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:
2023 |
Saidov, Khakimjon; Erofeev, Ivan; Aabdin, Zainul; Pacco, Antoine; Philipsen, Harold; Hartanto, Antony Winata; Chen, Yifan; Yan, Hongwei; Tjiu, Weng Weei; Holsteyns, Frank; Mirsaidov, Utkur Controlled Stepwise Wet Etching of Polycrystalline Mo Nanowires Journal Article ADVANCED FUNCTIONAL MATERIALS, 34 (12), 2023, ISSN: 1616-301X. @article{ISI:001121643300001, title = {Controlled Stepwise Wet Etching of Polycrystalline Mo Nanowires}, author = {Khakimjon Saidov and Ivan Erofeev and Zainul Aabdin and Antoine Pacco and Harold Philipsen and Antony Winata Hartanto and Yifan Chen and Hongwei Yan and Weng Weei Tjiu and Frank Holsteyns and Utkur Mirsaidov}, doi = {10.1002/adfm.202310838}, times_cited = {0}, issn = {1616-301X}, year = {2023}, date = {2023-12-12}, journal = {ADVANCED FUNCTIONAL MATERIALS}, volume = {34}, number = {12}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {With the persistent downscaling of integrated circuits, molybdenum (Mo) is currently considered a potential replacement for copper (Cu) as a material for metal interconnects. However, fabricating metal nanostructures with critical dimensions of the order of 10 nm and below is challenging. This is because the very high density of grain boundaries (GBs) results in highly non-uniform surface profiles during direct wet etching. Moreover, wet etching of Mo with conventional aqueous solutions is problematic, as products of Mo oxidation have different solubility in water, which leads to increased surface roughness. Here, a process is shown for achieving a stable and uniform soluble surface layer of Mo oxide by wet oxidation with H2O2 dissolved in IPA at -20 degrees C. The oxide layer is then selectively dissolved, and by repeating the oxidation and dissolution multiple times, a uniform etch profile is demonstrated with a fine control over the metal recess. Ultimately, this presents a method of precise and uniform wet etching for Mo and other metals needed to fabricate complex nanostructures that are critical in developing next-generation electronic devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } With the persistent downscaling of integrated circuits, molybdenum (Mo) is currently considered a potential replacement for copper (Cu) as a material for metal interconnects. However, fabricating metal nanostructures with critical dimensions of the order of 10 nm and below is challenging. This is because the very high density of grain boundaries (GBs) results in highly non-uniform surface profiles during direct wet etching. Moreover, wet etching of Mo with conventional aqueous solutions is problematic, as products of Mo oxidation have different solubility in water, which leads to increased surface roughness. Here, a process is shown for achieving a stable and uniform soluble surface layer of Mo oxide by wet oxidation with H2O2 dissolved in IPA at -20 degrees C. The oxide layer is then selectively dissolved, and by repeating the oxidation and dissolution multiple times, a uniform etch profile is demonstrated with a fine control over the metal recess. Ultimately, this presents a method of precise and uniform wet etching for Mo and other metals needed to fabricate complex nanostructures that are critical in developing next-generation electronic devices. |
Wang, Wenhui; Erofeev, Ivan; He, Ya; Yang, Fangqi; Yan, Hongwei; Lu, Jiong; Mirsaidov, Utkur Direct Observation of Hollow Bimetallic Nanoparticle Formation through Galvanic Replacement and Etching Reactions Journal Article NANO LETTERS, 23 (23), pp. 10725-10730, 2023, ISSN: 1530-6984. @article{ISI:001125314300001, title = {Direct Observation of Hollow Bimetallic Nanoparticle Formation through Galvanic Replacement and Etching Reactions}, author = {Wenhui Wang and Ivan Erofeev and Ya He and Fangqi Yang and Hongwei Yan and Jiong Lu and Utkur Mirsaidov}, doi = {10.1021/acs.nanolett.3c02575}, times_cited = {0}, issn = {1530-6984}, year = {2023}, date = {2023-11-21}, journal = {NANO LETTERS}, volume = {23}, number = {23}, pages = {10725-10730}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Hollow bimetallic nanoparticles (NPs) formed from metal oxide NP templates are widely used catalysts for hydrogen evolution and CO2 reduction reactions. Despite their importance in catalysis, the details of how these NPs form on the NP templates remain unclear. Here, using in situ liquid-phase transmission electron microscopy (TEM) imaging, we describe the conversion of Cu2O template NPs to hollow PdCu NPs. Our observations show that a polycrystalline PdCu shell forms on the surface of the template via a galvanic replacement reaction while the template undergoes anisotropic etching. This study provides important insights into the synthesis of hollow metallic nanostructures from metal oxide templates.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Hollow bimetallic nanoparticles (NPs) formed from metal oxide NP templates are widely used catalysts for hydrogen evolution and CO2 reduction reactions. Despite their importance in catalysis, the details of how these NPs form on the NP templates remain unclear. Here, using in situ liquid-phase transmission electron microscopy (TEM) imaging, we describe the conversion of Cu2O template NPs to hollow PdCu NPs. Our observations show that a polycrystalline PdCu shell forms on the surface of the template via a galvanic replacement reaction while the template undergoes anisotropic etching. This study provides important insights into the synthesis of hollow metallic nanostructures from metal oxide templates. |
