are encapsulated with well-defined single-crystalline MOF shells, while at high concentrations, MOFs tend to nucleate and grow from multiple sites on the NP surface, resulting in irregularly shaped polycrystalline MOF shells. This approach, which uses a very low electron flux to image the synthesis of Au@ZIF-8 nanostructures, can be extended to imaging crucial processes in many other beam-sensitive materials and help design hybrid systems for a broad range of applications. |
Jiang, Yingying; Wong, Zicong Marvin; Yan, Hongwei; Tan, Teck Leong; Mirsaidov, Utkur Revealing Multistep Phase Separation in Metal Alloy Nanoparticles with In Situ Transmission Electron Microscopy Journal Article ACS NANO, 19 (3), pp. 3886-3894, 2025, ISSN: 1936-0851. @article{ISI:001396476700001, title = {Revealing Multistep Phase Separation in Metal Alloy Nanoparticles with \textit{In Situ} Transmission Electron Microscopy}, author = {Yingying Jiang and Zicong Marvin Wong and Hongwei Yan and Teck Leong Tan and Utkur Mirsaidov}, doi = {10.1021/acsnano.4c16095}, times_cited = {5}, issn = {1936-0851}, year = {2025}, date = {2025-01-14}, journal = {ACS NANO}, volume = {19}, number = {3}, pages = {3886-3894}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Phase separation plays a crucial role in many natural and industrial processes, such as the formation of clouds and minerals and the distillation of crude oil. In metals and alloys, phase separation is an important approach often utilized to improve their mechanical strength for use in construction, automobile, and aerospace manufacturing. Despite its importance in many processes, the atomic details of phase separation are largely unknown. In particular, it is unclear how a different crystal phase emerges from the parent alloy. Here, using real-time in situ transmission electron microscopy, we describe the stages of the phase separation in face-centered cubic (fcc) AuRu alloy nanoparticles, resulting in a Ru phase with a hexagonal close-packed (hcp) crystal structure. Our observation reveals that the hcp Ru phase forms in two steps: the spinodal decomposition of the alloy produces metastable fcc Ru clusters, and as they grow larger, these clusters transform into hcp Ru domains. Our calculations indicate that the primary reason for the fcc-to-hcp transformation is the size-dependent competition between the interfacial and bulk energies of Ru domains. These insights into elusive, transient steps in the phase separation of alloys can aid in engineering nanomaterials with unconventional phases.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Phase separation plays a crucial role in many natural and industrial processes, such as the formation of clouds and minerals and the distillation of crude oil. In metals and alloys, phase separation is an important approach often utilized to improve their mechanical strength for use in construction, automobile, and aerospace manufacturing. Despite its importance in many processes, the atomic details of phase separation are largely unknown. In particular, it is unclear how a different crystal phase emerges from the parent alloy. Here, using real-time in situ transmission electron microscopy, we describe the stages of the phase separation in face-centered cubic (fcc) AuRu alloy nanoparticles, resulting in a Ru phase with a hexagonal close-packed (hcp) crystal structure. Our observation reveals that the hcp Ru phase forms in two steps: the spinodal decomposition of the alloy produces metastable fcc Ru clusters, and as they grow larger, these clusters transform into hcp Ru domains. Our calculations indicate that the primary reason for the fcc-to-hcp transformation is the size-dependent competition between the interfacial and bulk energies of Ru domains. These insights into elusive, transient steps in the phase separation of alloys can aid in engineering nanomaterials with unconventional phases. |
2024 |
