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Kolasinski KW. Metal-Assisted Catalytic Etching (MACE) for Nanofabrication of Semiconductor Powders. MICROMACHINES 2021; 12:776. [PMID: 34209231 PMCID: PMC8304928 DOI: 10.3390/mi12070776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 06/28/2021] [Accepted: 06/29/2021] [Indexed: 12/31/2022]
Abstract
Electroless etching of semiconductors has been elevated to an advanced micromachining process by the addition of a structured metal catalyst. Patterning of the catalyst by lithographic techniques facilitated the patterning of crystalline and polycrystalline wafer substrates. Galvanic deposition of metals on semiconductors has a natural tendency to produce nanoparticles rather than flat uniform films. This characteristic makes possible the etching of wafers and particles with arbitrary shape and size. While it has been widely recognized that spontaneous deposition of metal nanoparticles can be used in connection with etching to porosify wafers, it is also possible to produced nanostructured powders. Metal-assisted catalytic etching (MACE) can be controlled to produce (1) etch track pores with shapes and sizes closely related to the shape and size of the metal nanoparticle, (2) hierarchically porosified substrates exhibiting combinations of large etch track pores and mesopores, and (3) nanowires with either solid or mesoporous cores. This review discussed the mechanisms of porosification, processing advances, and the properties of the etch product with special emphasis on the etching of silicon powders.
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Affiliation(s)
- Kurt W Kolasinski
- Department of Chemistry, West Chester University, West Chester, PA 19383, USA
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Schönekerl S, Acker J. The Role of the Molecular Hydrogen Formation in the Process of Metal-Ion Reduction on Multicrystalline Silicon in a Hydrofluoric Acid Matrix. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:982. [PMID: 33920331 PMCID: PMC8069279 DOI: 10.3390/nano11040982] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/08/2021] [Accepted: 04/09/2021] [Indexed: 01/20/2023]
Abstract
Metal deposition on silicon in hydrofluoric acid (HF) solutions is a well-established process for the surface patterning of silicon. The reactions behind this process, especially the formation or the absence of molecular hydrogen (H2), are controversially discussed in the literature. In this study, several batch experiments with Ag+, Cu2+, AuCl4- and PtCl62- in HF matrix and multicrystalline silicon were performed. The stoichiometric amounts of the metal depositions, the silicon dissolution and the molecular hydrogen formation were determined analytically. Based on these data and theoretical considerations of the valence transfer, four reasons for the formation of H2 could be identified. First, H2 is generated in a consecutive reaction after a monovalent hole transfer (h+) to a Si-Si bond. Second, H2 is produced due to a monovalent hole transfer to the Si-H bonds. Third, H2 occurs if Si-Si back bonds of the hydrogen-terminated silicon are attacked by Cu2+ reduction resulting in the intermediate species HSiF3, which is further degraded to H2 and SiF62-. The fourth H2-forming reaction reduces oxonium ions (H3O+) on the silver/, copper/ and gold/silicon contacts via monovalent hole transfer to silicon. In the case of (cumulative) even-numbered valence transfers to silicon, no H2 is produced. The formation of H2 also fails to appear if the equilibrium potential of the 2H3O+/H2 half-cell does not reach the energetic level of the valence bands of the bulk or hydrogen-terminated silicon. Non-hydrogen-forming reactions in silver, copper and gold deposition always occur with at least one H2-forming process. The PtCl62- reduction to Pt proceeds exclusively via even-numbered valence transfers to silicon. This also applies to the reaction of H3O+ at the platinum/silicon contact. Consequently, no H2 is formed during platinum deposition.