Kazzi, Salim El; Lum, Ya Woon; Erofeev, Ivan; Vajandar, Saumitra; Pasko, Sergej; Krotkus, Simonas; Conran, Ben; Whear, Oliver; Osipowicz, Thomas; Mirsaidov, Utkur Assessing Ultrathin Wafer-Scale WS2 as a Diffusion Barrier for Cu Interconnects Journal Article ACS APPLIED ELECTRONIC MATERIALS, 5 (9), pp. 5074-5081, 2023. @article{ISI:001062611700001, title = {Assessing Ultrathin Wafer-Scale WS_{2} as a Diffusion Barrier for Cu Interconnects}, author = {Salim El Kazzi and Ya Woon Lum and Ivan Erofeev and Saumitra Vajandar and Sergej Pasko and Simonas Krotkus and Ben Conran and Oliver Whear and Thomas Osipowicz and Utkur Mirsaidov}, doi = {10.1021/acsaelm.3c00809}, times_cited = {0}, year = {2023}, date = {2023-09-05}, journal = {ACS APPLIED ELECTRONIC MATERIALS}, volume = {5}, number = {9}, pages = {5074-5081}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {To maintain the scaling trends in the complementary metal oxide semiconductor (CMOS) technology, the thickness of barrier/liner systems used in back-end-of-line (BEOL) fabrication of metal interconnects needs to be sub-2 nm. However, reducing the thickness of the traditional barrier and liner systems necessary for the dimensional scaling of future interconnects is extremely challenging. Hence, ultrathin two-dimensional (2D) transition-metal dichalcogenide (TMD) films can be an alternative to current barrier/liner systems. However, the processes used to grow these films are generally not BEOL-compatible. Here, using the plasma-free metal-organic chemical vapor deposition (MOCVD) process, we grow BEOL-compatible tungsten disulfide (WS2) film, which has a clear advantage over current diffusion barrier/liner systems used in Cu-interconnects. Our results show that these WS2 films not only block Cu diffusion but also reduce the effective resistance of the Cu film by suppressing the grain boundary and interface scattering of electrons.}, keywords = {}, pubstate = {published}, tppubtype = {article} } To maintain the scaling trends in the complementary metal oxide semiconductor (CMOS) technology, the thickness of barrier/liner systems used in back-end-of-line (BEOL) fabrication of metal interconnects needs to be sub-2 nm. However, reducing the thickness of the traditional barrier and liner systems necessary for the dimensional scaling of future interconnects is extremely challenging. Hence, ultrathin two-dimensional (2D) transition-metal dichalcogenide (TMD) films can be an alternative to current barrier/liner systems. However, the processes used to grow these films are generally not BEOL-compatible. Here, using the plasma-free metal-organic chemical vapor deposition (MOCVD) process, we grow BEOL-compatible tungsten disulfide (WS2) film, which has a clear advantage over current diffusion barrier/liner systems used in Cu-interconnects. Our results show that these WS2 films not only block Cu diffusion but also reduce the effective resistance of the Cu film by suppressing the grain boundary and interface scattering of electrons. |
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 = {0}, 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. |
Jiang, Yingying; Lim, Alvin M H; Yan, Hongwei; Zeng, Hua Chun; Mirsaidov, Utkur Phase Segregation in PdCu Alloy Nanoparticles During CO Oxidation Reaction at Atmospheric Pressure Journal Article ADVANCED SCIENCE, 10 (25), 2023. @article{ISI:001018137900001, title = {Phase Segregation in PdCu Alloy Nanoparticles During CO Oxidation Reaction at Atmospheric Pressure}, author = {Yingying Jiang and Alvin M H Lim and Hongwei Yan and Hua Chun Zeng and Utkur Mirsaidov}, doi = {10.1002/advs.202302663}, times_cited = {0}, year = {2023}, date = {2023-06-28}, journal = {ADVANCED SCIENCE}, volume = {10}, number = {25}, publisher = {WILEY}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {Bimetallic nanoparticle (NP) catalysts are widely used in many heterogeneous gas-based reactions because they often outperform their monometallic counterparts. During these reactions, NPs often undergo structural changes, which impact their catalytic activity. Despite the important role of the structure in the catalytic activity, many aspects of how a reactive gaseous environment affects the structure of bimetallic nanocatalysts are still lacking. Here, using gas-cell transmission electron microscopy (TEM), it is shown that during a CO oxidation reaction over PdCu alloy NPs, the selective oxidation of Cu causes the segregation of Cu and transforms the NPs into Pd-CuO NPs. The segregated NPs are very stable and have high activity for the conversion of CO into CO2. Based on the observations, the segregation of Cu from Cu-based alloys during a redox reaction is likely to be general and may have a positive impact on the catalytic activity. Hence, it is believed that similar insights based on direct observation of the reactions under relevant reactive conditions are critical both for understanding and designing high-performance catalysts.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Bimetallic nanoparticle (NP) catalysts are widely used in many heterogeneous gas-based reactions because they often outperform their monometallic counterparts. During these reactions, NPs often undergo structural changes, which impact their catalytic activity. Despite the important role of the structure in the catalytic activity, many aspects of how a reactive gaseous environment affects the structure of bimetallic nanocatalysts are still lacking. Here, using gas-cell transmission electron microscopy (TEM), it is shown that during a CO oxidation reaction over PdCu alloy NPs, the selective oxidation of Cu causes the segregation of Cu and transforms the NPs into Pd-CuO NPs. The segregated NPs are very stable and have high activity for the conversion of CO into CO2. Based on the observations, the segregation of Cu from Cu-based alloys during a redox reaction is likely to be general and may have a positive impact on the catalytic activity. Hence, it is believed that similar insights based on direct observation of the reactions under relevant reactive conditions are critical both for understanding and designing high-performance catalysts. |