Erofeev, Ivan; Hartanto, Antony Winata; Khan, Muhaimin Mareum; Deng, Kerong; Kumar, Krishna; Aabdin, Zainul; Tjiu, Weng Weei; Zhang, Mingsheng; Pacco, Antoine; Philipsen, Harold; Chowdhuri, Angshuman Ray; Huynh, Han Vinh; Holsteyns, Frank; Mirsaidov, Utkur Digital Etching of Molybdenum Interconnects Using Plasma Oxidation Journal Article ADVANCED MATERIALS INTERFACES, 12 (1), 2024, ISSN: 2196-7350. @article{ISI:001357050400001, title = {Digital Etching of Molybdenum Interconnects Using Plasma Oxidation}, author = {Ivan Erofeev and Antony Winata Hartanto and Muhaimin Mareum Khan and Kerong Deng and Krishna Kumar and Zainul Aabdin and Weng Weei Tjiu and Mingsheng Zhang and Antoine Pacco and Harold Philipsen and Angshuman Ray Chowdhuri and Han Vinh Huynh and Frank Holsteyns and Utkur Mirsaidov}, doi = {10.1002/admi.202400558}, times_cited = {2}, issn = {2196-7350}, year = {2024}, date = {2024-11-12}, journal = {ADVANCED MATERIALS INTERFACES}, volume = {12}, number = {1}, publisher = {WILEY}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {Molybdenum (Mo) has a high potential of becoming the material of choice for sub-10 nm scale metal structures in future integrated circuits (ICs). Manufacturing at this scale requires exceptional precision and consistency, so many metal processing techniques must be reconsidered. In particular, present direct wet chemical etching methods produce anisotropic etching profiles with significant surface roughness, which can be detrimental to device performance. Here, it is shown that polycrystalline Mo nanowires can be etched uniformly using a cyclic two-step "digital" method: the metal surface is first oxidized with isotropic oxygen plasma to form a layer of MoO3, which is then selectively removed using either wet chemical or dry isotropic plasma etching. These two steps are repeated in cycles until the intended metal recess is achieved. High uniformity of plasma oxidation defines the etching uniformity, and small metal recess per cycle (typically 1-2 nm) provides precise control over the etching depth. This method can replace wet etching where high etching precision is needed, enabling the reliable manufacturing of nanoscale metal interconnects.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molybdenum (Mo) has a high potential of becoming the material of choice for sub-10 nm scale metal structures in future integrated circuits (ICs). Manufacturing at this scale requires exceptional precision and consistency, so many metal processing techniques must be reconsidered. In particular, present direct wet chemical etching methods produce anisotropic etching profiles with significant surface roughness, which can be detrimental to device performance. Here, it is shown that polycrystalline Mo nanowires can be etched uniformly using a cyclic two-step "digital" method: the metal surface is first oxidized with isotropic oxygen plasma to form a layer of MoO3, which is then selectively removed using either wet chemical or dry isotropic plasma etching. These two steps are repeated in cycles until the intended metal recess is achieved. High uniformity of plasma oxidation defines the etching uniformity, and small metal recess per cycle (typically 1-2 nm) provides precise control over the etching depth. This method can replace wet etching where high etching precision is needed, enabling the reliable manufacturing of nanoscale metal interconnects. |
Deng, Kerong; Erofeev, Ivan; Chowdhuri, Angshuman Ray; Philipsen, Harold; Aabdin, Zainul; Hartanto, Antony Winata; Tjiu, Weng Weei; Zhang, Mingsheng; Fernando, Devshan; Saidov, Khakimjon; Kumar, Krishna; Pacco, Antoine; Holsteyns, Frank; Huynh, Han Vinh; Mirsaidov, Utkur Nanoscale Wet Etching of Molybdenum Interconnects with Organic Solutions Journal Article SMALL, 20 (51), 2024, ISSN: 1613-6810. @article{ISI:001337998600001, title = {Nanoscale Wet Etching of Molybdenum Interconnects with Organic Solutions}, author = {Kerong Deng and Ivan Erofeev and Angshuman Ray Chowdhuri and Harold Philipsen and Zainul Aabdin and Antony Winata Hartanto and Weng Weei Tjiu and Mingsheng Zhang and Devshan Fernando and Khakimjon Saidov and Krishna Kumar and Antoine Pacco and Frank Holsteyns and Han Vinh Huynh and Utkur Mirsaidov}, doi = {10.1002/smll.202406713}, times_cited = {1}, issn = {1613-6810}, year = {2024}, date = {2024-10-22}, journal = {SMALL}, volume = {20}, number = {51}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {Molybdenum (Mo) has emerged as a promising material for advanced semiconductor devices, especially in the design and fabrication of interconnects requiring sub-10 nm metal nanostructures. However, current wet etching methods for Mo using aqueous solutions struggle to achieve smooth etching profiles at such scales. To address this problem, we explore wet chemical etching of patterned Mo nanowires (NWs) using an organic solution: ceric ammonium nitrate (CAN) dissolved in acetonitrile (ACN). In this study, we demonstrate two distinct etching pathways by controlling the reaction temperature: i) digital cyclic scheme at room temperature, with a self-limiting Mo recess per cycle of approximate to 1.6 nm, and ii) direct etching at elevated temperature (60 degrees C), with a time-controlled Mo recess of approximate to 2 nm min-1. These methods not only offer a highly controllable nanoscale Mo etching but also ensure smooth and uniform etching profiles independent of the crystal grain orientation of the metal.