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Znati S, Wharwood J, Tezanos KG, Li X, Mohseni PK. Metal-assisted chemical etching beyond Si: applications to III-V compounds and wide-bandgap semiconductors. NANOSCALE 2024; 16:10901-10946. [PMID: 38804075 DOI: 10.1039/d4nr00857j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Metal-assisted chemical etching (MacEtch) has emerged as a versatile technique for fabricating a variety of semiconductor nanostructures. Since early investigations in 2000, research in this field has provided a deeper understanding of the underlying mechanisms of catalytic etching processes and enabled high control over etching conditions for diverse applications. In this Review, we present an overview of recent developments in the application of MacEtch to nanomanufacturing and processing of III-V based semiconductor materials and other materials beyond Si. We highlight the key findings and developments in MacEtch as applied to GaAs, GaN, InP, GaP, InGaAs, AlGaAs, InGaN, InGaP, SiC, β-Ga2O3, and Ge material systems. We further review a series of active and passive devices enabled by MacEtch, including light-emitting diodes (LEDs), field-effect transistors (FETs), optical gratings, sensors, capacitors, photodiodes, and solar cells. By reviewing demonstrated control of morphology, optimization of etch conditions, and catalyst-material combinations, we aim to distill the current understanding of beyond-Si MacEtch mechanisms and to provide a bank of reference recipes to stimulate progress in the field.
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Affiliation(s)
- Sami Znati
- Microsystem Engineering, Rochester Institute of Technology, Rochester, NY 16423, USA.
- NanoPower Research Laboratories, Rochester Institute of Technology, Rochester, NY 14623, USA
| | - Juwon Wharwood
- NanoPower Research Laboratories, Rochester Institute of Technology, Rochester, NY 14623, USA
- Department of Electrical and Computer Engineering, Howard University, Washington, DC 20059, USA
| | - Kyle G Tezanos
- NanoPower Research Laboratories, Rochester Institute of Technology, Rochester, NY 14623, USA
- School of Materials Science and Chemistry, Rochester Institute of Technology, Rochester, NY 14623, USA
| | - Xiuling Li
- Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, Austin, TX 78758, USA
| | - Parsian K Mohseni
- Microsystem Engineering, Rochester Institute of Technology, Rochester, NY 16423, USA.
- NanoPower Research Laboratories, Rochester Institute of Technology, Rochester, NY 14623, USA
- School of Materials Science and Chemistry, Rochester Institute of Technology, Rochester, NY 14623, USA
- Department of Electrical and Microelectronic Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA
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2
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Wang Q, Zhou K, Zhao S, Yang W, Zhang H, Yan W, Huang Y, Yuan G. Metal-Assisted Chemical Etching for Anisotropic Deep Trenching of GaN Array. NANOMATERIALS 2021; 11:nano11123179. [PMID: 34947528 PMCID: PMC8704282 DOI: 10.3390/nano11123179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 11/20/2021] [Accepted: 11/21/2021] [Indexed: 12/03/2022]
Abstract
Realizing the anisotropic deep trenching of GaN without surface damage is essential for the fabrication of GaN-based devices. However, traditional dry etching technologies introduce irreversible damage to GaN and degrade the performance of the device. In this paper, we demonstrate a damage-free, rapid metal-assisted chemical etching (MacEtch) method and perform an anisotropic, deep trenching of a GaN array. Regular GaN microarrays are fabricated based on the proposed method, in which CuSO4 and HF are adopted as etchants while ultraviolet light and Ni/Ag mask are applied to catalyze the etching process of GaN, reaching an etching rate of 100 nm/min. We comprehensively explore the etching mechanism by adopting three different patterns, comparing a Ni/Ag mask with a SiN mask, and adjusting the etchant proportion. Under the catalytic role of Ni/Ag, the GaN etching rate nearby the metal mask is much faster than that of other parts, which contributes to the formation of deep trenches. Furthermore, an optimized etchant is studied to restrain the disorder accumulation of excessive Cu particles and guarantee a continuous etching result. Notably, our work presents a novel low-cost MacEtch method to achieve GaN deep etching at room temperature, which may promote the evolution of GaN-based device fabrication.
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Affiliation(s)
- Qi Wang
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China; (Q.W.); (K.Z.); (W.Y.); (H.Z.); (W.Y.)
| | - Kehong Zhou
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China; (Q.W.); (K.Z.); (W.Y.); (H.Z.); (W.Y.)
| | - Shuai Zhao
- State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wen Yang
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China; (Q.W.); (K.Z.); (W.Y.); (H.Z.); (W.Y.)
| | - Hongsheng Zhang
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China; (Q.W.); (K.Z.); (W.Y.); (H.Z.); (W.Y.)
| | - Wensheng Yan
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China; (Q.W.); (K.Z.); (W.Y.); (H.Z.); (W.Y.)
| | - Yi Huang
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China; (Q.W.); (K.Z.); (W.Y.); (H.Z.); (W.Y.)