Saidov, Khakimjon; Erofeev, Ivan; Yan, Hongwei; Aabdin, Zainul; Mirsaidov, Utkur Direct atomic-scale observation of thermally driven grain-boundary migration associated with triple-junction motion Journal Article PHYSICAL REVIEW MATERIALS, 7 (6), 2023, ISSN: 2475-9953. @article{ISI:001019584400003, title = {Direct atomic-scale observation of thermally driven grain-boundary migration associated with triple-junction motion}, author = {Khakimjon Saidov and Ivan Erofeev and Hongwei Yan and Zainul Aabdin and Utkur Mirsaidov}, doi = {10.1103/PhysRevMaterials.7.063402}, times_cited = {0}, issn = {2475-9953}, year = {2023}, date = {2023-06-20}, journal = {PHYSICAL REVIEW MATERIALS}, volume = {7}, number = {6}, publisher = {AMER PHYSICAL SOC}, address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, abstract = {The internal structure of metals is defined by a complex network of grain boundaries (GBs) and their intersections-triple junctions (TJs). Heat or stress forces GBs to migrate, thus altering many physical properties of the material, and TJs play a key role in this migration as they control GB edges. The GB-TJ interaction strongly depends on the local crystallography, so it can only be properly described at the atomic scale. Although recent direct atomic-scale imaging of GB migration provides some insight into their dynamic behavior, the nanoscale details of the coupled motion of TJs and GBs in a natural nanocrystalline system remain elusive. Here, using in situ transmission electron microscopy (TEM) imaging, we describe the dynamics of the GB-TJ system in a nanocrystalline Co film with mixed fcc and hcp crystal phases during thermal annealing at both the mesoscale and the atomic scale. Our observations reveal that GB evolution proceeds through destabilization and displacement of TJs followed by GB relaxation within the new TJ geometry, which modifies the dihedral angles. This process is mediated by atomic-scale disconnection dynamics, where TJs serve as their sources and sinks. These findings advance our understanding of grain evolution in metal nanostructures, which is crucial for engineering their properties.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The internal structure of metals is defined by a complex network of grain boundaries (GBs) and their intersections-triple junctions (TJs). Heat or stress forces GBs to migrate, thus altering many physical properties of the material, and TJs play a key role in this migration as they control GB edges. The GB-TJ interaction strongly depends on the local crystallography, so it can only be properly described at the atomic scale. Although recent direct atomic-scale imaging of GB migration provides some insight into their dynamic behavior, the nanoscale details of the coupled motion of TJs and GBs in a natural nanocrystalline system remain elusive. Here, using in situ transmission electron microscopy (TEM) imaging, we describe the dynamics of the GB-TJ system in a nanocrystalline Co film with mixed fcc and hcp crystal phases during thermal annealing at both the mesoscale and the atomic scale. Our observations reveal that GB evolution proceeds through destabilization and displacement of TJs followed by GB relaxation within the new TJ geometry, which modifies the dihedral angles. This process is mediated by atomic-scale disconnection dynamics, where TJs serve as their sources and sinks. These findings advance our understanding of grain evolution in metal nanostructures, which is crucial for engineering their properties. |
Jiang, Yingying; Duchamp, Martial; Ang, Shi Jun; Yan, Hongwei; Tan, Teck Leong; Mirsaidov, Utkur Dynamics of the fcc-to-bcc phase transition in single-crystalline PdCu alloy nanoparticles Journal Article NATURE COMMUNICATIONS, 14 (1), 2023. @article{ISI:000914837300005, title = {Dynamics of the fcc-to-bcc phase transition in single-crystalline PdCu alloy nanoparticles}, author = {Yingying Jiang and Martial Duchamp and Shi Jun Ang and Hongwei Yan and Teck Leong Tan and Utkur Mirsaidov}, doi = {10.1038/s41467-022-35325-y}, times_cited = {0}, year = {2023}, date = {2023-01-06}, journal = {NATURE COMMUNICATIONS}, volume = {14}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {Two most common crystal structures in metals and metal alloys are body-centered cubic (bcc) and face-centered cubic (fcc) structures. The phase transitions between these structures play an important role in the production of durable and functional metal alloys. Despite their technological significance, the details of such phase transitions are largely unknown because of the challenges associated with probing these processes. Here, we describe the nanoscopic details of an fcc-to-bcc phase transition in PdCu alloy nanoparticles (NPs) using in situ heating transmission electron microscopy. Our observations reveal that the bcc phase always nucleates from the edge of the fcc NP, and then propagates across the NP by forming a distinct few-atoms-wide coherent bcc-fcc interface. Notably, this interface acts as an intermediate precursor phase for the nucleation of a bcc phase. These insights into the fcc-to-bcc phase transition are important for understanding solid - solid phase transitions in general and can help to tailor the functional properties of metals and their alloys.