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molybdenum (Mo) has emerged as a promising material for advanced semiconductor devices, especially in the design and fabrication of interconnects requiring sub-10 nm metal nanostructures. However, current wet etching methods for Mo using aqueous solutions struggle to achieve smooth etching profiles at such scales. To address this problem, we explore wet chemical etching of patterned Mo nanowires (NWs) using an organic solution: ceric ammonium nitrate (CAN) dissolved in acetonitrile (ACN). In this study, we demonstrate two distinct etching pathways by controlling the reaction temperature: i) digital cyclic scheme at room temperature, with a self-limiting Mo recess per cycle of approximate to 1.6 nm, and ii) direct etching at elevated temperature (60 degrees C), with a time-controlled Mo recess of approximate to 2 nm min-1. These methods not only offer a highly controllable nanoscale Mo etching but also ensure smooth and uniform etching profiles independent of the crystal grain orientation of the metal. |
Erofeev, Ivan; Saidov, Khakimjon; Baraissov, Zhaslan; Yan, Hongwei; Maurice, Jean-Luc; Panciera, Federico; Mirsaidov, Utkur 3D Shape Reconstruction of Ge Nanowires during Vapor-Liquid-Solid Growth under Modulating Electric Field Journal Article ACS NANO, 18 (34), pp. 22855-22863, 2024, ISSN: 1936-0851. @article{ISI:001289867600001, title = {3D Shape Reconstruction of Ge Nanowires during Vapor-Liquid-Solid Growth under Modulating Electric Field}, author = {Ivan Erofeev and Khakimjon Saidov and Zhaslan Baraissov and Hongwei Yan and Jean-Luc Maurice and Federico Panciera and Utkur Mirsaidov}, doi = {10.1021/acsnano.4c00087}, times_cited = {4}, issn = {1936-0851}, year = {2024}, date = {2024-08-12}, journal = {ACS NANO}, volume = {18}, number = {34}, pages = {22855-22863}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Bottom-up growth offers precise control over the structure and geometry of semiconductor nanowires (NWs), enabling a wide range of possible shapes and seamless heterostructures for applications in nanophotonics and electronics. The most common vapor-liquid-solid (VLS) growth method features a complex interaction between the liquid metal catalyst droplet and the anisotropic structure of the crystalline NW, and the growth is mainly orchestrated by the triple-phase line (TPL). Despite the intrinsic mismatch between the droplet and the NW symmetries, its discussion has been largely avoided because of its complexity, which has led to the situation when multiple observed phenomena such as NW axial asymmetry or the oscillating truncation at the TPL still lack detailed explanation. The introduction of an electric field control of the droplet has opened even more questions, which cannot be answered without properly addressing three-dimensional (3D) structure and morphology of the NW and the droplet. This work describes the details of electric-field-controlled VLS growth of germanium (Ge) NWs using environmental transmission electron microscopy (ETEM). We perform TEM tomography of the droplet-NW system during an unperturbed growth, then track its evolution while modulating the bias potential. Using 3D finite element method (FEM) modeling and crystallographic considerations, we provide a detailed and consistent mechanism for VLS growth, which naturally explains the observed asymmetries and features of a growing NW based on its crystal structure. Our findings provide a solid framework for the fabrication of complex 3D semiconductor nanostructures with ultimate control over their morphology.