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Affiliation(s)
- Stefan Schönekerl
- Department of Physical Chemistry, Faculty of Environment and Natural Sciences, Brandenburg University of Technology Cottbus-Senftenberg, Universitätsplatz 1, 01968 Senftenberg, Germany;
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Tamarov K, Kiviluoto R, Swanson JD, Unger BA, Ernst AT, Aindow M, Riikonen J, Lehto VP, Kolasinski KW. Low-Load Metal-Assisted Catalytic Etching Produces Scalable Porosity in Si Powders. ACS APPLIED MATERIALS & INTERFACES 2020; 12:48969-48981. [PMID: 33052667 DOI: 10.1021/acsami.0c13980] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The recently discovered low-load metal-assisted catalytic etching (LL-MACE) creates nanostructured Si with controllable and variable characteristics that distinguish this technique from the conventional high-load variant. LL-MACE employs 150 times less metal catalyst and produces porous Si instead of Si nanowires. In this work, we demonstrate that some of the features of LL-MACE cannot be explained by the present understanding of MACE. With mechanistic insight derived from extensive experimentation, it is demonstrated that (1) the method allows the use of not only Ag, Pd, Pt, and Au as metal catalysts but also Cu and (2) judicious combinations of process parameters such as the type of metal, Si doping levels, and etching temperatures facilitate control over yield (0.065-88%), pore size (3-100 nm), specific surface area (20-310 m2·g-1), and specific pore volume (0.05-1.05 cm3·g-1). The porous structure of the product depends on the space-charge layer, which is controlled by the Si doping and the chemical identity of the deposited metal. The porous structure was also dependent on the dynamic structure of the deposited metal. A distinctive comet-like structure of metal nanoparticles was observed after etching with Cu, Ag, Pd, and, in some cases, Pt; this structure consisted of 10-50 nm main particles surrounded by smaller (<5 nm) nanoparticles. With good scalability and precise control of structural properties, LL-MACE facilitates Si applications in photovoltaics, energy storage, biomedicine, and water purification.
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Affiliation(s)
- Konstantin Tamarov
- Department of Applied Physics, University of Eastern Finland, 70210 Kuopio, Finland
| | - Riku Kiviluoto
- Department of Applied Physics, University of Eastern Finland, 70210 Kuopio, Finland
| | - Joseph D Swanson
- Department of Chemistry, West Chester University, West Chester, Pennsylvania 19383-2115, United States
| | - Bret A Unger
- Department of Chemistry, West Chester University, West Chester, Pennsylvania 19383-2115, United States
| | - Alexis T Ernst
- Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269-3136, United States
| | - Mark Aindow
- Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269-3136, United States
| | - Joakim Riikonen
- Department of Applied Physics, University of Eastern Finland, 70210 Kuopio, Finland
| | - Vesa-Pekka Lehto
- Department of Applied Physics, University of Eastern Finland, 70210 Kuopio, Finland
| | - Kurt W Kolasinski
- Department of Chemistry, West Chester University, West Chester, Pennsylvania 19383-2115, United States
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Romano L, Kagias M, Vila-Comamala J, Jefimovs K, Tseng LT, Guzenko VA, Stampanoni M. Metal assisted chemical etching of silicon in the gas phase: a nanofabrication platform for X-ray optics. NANOSCALE HORIZONS 2020; 5:869-879. [PMID: 32100775 DOI: 10.1039/c9nh00709a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
High aspect ratio nanostructuring requires high precision pattern transfer with highly directional etching. In this work, we demonstrate the fabrication of structures with ultra-high aspect ratios (up to 10 000 : 1) in the nanoscale regime (down to 10 nm) by platinum assisted chemical etching of silicon in the gas phase. The etching gas is created by a vapour of water diluted hydrofluoric acid and a continuous air flow, which works both as an oxidizer and as a gas carrier for reactive species. The high reactivity of platinum as a catalyst and the formation of platinum silicide to improve the stability of the catalyst pattern allow a controlled etching. The method has been successfully applied to produce straight nanowires with section size in the range of 10-100 nm and length of hundreds of micrometres, and X-ray optical elements with feature sizes down to 10 nm and etching depth in the range of tens of micrometres. This work opens the possibility of a low cost etching method for stiction-sensitive nanostructures and a large range of applications where silicon high aspect ratio nanostructures and high precision of pattern transfer are required.