- Correspondence: (Y.H.); (G.Y.)
| | - Guodong Yuan
- State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
- Correspondence: (Y.H.); (G.Y.)
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Srivastava RP, Khang DY. Structuring of Si into Multiple Scales by Metal-Assisted Chemical Etching. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2005932. [PMID: 34013605 DOI: 10.1002/adma.202005932] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/18/2020] [Indexed: 05/27/2023]
Abstract
Structuring Si, ranging from nanoscale to macroscale feature dimensions, is essential for many applications. Metal-assisted chemical etching (MaCE) has been developed as a simple, low-cost, and scalable method to produce structures across widely different dimensions. The process involves various parameters, such as catalyst, substrate doping type and level, crystallography, etchant formulation, and etch additives. Careful optimization of these parameters is the key to the successful fabrication of Si structures. In this review, recent additions to the MaCE process are presented after a brief introduction to the fundamental principles involved in MaCE. In particular, the bulk-scale structuring of Si by MaCE is summarized and critically discussed with application examples. Various approaches for effective mass transport schemes are introduced and discussed. Further, the fine control of etch directionality and uniformity, and the suppression of unwanted side etching are also discussed. Known application examples of Si macrostructures fabricated by MaCE, though limited thus far, are presented. There are significant opportunities for the application of macroscale Si structures in different fields, such as microfluidics, micro-total analysis systems, and microelectromechanical systems, etc. Thus more research is necessary on macroscale MaCE of Si and their applications.
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Affiliation(s)
- Ravi P Srivastava
- Soft Electronic Materials and Devices Laboratory, Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Korea
| | - Dahl-Young Khang
- Soft Electronic Materials and Devices Laboratory, Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Korea
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4
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Lova P, Soci C. Black GaAs: Gold-Assisted Chemical Etching for Light Trapping and Photon Recycling. MICROMACHINES 2020; 11:mi11060573. [PMID: 32517034 PMCID: PMC7344674 DOI: 10.3390/mi11060573] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 05/28/2020] [Accepted: 06/04/2020] [Indexed: 11/16/2022]
Abstract
Thanks to its excellent semiconductor properties, like high charge carrier mobility and absorption coefficient in the near infrared spectral region, GaAs is the material of choice for thin film photovoltaic devices. Because of its high reflectivity, surface microstructuring is a viable approach to further enhance photon absorption of GaAs and improve photovoltaic performance. To this end, metal-assisted chemical etching represents a simple, low-cost, and easy to scale-up microstructuring method, particularly when compared to dry etching methods. In this work, we show that the etched GaAs (black GaAs) has exceptional light trapping properties inducing a 120 times lower surface reflectance than that of polished GaAs and that the structured surface favors photon recycling. As a proof of principle, we investigate photon reabsorption in hybrid GaAs:poly (3-hexylthiophene) heterointerfaces.
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Affiliation(s)
- Paola Lova
- Correspondence: ; Tel.: +39-010-353-6192
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Lova P, Robbiano V, Cacialli F, Comoretto D, Soci C. Black GaAs by Metal-Assisted Chemical Etching. ACS APPLIED MATERIALS & INTERFACES 2018; 10:33434-33440. [PMID: 30191706 DOI: 10.1021/acsami.8b10370] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Large area surface microstructuring is commonly employed to suppress light reflection and enhance light absorption in silicon photovoltaic devices, photodetectors, and image sensors. To date, however, there are no simple means to control the surface roughness of III-V semiconductors by chemical processes similar to the metal-assisted chemical etching of black Si. Here, we demonstrate the anisotropic metal-assisted chemical etching of GaAs wafers exploiting the lower etching rate of the monoatomic Ga<111> and <311> planes. By studying the dependence of this process on different crystal orientations, we propose a qualitative reaction mechanism responsible for the self-limiting anisotropic etching and show that the reflectance of the roughened surface of black GaAs reduces up to ∼50 times compared to polished wafers, nearly doubling its absorption. This method provides a new, simple, and scalable way to enhance light absorption and power conversion efficiency of GaAs solar cells and photodetectors.