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two most common crystal structures in metals and metal alloys are body-centered cubic (bcc) and face-centered cubic (fcc) structures. The phase transitions between these structures play an important role in the production of durable and functional metal alloys. Despite their technological significance, the details of such phase transitions are largely unknown because of the challenges associated with probing these processes. Here, we describe the nanoscopic details of an fcc-to-bcc phase transition in PdCu alloy nanoparticles (NPs) using in situ heating transmission electron microscopy. Our observations reveal that the bcc phase always nucleates from the edge of the fcc NP, and then propagates across the NP by forming a distinct few-atoms-wide coherent bcc-fcc interface. Notably, this interface acts as an intermediate precursor phase for the nucleation of a bcc phase. These insights into the fcc-to-bcc phase transition are important for understanding solid - solid phase transitions in general and can help to tailor the functional properties of metals and their alloys. |
2022 |
Yilmaz, Gamze; Yang, Tong; Lim, Kane Jian Hong; Chee, See Wee; Shen, Lei; Mirsaidov, Utkur; Bosman, Michel; Ho, Ghim Wei Rational engineering of metal-organic coordination networks into facet-controlled phosphides for overall water splitting Journal Article ECOMAT, 5 (3), 2022. @article{ISI:000912518600001, title = {Rational engineering of metal-organic coordination networks into facet-controlled phosphides for overall water splitting}, author = {Gamze Yilmaz and Tong Yang and Kane Jian Hong Lim and See Wee Chee and Lei Shen and Utkur Mirsaidov and Michel Bosman and Ghim Wei Ho}, doi = {10.1002/eom2.12312}, times_cited = {0}, year = {2022}, date = {2022-11-30}, journal = {ECOMAT}, volume = {5}, number = {3}, publisher = {WILEY}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {Although transition metal phosphide electrocatalysts display unique electronic structure that serves as functional centers for hydrogen evolution reaction, the synthesis of this class of materials for oxygen evolution remains a challenge due to the complex multielectron transfer pathways and sluggish reaction kinetics. This study details an in-situ modification and transformation of cyanide-bridged nickel-iron (CN-NiFe) organometallic hybrid into the preferential Fe2P phase with prevailing exposed {120(sic)} faceted active centers by leveraging on the facile coordinate cleavage dynamics and compound reactivity of labile metal organic coordination frameworks. The resultant transition metal phosphide attains high electrochemical surface area, low Tafel slope, and low overpotential for the oxygen evolution reaction, while also demonstrating bifunctional electrocatalytic performance for overall water splitting. Comprehensive experimental studies and density functional theory calculations reveal that the exceptional catalytic activity originates from the transformation of framework metallic sites into preferential active sites allows an optimal adsorption of oxygen evolution reaction intermediates.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Although transition metal phosphide electrocatalysts display unique electronic structure that serves as functional centers for hydrogen evolution reaction, the synthesis of this class of materials for oxygen evolution remains a challenge due to the complex multielectron transfer pathways and sluggish reaction kinetics. This study details an in-situ modification and transformation of cyanide-bridged nickel-iron (CN-NiFe) organometallic hybrid into the preferential Fe2P phase with prevailing exposed {120(sic)} faceted active centers by leveraging on the facile coordinate cleavage dynamics and compound reactivity of labile metal organic coordination frameworks. The resultant transition metal phosphide attains high electrochemical surface area, low Tafel slope, and low overpotential for the oxygen evolution reaction, while also demonstrating bifunctional electrocatalytic performance for overall water splitting. Comprehensive experimental studies and density functional theory calculations reveal that the exceptional catalytic activity originates from the transformation of framework metallic sites into preferential active sites allows an optimal adsorption of oxygen evolution reaction intermediates. |
Aabdin, Zainul; Ghosh, Tanmay; Pacco, Antoine; Raj, Sanoj; Do, Hue Thi Bich; Saidov, Khakimjon; Tjiu, Weng Weei; Anand, Utkarsh; Kral, Petr; Holsteyns, Frank; Bosman, Michel; Mirsaidov, Utkur Controlling the Wet-Etch Directionality in Nanostructured Silicon Journal Article ACS APPLIED ELECTRONIC MATERIALS, 4 (11), pp. 5191-5198, 2022. @article{ISI:000885513100001, title = {Controlling the Wet-Etch Directionality in Nanostructured Silicon}, author = {Zainul Aabdin and Tanmay Ghosh and Antoine Pacco and Sanoj Raj and Hue Thi Bich Do and Khakimjon Saidov and Weng Weei Tjiu and Utkarsh Anand and Petr Kral and Frank Holsteyns and Michel Bosman and Utkur Mirsaidov}, doi = {10.1021/acsaelm.2c00824}, times_cited = {0}, year = {2022}, date = {2022-11-12}, journal = {ACS APPLIED ELECTRONIC MATERIALS}, volume = {4}, number = {11}, pages = {5191-5198}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Anisotropic wet etching of crystalline silicon (c-Si) is a key chemical process used in microelectronic device fabrication. Controlled fabrication of c-Si nanostructures requires an understanding of how crystal planes evolve during silicon