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Affiliation(s)
- Lucia Romano
- Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
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Tamarov K, Swanson JD, Unger BA, Kolasinski KW, Ernst AT, Aindow M, Lehto VP, Riikonen J. Controlling the Nature of Etched Si Nanostructures: High- versus Low-Load Metal-Assisted Catalytic Etching (MACE) of Si Powders. ACS APPLIED MATERIALS & INTERFACES 2020; 12:4787-4796. [PMID: 31888334 DOI: 10.1021/acsami.9b20514] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Metal-assisted catalytic etching (MACE) involving Ag deposited on Si particles has been reported as a facile method for the production of Si nanowires (Si NWs). We show that the structure of Si particles subjected to MACE changes dramatically in response to changing the loading of the Ag catalyst. The use of acetic acid as a surfactant and controlled injection of AgNO3(aq) enhanced Ag deposition. The use of acetic acid and controlled injection of H2O2 not only facilitated optimization of the etching step but also allowed us to identify a previously unobserved etching regime that we denote as low-load MACE (LL-MACE). Material produced by LL-MACE exhibits dramatically different yield and structural characteristics as compared to conventionally produced material. We demonstrate the production of Si NWs as well as mesoporous Si nanoparticles from an inexpensive metallurgical-grade Si powder. High loading of Ag (HL-MACE) generates parallel etch track pores created by the correlated motion of Ag nanoparticles. The uniform size distribution (predominantly 70-100 nm) of the Ag nanoparticles is generated dynamically during etching. The walls of these etch track pores are cleaved readily by ultrasonic agitation to form Si NWs. Low loading of Ag (LL-MACE) creates 10-50 nm Ag nanoparticles that etch in an uncorrelated (randomly directed) fashion to generate a bimodal distribution of mesoporosity peaking at ∼4 and 13-21 nm. The use of a syringe pump to deliver the oxidant (H2O2) and Ag+ is essential for increased product uniformity and yield. Different process temperatures and grades of Si produced significantly different pore size distributions. These results facilitate the production of Si NWs and mesoporous nanoparticles with high yield, low cost, and controlled properties that are suitable for applications in, e.g., lithium-ion batteries, drug delivery, as well as biomedical imaging and contrast enhancement.
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Affiliation(s)
- Konstantin Tamarov
- Department of Applied Physics , University of Eastern Finland , Kuopio FI-70211 , Finland
| | - Joseph D Swanson
- Department of Chemistry , West Chester University , West Chester , Pennsylvania 19383 , United States
| | - Bret A Unger
- Department of Chemistry , West Chester University , West Chester , Pennsylvania 19383 , United States
| | - Kurt W Kolasinski
- Department of Chemistry , West Chester University , West Chester , Pennsylvania 19383 , United States
| | - Alexis T Ernst
- Department of Materials Science and Engineering, Institute of Materials Science , University of Connecticut , Storrs , Connecticut 06269 , United States
| | - Mark Aindow
- Department of Materials Science and Engineering, Institute of Materials Science , University of Connecticut , Storrs , Connecticut 06269 , United States
| | - Vesa-Pekka Lehto
- Department of Applied Physics , University of Eastern Finland , Kuopio FI-70211 , Finland
| | - Joakim Riikonen
- Department of Applied Physics , University of Eastern Finland , Kuopio FI-70211 , Finland
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Kolasinski KW, Unger BA, Ernst AT, Aindow M. Crystallographically Determined Etching and Its Relevance to the Metal-Assisted Catalytic Etching (MACE) of Silicon Powders. Front Chem 2019; 6:651. [PMID: 30701171 PMCID: PMC6343677 DOI: 10.3389/fchem.2018.00651] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 12/13/2018] [Indexed: 02/04/2023] Open
Abstract
Metal-assisted catalytic etching (MACE) using Ag nanoparticles as catalysts and H2O2 as oxidant has been performed on single-crystal Si wafers, single-crystal electronics grade Si powders, and polycrystalline metallurgical grade Si powders. The temperature dependence of the etch kinetics has been measured over the range 5-37°C. Etching is found to proceed preferentially in a 〈001〉 direction with an activation energy of ~0.4 eV on substrates with (001), (110), and (111) orientations. A quantitative model to explain the preference for etching in the 〈001〉 direction is developed and found to be consistent with the measured activation energies. Etching of metallurgical grade powders produces particles, the surfaces of which are covered primarily with porous silicon (por-Si) in the form of interconnected ridges. Silicon nanowires (SiNW) and bundles of SiNW can be harvested from these porous particles by ultrasonic agitation. Analysis of the forces acting between the metal nanoparticle catalyst and the Si particle demonstrates that strongly attractive electrostatic and van der Waals interactions ensure that the metal nanoparticles remain in intimate contact with the Si particles throughout the etch process. These attractive forces draw the catalyst toward the interior of the particle and explain why the powder particles are etched equivalently on all the exposed faces.