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Bottom-up growth offers precise control over the structure and geometry of semiconductor nanowires (NWs), enabling a wide range of possible shapes and seamless heterostructures for applications in nanophotonics and electronics. The most common vapor-liquid-solid (VLS) growth method features a complex interaction between the liquid metal catalyst droplet and the anisotropic structure of the crystalline NW, and the growth is mainly orchestrated by the triple-phase line (TPL). Despite the intrinsic mismatch between the droplet and the NW symmetries, its discussion has been largely avoided because of its complexity, which has led to the situation when multiple observed phenomena such as NW axial asymmetry or the oscillating truncation at the TPL still lack detailed explanation. The introduction of an electric field control of the droplet has opened even more questions, which cannot be answered without properly addressing three-dimensional (3D) structure and morphology of the NW and the droplet. This work describes the details of electric-field-controlled VLS growth of germanium (Ge) NWs using environmental transmission electron microscopy (ETEM). We perform TEM tomography of the droplet-NW system during an unperturbed growth, then track its evolution while modulating the bias potential. Using 3D finite element method (FEM) modeling and crystallographic considerations, we provide a detailed and consistent mechanism for VLS growth, which naturally explains the observed asymmetries and features of a growing NW based on its crystal structure. Our findings provide a solid framework for the fabrication of complex 3D semiconductor nanostructures with ultimate control over their morphology. |
Erofeev, Ivan; Hartanto, Antony Winata; Saidov, Khakimjon; Aabdin, Zainul; Pacco, Antoine; Philipsen, Harold; Tjiu, Weng Weei; Hui, Hui Kim; Holsteyns, Frank; Mirsaidov, Utkur Solving the Annealing of Mo Interconnects for Next-Gen Integrated Circuits Journal Article ADVANCED ELECTRONIC MATERIALS, 10 (9), 2024, ISSN: 2199-160X. @article{ISI:001253872900001, title = {Solving the Annealing of Mo Interconnects for Next-Gen Integrated Circuits}, author = {Ivan Erofeev and Antony Winata Hartanto and Khakimjon Saidov and Zainul Aabdin and Antoine Pacco and Harold Philipsen and Weng Weei Tjiu and Hui Kim Hui and Frank Holsteyns and Utkur Mirsaidov}, doi = {10.1002/aelm.202400035}, times_cited = {7}, issn = {2199-160X}, year = {2024}, date = {2024-06-24}, journal = {ADVANCED ELECTRONIC MATERIALS}, volume = {10}, number = {9}, publisher = {WILEY}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {Recent surge in demand for computational power combined with strict constraints on energy consumption requires persistent increase in the density of transistors and memory cells in integrated circuits. Metal interconnects in their current form struggle to follow the size downscaling due to materials limitations at the nanoscale, causing severe performance losses. Next-generation interconnects need new materials, and molybdenum (Mo) is considered the best choice, offering low resistivity, good scalability, and barrierless integration at a low cost. However, it requires annealing at temperatures far exceeding the currently accepted limit. In this work, the challenges of high-temperature annealing of patterned Mo nanowires are looked into, and a new approach is presented to overcome them. It is demonstrated that while a conventional annealing process improves the average grain size, it can also reduce the cross-section area, thus increasing the resistivity. Using high-resolution transmission electron microscopy (TEM) with in situ heating, the evolution of structural features in real time is directly observed. Using insights from these experiments, a cyclic pulsed annealing method is developed, and it is shown that the desired grain structure is achieved in only a few seconds, without forming the surface grooves. These findings can radically facilitate Mo integration, boosting the efficiency of future integrated circuits.