etching. Here, by imaging KOH wet etching of c-Si nanowires, we show that it is possible to switch the fast-etching direction (i.e., the etch anisotropy) between the Si {100} and {110} crystal planes at will through mechanical agitation of the etchant. Based on molecular dynamics simulations, we attribute this switching to the higher affinity of the Si(OH)4 etch byproducts to the Si {110} planes. These surface-bound byproducts hinder etchant access to the {110} surfaces under stationary etching conditions and thus reduce the etch rate in ⟨110⟩ directions. Most importantly, by cycling through stirred and stationary modes of etching, we can obtain isotropic etch profiles, fabricating high-quality, round Si nanowires with sub-10 nm diameters. Our study provides an important insight into the nanoscale wet etching of Si and demonstrates a new level of control for enabling highly scalable, advanced nanoelectronic devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Anisotropic wet etching of crystalline silicon (c-Si) is a key chemical process used in microelectronic device fabrication. Controlled fabrication of c-Si nanostructures requires an understanding of how crystal planes evolve during silicon etching. Here, by imaging KOH wet etching of c-Si nanowires, we show that it is possible to switch the fast-etching direction (i.e., the etch anisotropy) between the Si {100} and {110} crystal planes at will through mechanical agitation of the etchant. Based on molecular dynamics simulations, we attribute this switching to the higher affinity of the Si(OH)4 etch byproducts to the Si {110} planes. These surface-bound byproducts hinder etchant access to the {110} surfaces under stationary etching conditions and thus reduce the etch rate in ⟨110⟩ directions. Most importantly, by cycling through stirred and stationary modes of etching, we can obtain isotropic etch profiles, fabricating high-quality, round Si nanowires with sub-10 nm diameters. Our study provides an important insight into the nanoscale wet etching of Si and demonstrates a new level of control for enabling highly scalable, advanced nanoelectronic devices. |
Ghosh, Tanmay; Arce-Ramos, Juan Manuel; Li, Wen-Qing; Yan, Hongwei; Chee, See Wee; Genest, Alexander; Mirsaidov, Utkur Periodic structural changes in Pd nanoparticles during oscillatory CO oxidation reaction Journal Article NATURE COMMUNICATIONS, 13 (1), 2022. @article{ISI:000870431200026, title = {Periodic structural changes in Pd nanoparticles during oscillatory CO oxidation reaction}, author = {Tanmay Ghosh and Juan Manuel Arce-Ramos and Wen-Qing Li and Hongwei Yan and See Wee Chee and Alexander Genest and Utkur Mirsaidov}, doi = {10.1038/s41467-022-33304-x}, times_cited = {0}, year = {2022}, date = {2022-10-19}, journal = {NATURE COMMUNICATIONS}, volume = {13}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {Nanoparticle (NP) catalysts are ubiquitous in energy systems, chemical production, and reducing the environmental impact of many industrial processes. Under reactive environments, the availability of catalytically active sites on the NP surface is determined by its dynamic structure. However, atomic-scale insights into how a NP surface reconstructs under reaction conditions and the impact of the reconstruction on catalytic activity are still lacking. Using operando transmission electron microscopy, we show that Pd NPs exhibit periodic round-to-flat transitions altering their facets during CO oxidation reaction at atmospheric pressure and elevated temperatures. This restructuring causes spontaneous oscillations in the conversion of CO to CO2 under constant reaction conditions. Our study reveals that the oscillatory behavior stems from the CO-adsorption-mediated periodic restructuring of the nanocatalysts between high-index-faceted round and low-index-faceted flat shapes. These atomic-scale insights into the dynamic surface properties of NPs under reactive conditions play an important role in the design of high-performance catalysts.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nanoparticle (NP) catalysts are ubiquitous in energy systems, chemical production, and reducing the environmental impact of many industrial processes. Under reactive environments, the availability of catalytically active sites on the NP surface is determined by its dynamic structure. However, atomic-scale insights into how a NP surface reconstructs under reaction conditions and the impact of the reconstruction on catalytic activity are still lacking. Using operando transmission electron microscopy, we show that Pd NPs exhibit periodic round-to-flat transitions altering their facets during CO oxidation reaction at atmospheric pressure and elevated temperatures. This restructuring causes spontaneous oscillations in the conversion of CO to CO2 under constant reaction conditions. Our study reveals that the oscillatory behavior stems from the CO-adsorption-mediated periodic restructuring of the nanocatalysts between high-index-faceted round and low-index-faceted flat shapes. These atomic-scale insights into the dynamic surface properties of NPs under reactive conditions play an important role in the design of high-performance catalysts. |