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Affiliation(s)
- Kurt W Kolasinski
- Department of Chemistry, West Chester University, West Chester, PA, United States
| | - Bret A Unger
- Department of Chemistry, West Chester University, West Chester, PA, United States
| | - Alexis T Ernst
- Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT, United States
| | - Mark Aindow
- Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT, United States
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Chen X, Bi Q, Sajjad M, Wang X, Ren Y, Zhou X, Xu W, Liu Z. One-Dimensional Porous Silicon Nanowires with Large Surface Area for Fast Charge⁻Discharge Lithium-Ion Batteries. NANOMATERIALS (BASEL, SWITZERLAND) 2018; 8:E285. [PMID: 29702591 PMCID: PMC5977299 DOI: 10.3390/nano8050285] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 04/24/2018] [Accepted: 04/25/2018] [Indexed: 11/25/2022]
Abstract
In this study, one-dimensional porous silicon nanowire (1D⁻PSiNW) arrays were fabricated by one-step metal-assisted chemical etching (MACE) to etch phosphorus-doped silicon wafers. The as-prepared mesoporous 1D⁻PSiNW arrays here had especially high specific surface areas of 323.47 m²·g-1 and were applied as anodes to achieve fast charge⁻discharge performance for lithium ion batteries (LIBs). The 1D⁻PSiNWs anodes with feature size of ~7 nm exhibited reversible specific capacity of 2061.1 mAh·g-1 after 1000 cycles at a high current density of 1.5 A·g-1. Moreover, under the ultrafast charge⁻discharge current rate of 16.0 A·g-1, the 1D⁻PSiNWs anodes still maintained 586.7 mAh·g-1 capacity even after 5000 cycles. This nanoporous 1D⁻PSiNW with high surface area is a potential anode candidate for the ultrafast charge⁻discharge in LIBs with high specific capacity and superior cycling performance.
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Affiliation(s)
- Xu Chen
- Department of Physics and Astronomy, Yunnan University, Kunming 650091, Yunnan, China.
| | - Qinsong Bi
- Department of Physics and Astronomy, Yunnan University, Kunming 650091, Yunnan, China.
| | - Muhammad Sajjad
- Department of Physics and Astronomy, Yunnan University, Kunming 650091, Yunnan, China.
| | - Xu Wang
- Materials Science and Engineering Program, University of Houston, Houston, TX 77204, USA.
| | - Yang Ren
- Department of Physics and Astronomy, Yunnan University, Kunming 650091, Yunnan, China.
| | - Xiaowei Zhou
- Department of Physics and Astronomy, Yunnan University, Kunming 650091, Yunnan, China.
| | - Wen Xu
- Department of Physics and Astronomy, Yunnan University, Kunming 650091, Yunnan, China.
| | - Zhu Liu
- Department of Physics and Astronomy, Yunnan University, Kunming 650091, Yunnan, China.
- Micro and Nano-materials and Technology Key Laboratory of Yunnan Province, Kunming 650091, Yunnan, China.
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Ray SK, Katiyar AK, Raychaudhuri AK. One-dimensional Si/Ge nanowires and their heterostructures for multifunctional applications-a review. NANOTECHNOLOGY 2017; 28:092001. [PMID: 28120815 DOI: 10.1088/1361-6528/aa565c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Remarkable progress has been made in the field of one-dimensional semiconductor nanostructures for electronic and photonic devices. Group-IV semiconductors and their heterostructures have dominated the years of success in microelectronic industry. However their use in photonic devices is limited since they exhibit poor optical activity due to indirect band gap nature of Si and Ge. Reducing their dimensions below a characteristic length scale of various fundamental parameters like exciton Bohr radius, phonon mean free path, critical size of magnetic domains, exciton diffusion length etc result in the significant modification of bulk properties. In particular, light emission from Si/Ge nanowires due to quantum confinement, strain induced band structure modification and impurity doping may lead to the integration of photonic components with mature silicon CMOS technology in near future. Several promising applications based on Si and Ge nanowires have already been well established and studied, while others are now at the early demonstration stage. The control over various forms of energy and carrier transport through the unconstrained dimension makes Si and Ge nanowires a promising platform to manufacture advanced solid-state devices. This review presents the progress of the research with emphasis on their potential application of Si/Ge nanowires and their heterostructures for electronic, photonic, sensing and energy devices.