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Recent surge in demand for computational power combined with strict constraints on energy consumption requires persistent increase in the density of transistors and memory cells in integrated circuits. Metal interconnects in their current form struggle to follow the size downscaling due to materials limitations at the nanoscale, causing severe performance losses. Next-generation interconnects need new materials, and molybdenum (Mo) is considered the best choice, offering low resistivity, good scalability, and barrierless integration at a low cost. However, it requires annealing at temperatures far exceeding the currently accepted limit. In this work, the challenges of high-temperature annealing of patterned Mo nanowires are looked into, and a new approach is presented to overcome them. It is demonstrated that while a conventional annealing process improves the average grain size, it can also reduce the cross-section area, thus increasing the resistivity. Using high-resolution transmission electron microscopy (TEM) with in situ heating, the evolution of structural features in real time is directly observed. Using insights from these experiments, a cyclic pulsed annealing method is developed, and it is shown that the desired grain structure is achieved in only a few seconds, without forming the surface grooves. These findings can radically facilitate Mo integration, boosting the efficiency of future integrated circuits. |
2023 |
Yang, Kou; Hu, Zhitao; Li, Xiaolai; Nikolaev, Konstantin; Hong, Gan Kai; Mamchik, Natalia; Erofeev, Ivan; Mirsaidov, Utkur M; Neto, Antonio Castro H; Blackwood, Daniel J; Shchukin, Dmitry G; Trushin, Maxim; Novoselov, Kostya S; Andreeva, Daria V Graphene oxide-polyamine preprogrammable nanoreactors with sensing capability for corrosion protection of materials Journal Article PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 120 (35), 2023, ISSN: 0027-8424. @article{ISI:001112759000007, title = {Graphene oxide-polyamine preprogrammable nanoreactors with sensing capability for corrosion protection of materials}, author = {Kou Yang and Zhitao Hu and Xiaolai Li and Konstantin Nikolaev and Gan Kai Hong and Natalia Mamchik and Ivan Erofeev and Utkur M Mirsaidov and Antonio Castro H Neto and Daniel J Blackwood and Dmitry G Shchukin and Maxim Trushin and Kostya S Novoselov and Daria V Andreeva}, doi = {10.1073/pnas.2307618120}, times_cited = {9}, issn = {0027-8424}, year = {2023}, date = {2023-08-21}, journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, volume = {120}, number = {35}, publisher = {NATL ACAD SCIENCES}, address = {2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA}, abstract = {Corrosion is one of the major issues for sustainable manufacturing globally. The annual global cost of corrosion is US$2.5 trillion (approximately 3.4% of the world's GDP). The traditional ways of corrosion protection (such as barriers or inhibiting) are either not very effective (in the case of barrier protection) or excessively expensive (inhibiting). Here, we demonstrate a concept of nanoreactors, which are able to controllably release or adsorb protons or hydroxides directly on corrosion sites, hence, selectively regulating the corrosion reactions. A single nanoreactor comprises a nano compartment wrapped around by a pH-sensing membrane represented, respectively, by a halloysite nanotube and a graphene oxide/polyamine envelope. A nanoreactor response is determined by the change of a signaling pH on a given corrosion site. The nanoreactors are self-assembled and suitable for mass line production. The concept creates sustainable technology for developing smart anticorrosion coatings, which are nontoxic, selective, and inexpensive.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Corrosion is one of the major issues for sustainable manufacturing globally. The annual global cost of corrosion is US$2.5 trillion (approximately 3.4% of the world's GDP). The traditional ways of corrosion protection (such as barriers or inhibiting) are either not very effective (in the case of barrier protection) or excessively expensive (inhibiting). Here, we demonstrate a concept of nanoreactors, which are able to controllably release or adsorb protons or hydroxides directly on corrosion sites, hence, selectively regulating the corrosion reactions. A single nanoreactor comprises a nano compartment wrapped around by a pH-sensing membrane represented, respectively, by a halloysite nanotube and a graphene oxide/polyamine envelope. A nanoreactor response is determined by the change of a signaling pH on a given corrosion site. The nanoreactors are self-assembled and suitable for mass line production. The concept creates sustainable technology for developing smart anticorrosion coatings, which are nontoxic, selective, and inexpensive. |