Wang, Wenhui; Ghosh, Tanmay; Yan, Hongwei; Erofeev, Ivan; Zhang, Kun; Loh, Kian Ping; Mirsaidov, Utkur The Growth Dynamics of Organic-Inorganic Metal Halide Perovskite Films Journal Article JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 144 (39), pp. 17848-17856, 2022, ISSN: 0002-7863. @article{ISI:000861815500001, title = {The Growth Dynamics of Organic-Inorganic Metal Halide Perovskite Films}, author = {Wenhui Wang and Tanmay Ghosh and Hongwei Yan and Ivan Erofeev and Kun Zhang and Kian Ping Loh and Utkur Mirsaidov}, doi = {10.1021/jacs.2c06022}, times_cited = {0}, issn = {0002-7863}, year = {2022}, date = {2022-09-21}, journal = {JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, volume = {144}, number = {39}, pages = {17848-17856}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Organic-inorganic metal halide perovskite films have emerged as potential candidate materials for photoelectric devices because of their superior optoelectronic properties. The performance of these devices depends on the quality of perovskite films defined by their grain size, crystallinity, and absence of pinholes. While solution-based processing is the most cost-effective and scalable approach to producing these films, the impact of the process parameters on the film quality and nanoscale details of these processes are unknown. Specifically, it is unclear how perovskites grow from a liquid precursor to form solid-phase nanocrystals and how these nanocrystals arrange to form a uniform film. Here, using liquid-phase transmission electron microscopy (TEM), we show how perovskite nanocrystals nucleate from a precursor solution and then grow and coalesce to form a polycrystalline film. Furthermore, we show how additives, such as urea, can improve the film crystallinity by increasing perovskite solubility, which induces the dissolution and subsequent redeposition of smaller crystals onto larger grains. Our approach to studying the growth of perovskite films provides an important insight into improving the synthesis of perovskites and other technologically relevant crystalline films.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Organic-inorganic metal halide perovskite films have emerged as potential candidate materials for photoelectric devices because of their superior optoelectronic properties. The performance of these devices depends on the quality of perovskite films defined by their grain size, crystallinity, and absence of pinholes. While solution-based processing is the most cost-effective and scalable approach to producing these films, the impact of the process parameters on the film quality and nanoscale details of these processes are unknown. Specifically, it is unclear how perovskites grow from a liquid precursor to form solid-phase nanocrystals and how these nanocrystals arrange to form a uniform film. Here, using liquid-phase transmission electron microscopy (TEM), we show how perovskite nanocrystals nucleate from a precursor solution and then grow and coalesce to form a polycrystalline film. Furthermore, we show how additives, such as urea, can improve the film crystallinity by increasing perovskite solubility, which induces the dissolution and subsequent redeposition of smaller crystals onto larger grains. Our approach to studying the growth of perovskite films provides an important insight into improving the synthesis of perovskites and other technologically relevant crystalline films. |
Ghosh, Tanmay; Liu, Xiangwen; Sun, Wenming; Chen, Meiqi; Liu, Yuxi; Li, Yadong; Mirsaidov, Utkur Revealing the Origin of Low-Temperature Activity of Ni-Rh Nanostructures during CO Oxidation Reaction with Operando TEM Journal Article ADVANCED SCIENCE, 9 (17), 2022. @article{ISI:000791028300001, title = {Revealing the Origin of Low-Temperature Activity of Ni-Rh Nanostructures during CO Oxidation Reaction with Operando TEM}, author = {Tanmay Ghosh and Xiangwen Liu and Wenming Sun and Meiqi Chen and Yuxi Liu and Yadong Li and Utkur Mirsaidov}, doi = {10.1002/advs.202105599}, times_cited = {0}, year = {2022}, date = {2022-05-05}, journal = {ADVANCED SCIENCE}, volume = {9}, number = {17}, publisher = {WILEY}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {In bimetallic heterostructured nanoparticles (NPs), the synergistic effect between their different metallic components leads to higher catalytic activity compared to the activity of the individual components. However, how the dynamic changes through which these NPs adopt catalytically active structures during a reaction and how the restructuring affects their activity are largely unknown. Here, using operando transmission electron microscopy, structural changes are studied in bimetallic Ni-Rh NPs, comprising of a Ni core whose surface is decorated with smaller Rh NPs, during a CO oxidation reaction. The direct atomic-scale imaging reveals that, under O-2-rich conditions, Ni core partially transforms into NiO, forming a (Ni+NiO)-Rh hollow nanocatalyst with high catalytic activity. Under O-2-poor conditions, Rh NPs alloy with the surface of the core to form a NiRh-alloy surface, and the NPs display significantly lower activity. The theoretical calculations indicate that NiO component that forms only under O-2-rich conditions enhances the activity by preventing the CO poisoning of the nanocatalysts. The results demonstrate that visualizing the structural changes during reactions is indispensable in identifying the origin of catalytic activity. These insights into the dynamic restructuring of NP catalysts under a reactive environment are critical for the rational design of high-performance nanocatalysts.