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Affiliation(s)
- Samit K Ray
- Department of Physics, Indian Institute of Technology, Kharagpur, West Bengal 721302, India
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Darwich W, Haumesser PH, Santini CC, Gaillard F. An Efficient, Versatile, and Safe Access to Supported Metallic Nanoparticles on Porous Silicon with Ionic Liquids. Int J Mol Sci 2016; 17:ijms17060876. [PMID: 27271608 PMCID: PMC4926410 DOI: 10.3390/ijms17060876] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 05/20/2016] [Accepted: 05/24/2016] [Indexed: 01/03/2023] Open
Abstract
The metallization of porous silicon (PSi) is generally realized through physical vapor deposition (PVD) or electrochemical processes using aqueous solutions. The former uses a strong vacuum and does not allow for a conformal deposition into the pores. In the latter, the water used as solvent causes oxidation of the silicon during the reduction of the salt precursors. Moreover, as PSi is hydrophobic, the metal penetration into the pores is restricted to the near-surface region. Using a solution of organometallic (OM) precursors in ionic liquid (IL), we have developed an easy and efficient way to fully metallize the pores throughout the several-µm-thick porous Si. This process affords supported metallic nanoparticles characterized by a narrow size distribution. This process is demonstrated for different metals (Pt, Pd, Cu, and Ru) and can probably be extended to other metals. Moreover, as no reducing agent is necessary (the decomposition in an argon atmosphere at 50 °C is fostered by surface silicon hydride groups borne by PSi), the safety and the cost of the process are improved.
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Affiliation(s)
- Walid Darwich
- CNRS-Université de Lyon-ESCPE Lyon, UMR 5265 C2P2, 43 Bd du 11 Novembre 1918, Villeurbanne 69616, France.
| | - Paul-Henri Haumesser
- CEA, LETI, MINATEC Campus, Grenoble 38054, France.
- Université Grenoble Alpes, Grenoble 38000, France.
| | - Catherine C Santini
- CNRS-Université de Lyon-ESCPE Lyon, UMR 5265 C2P2, 43 Bd du 11 Novembre 1918, Villeurbanne 69616, France.
| | - Frédéric Gaillard
- CEA, LETI, MINATEC Campus, Grenoble 38054, France.
- Université Grenoble Alpes, Grenoble 38000, France.
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Milazzo RG, Mio AM, D'Arrigo G, Grimaldi MG, Spinella C, Rimini E. Coalescence of silver clusters by immersion in diluted HF solution. J Chem Phys 2015; 143:024306. [PMID: 26178104 DOI: 10.1063/1.4926530] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The galvanic displacement deposition of silver on H-terminated Si (100) in the time scale of seconds is instantaneous and characterized by a cluster density of 10(11)-10(12) cm(-2). The amount of deposited Ag follows a t(1/2) dependence in agreement with a Cottrell diffusion limited mechanism. At the same time, during the deposition, the cluster density reduces by a factor 5. This behavior is in contrast with the assumption of immobile clusters. We show in the present work that coalescence and aggregation occur also in the samples immersed in the diluted hydrofluoric acid (HF) solution without the presence of Ag(+). Clusters agglomerate according to a process of dynamic coalescence, typical of colloids, followed by atomic redistribution at the contact regions with the generation of multiple internal twins and stacking-faults. The normalized size distributions in terms of r/rmean follow also the prediction of the Smoluchowski ripening mechanism. No variation of the cluster density occurs for samples immersed in pure H2O solution. The different behavior might be associated to the strong attraction of clusters to oxide-terminated Si surface in presence of water. The silver clusters are instead weakly bound to hydrophobic H-terminated Si in presence of HF. HF causes then the detachment of clusters and a random movement on the silicon surface with mobility of about 10(-13) cm(2)/s. Attractive interaction (probably van der Waals) among particles promotes coarsening.
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Affiliation(s)
- R G Milazzo
- CNR-IMM Institute for Microelectronics and Microsystems, I-95121 Catania, Italy
| | - A M Mio
- CNR-IMM Institute for Microelectronics and Microsystems, I-95121 Catania, Italy
| | - G D'Arrigo
- CNR-IMM Institute for Microelectronics and Microsystems, I-95121 Catania, Italy
| | - M G Grimaldi
- Department of Physics and Astronomy, Università di Catania, I-95123 Catania, Italy
| | - C Spinella
- CNR-IMM Institute for Microelectronics and Microsystems, I-95121 Catania, Italy
| | - E Rimini
- CNR-IMM Institute for Microelectronics and Microsystems, I-95121 Catania, Italy
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