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In bimetallic heterostructured nanoparticles (NPs), the synergistic effect between their different metallic components leads to higher catalytic activity compared to the activity of the individual components. However, how the dynamic changes through which these NPs adopt catalytically active structures during a reaction and how the restructuring affects their activity are largely unknown. Here, using operando transmission electron microscopy, structural changes are studied in bimetallic Ni-Rh NPs, comprising of a Ni core whose surface is decorated with smaller Rh NPs, during a CO oxidation reaction. The direct atomic-scale imaging reveals that, under O-2-rich conditions, Ni core partially transforms into NiO, forming a (Ni+NiO)-Rh hollow nanocatalyst with high catalytic activity. Under O-2-poor conditions, Rh NPs alloy with the surface of the core to form a NiRh-alloy surface, and the NPs display significantly lower activity. The theoretical calculations indicate that NiO component that forms only under O-2-rich conditions enhances the activity by preventing the CO poisoning of the nanocatalysts. The results demonstrate that visualizing the structural changes during reactions is indispensable in identifying the origin of catalytic activity. These insights into the dynamic restructuring of NP catalysts under a reactive environment are critical for the rational design of high-performance nanocatalysts. |
Ghosh, Tanmay; Fritz, Eva-Corinna; Balakrishnan, Deepan; Zhang, Ziyu; Vrancken, Nandi; Anand, Utkarsh; Zhang, Hong; Loh, Duane N; Xu, XiuMei; Holsteyns, Frank; Nijhuis, Christian A; Mirsaidov, Utkur Preventing the Capillary-Induced Collapse of Vertical Nanostructures Journal Article ACS APPLIED MATERIALS & INTERFACES , 14 (4), pp. 5537-5544, 2022, ISSN: 1944-8244. @article{ISI:000768792500068, title = {Preventing the Capillary-Induced Collapse of Vertical Nanostructures }, author = {Tanmay Ghosh and Eva-Corinna Fritz and Deepan Balakrishnan and Ziyu Zhang and Nandi Vrancken and Utkarsh Anand and Hong Zhang and Duane N Loh and XiuMei Xu and Frank Holsteyns and Christian A Nijhuis and Utkur Mirsaidov}, doi = {10.1021/acsami.1c17781}, times_cited = {0}, issn = {1944-8244}, year = {2022}, date = {2022-02-02}, journal = {ACS APPLIED MATERIALS & INTERFACES }, volume = {14}, number = {4}, pages = {5537-5544}, publisher = {AMER CHEMICAL SOC }, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA }, abstract = {Robust processes to fabricate densely packed high-aspect-ratio (HAR) vertical semiconductor nanostructures are important for applications in microelectronics, energy storage and conversion. One of the main challenges in manufacturing these nanostructures is pattern collapse, which is the damage induced by capillary forces from numerous solution-based processes used during their fabrication. Here, using an array of vertical silicon (Si) nanopillars as test structures, we demonstrate that pattern collapse can be greatly reduced by a solution-phase deposition method to coat the nanopillars with self-assembled monolayers (SAMs). As the main cause for pattern collapse is strong adhesion between the nanopillars, we systematically evaluated SAMs with different surface energy components and identified H-bonding between the surfaces to have the largest contribution to the adhesion. The advantage of the solution-phase deposition method is that it can be implemented before any drying step, which causes patterns to collapse. Moreover, after drying, these SAMs can be easily removed using a gentle air-plasma treatment right before the next fabrication step, leaving a clean nanopillar surface behind. Therefore, our approach provides a facile and effective method to prevent the drying-induced pattern collapse in micro- and nanofabrication processes. }, keywords = {}, pubstate = {published}, tppubtype = {article} } Robust processes to fabricate densely packed high-aspect-ratio (HAR) vertical semiconductor nanostructures are important for applications in microelectronics, energy storage and conversion. One of the main challenges in manufacturing these nanostructures is pattern collapse, which is the damage induced by capillary forces from numerous solution-based processes used during their fabrication. Here, using an array of vertical silicon (Si) nanopillars as test structures, we demonstrate that pattern collapse can be greatly reduced by a solution-phase deposition method to coat the nanopillars with self-assembled monolayers (SAMs). As the main cause for pattern collapse is strong adhesion between the nanopillars, we systematically evaluated SAMs with different surface energy components and identified H-bonding between the surfaces to have the largest contribution to the adhesion. The advantage of the solution-phase deposition method is that it can be implemented before any drying step, which causes patterns to collapse. Moreover, after drying, these SAMs can be easily removed using a gentle air-plasma treatment right before the next fabrication step, leaving a clean nanopillar surface behind. Therefore, our approach provides a facile and effective method to prevent the drying-induced pattern collapse in micro- and nanofabrication processes. |
Ghosh, Tanmay; Fritz, Eva-Corinna; Balakrishnan, Deepan; Zhang, Ziyu; Vrancken, Nandi; Anand, Utkarsh; Zhang, Hong; Loh, Duane N; Xu, XiuMei; Holsteyns, Frank; Nijhuis, Christian A; Mirsaidov, Utkur Preventing the Capillary-Induced Collapse of Vertical Nanostructures Journal Article ACS APPLIED MATERIALS & INTERFACES, 14 (4), pp. 5537-5544, 2022, ISSN: 1944-8244. @article{ISI:000745194100001, title = {Preventing the Capillary-Induced Collapse of Vertical Nanostructures}, author = {Tanmay Ghosh and Eva-Corinna Fritz and Deepan Balakrishnan and Ziyu Zhang and Nandi Vrancken and Utkarsh Anand and Hong Zhang and Duane N Loh and XiuMei Xu and Frank Holsteyns and Christian A Nijhuis and Utkur Mirsaidov}, doi = {10.1021/acsami.1c17781}, times_cited = {0}, issn = {1944-8244}, year = {2022}, date = {2022-01-18}, journal = {ACS APPLIED MATERIALS & INTERFACES}, volume = {14}, number = {4}, pages = {5537-5544}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Robust processes to fabricate densely packed high-aspect-ratio (HAR) vertical semiconductor nanostructures are important for applications in microelectronics, energy storage and conversion. One of the main challenges in manufacturing these nanostructures is pattern collapse, which is the damage induced by capillary forces from numerous solution-based processes used during their fabrication. Here, using an array of vertical silicon (Si) nanopillars as test structures, we demonstrate that pattern collapse can be greatly reduced by a solution-phase deposition method to coat the nanopillars with self-assembled monolayers (SAMs). As the main cause for pattern collapse is strong adhesion between the nanopillars, we systematically evaluated SAMs with different surface energy components and identified H-bonding between the surfaces to have the largest contribution to the adhesion. The advantage of the solution-phase deposition method is that it can be implemented before any drying step, which causes patterns to collapse. Moreover, after drying, these SAMs can be easily removed using a gentle air-plasma treatment right before the next fabrication step, leaving a clean nanopillar surface behind. Therefore, our approach provides a facile and effective method to prevent the drying-induced pattern collapse in micro- and nanofabrication processes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Robust processes to fabricate densely packed high-aspect-ratio (HAR) vertical semiconductor nanostructures are important for applications in microelectronics, energy storage and conversion. One of the main challenges in manufacturing these nanostructures is pattern collapse, which is the damage induced by capillary forces from numerous solution-based processes used during their fabrication. Here, using an array of vertical silicon (Si) nanopillars as test structures, we demonstrate that pattern collapse can be greatly reduced by a solution-phase deposition method to coat the nanopillars with self-assembled monolayers (SAMs). As the main cause for pattern collapse is strong adhesion between the nanopillars, we systematically evaluated SAMs with different surface energy components and identified H-bonding between the surfaces to have the largest contribution to the adhesion. The advantage of the solution-phase deposition method is that it can be implemented before any drying step, which causes patterns to collapse. Moreover, after drying, these SAMs can be easily removed using a gentle air-plasma treatment right before the next fabrication step, leaving a clean nanopillar surface behind. Therefore, our approach provides a facile and effective method to prevent the drying-induced pattern collapse in micro- and nanofabrication processes. |
2021 |
Anand, Utkarsh; Ghosh, Tanmay; Aabdin, Zainul; Koneti, Siddardha; Xu, XiuMei; Holsteyns, Frank; Mirsaidov, Utkur Dynamics of thin precursor film in wetting of nanopatterned surfaces Journal Article PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 118 (38), 2021, ISSN: 0027-8424. @article{ISI:000704002000016, title = {Dynamics of thin precursor film in wetting of nanopatterned surfaces}, author = {Utkarsh Anand and Tanmay Ghosh and Zainul Aabdin and Siddardha Koneti and XiuMei Xu and Frank Holsteyns and Utkur Mirsaidov}, doi = {10.1073/pnas.2108074118}, times_cited = {0}, issn = {0027-8424}, year = {2021}, date = {2021-09-21}, journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, volume = {118}, number = {38}, publisher = {NATL ACAD SCIENCES}, address = {2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA}, abstract = {The spreading of a liquid droplet on flat surfaces is a well-understood phenomenon, but little is known about how liquids spread on a rough surface. When the surface roughness is of the nanoscopic length scale, the capillary forces dominate and the liquid droplet spreads by wetting the nanoscale textures that act as capillaries. Here, using a combination of advanced nanofabrication and liquidphase transmission electron microscopy, we image the wetting of a surface patterned with a dense array of nanopillars of varying heights. Our real-time, high-speed observations reveal that water wets the surface in two stages: 1) an ultrathin precursor water film forms on the surface, and then 2) the capillary action by nanopillars pulls the water, increasing the overall thickness of water film. These direct nanoscale observations capture the previously elusive precursor film, which is a critical intermediate step in wetting of rough surfaces.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The spreading of a liquid droplet on flat surfaces is a well-understood phenomenon, but little is known about how liquids spread on a rough surface. When the surface roughness is of the nanoscopic length scale, the capillary forces dominate and the liquid droplet spreads by wetting the nanoscale textures that act as capillaries. Here, using a combination of advanced nanofabrication and liquidphase transmission electron microscopy, we image the wetting of a surface patterned with a dense array of nanopillars of varying heights. Our real-time, high-speed observations reveal that water wets the surface in two stages: 1) an ultrathin precursor water film forms on the surface, and then 2) the capillary action by nanopillars pulls the water, increasing the overall thickness of water film. These direct nanoscale observations capture the previously elusive precursor film, which is a critical intermediate step in wetting of rough surfaces. |