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Affiliation(s)
- Paola Lova
- Energy Research Institute at NTU (ERI@N) and Interdisciplinary Graduate School , Nanyang Technological University , 50 Nanyang Avenue , Singapore 639798
- School of Physical and Mathematical Sciences, Division of Physics and Applied Physics , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Valentina Robbiano
- Department of Physics and Astronomy and London Centre for Nanotechnology , University College London , London WC1E 6BT , United Kingdom
| | - Franco Cacialli
- Department of Physics and Astronomy and London Centre for Nanotechnology , University College London , London WC1E 6BT , United Kingdom
| | - Davide Comoretto
- Dipartimento di Chimica e Chimica Industriale , Università degli Studi di Genova , via Dodecaneso 31 , 16121 Genova , Italy
| | - Cesare Soci
- Energy Research Institute at NTU (ERI@N) and Interdisciplinary Graduate School , Nanyang Technological University , 50 Nanyang Avenue , Singapore 639798
- School of Physical and Mathematical Sciences, Division of Physics and Applied Physics , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
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6
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Wilhelm TS, Wang Z, Baboli MA, Yan J, Preble SF, Mohseni PK. Ordered Al xGa 1- xAs Nanopillar Arrays via Inverse Metal-Assisted Chemical Etching. ACS APPLIED MATERIALS & INTERFACES 2018; 10:27488-27497. [PMID: 30079732 DOI: 10.1021/acsami.8b08228] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The ternary III-V semiconductor compound, Al xGa1 -xAs, is an important material that serves a central role within a variety of nanoelectronic, optoelectronic, and photovoltaic devices. With all of its uses, the material itself poses a host of fabrication difficulties stemming from conventional top-down processing, including standard wet-chemical etching and reactive-ion etching (RIE). Metal-assisted chemical etching (MacEtch) techniques provide low-cost and benchtop methods that combine many of the advantages of RIE and wet-chemical etching, without being hindered by many of their disadvantages. Here, inverse-progression MacEtch (I-MacEtch) of Au-patterned Al xGa1 -xAs is demonstrated for the first time and is exploited for the generation of vertical and ordered nanopillar arrays. The etching solution employed here consists of citric acid (C6H8O7) and hydrogen peroxide (H2O2). The I-MacEtch evolution is tracked in time for Al xGa1 -xAs samples with compositions defined by x = 0.55, x = 0.60, and x = 0.70. The vertical and lateral etch rates (VER and LER, respectively) are shown to be tunable with Al fraction and temperature of the etching solution, based on modification of catalytically injected hole distributions. Control over the VER/LER ratio is demonstrated by tailoring etch conditions for single-step fabrication of ordered AlGaAs nanopillar arrays with predefined aspect ratios. Maximum VER and LER values of ∼40 nm/min and ∼105 nm/min, respectively, are measured for Al0.55Ga0.45As at a process temperature of 65 °C. The I-MacEtch nanofabrication methodology outlined in this study may be utilized for the processing of many devices, including high electron mobility transistors, distributed Bragg reflectors, lasers, light-emitting diodes, and multijunction solar cells containing AlGaAs components.
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Affiliation(s)
| | | | | | - Jian Yan
- Matrix Opto Co., Ltd., Suzhou 215614 , China
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7
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Van Toan N, Inomata N, Toda M, Ono T. Ion transport by gating voltage to nanopores produced via metal-assisted chemical etching method. NANOTECHNOLOGY 2018; 29:195301. [PMID: 29473829 DOI: 10.1088/1361-6528/aab1d3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In this work, we report a simple and low-cost way to create nanopores that can be employed for various applications in nanofluidics. Nano sized Ag particles in the range from 1 to 20 nm are formed on a silicon substrate with a de-wetting method. Then the silicon nanopores with an approximate 15 nm average diameter and 200 μm height are successfully produced by the metal-assisted chemical etching method. In addition, electrically driven ion transport in the nanopores is demonstrated for nanofluidic applications. Ion transport through the nanopores is observed and could be controlled by an application of a gating voltage to the nanopores.
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Affiliation(s)
- Nguyen Van Toan
- Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan
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8
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Asoh H, Imai R, Hashimoto H. Au-Capped GaAs Nanopillar Arrays Fabricated by Metal-Assisted Chemical Etching. NANOSCALE RESEARCH LETTERS 2017; 12:444. [PMID: 28683539 PMCID: PMC5498430 DOI: 10.1186/s11671-017-2219-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Accepted: 06/29/2017] [Indexed: 06/07/2023]
Abstract
GaAs nanopillar arrays were successfully fabricated by metal-assisted chemical etching using Au nanodot arrays. The nanodot arrays were formed on substrates by vacuum deposition through a porous alumina mask with an ordered array of openings. By using an etchant with a high acid concentration and low oxidant concentration at a relatively low temperature, the area surrounding the Au/GaAs interface could be etched selectively. Under the optimum conditions, Au-capped GaAs nanopillar arrays were formed with an ordered periodicity of 100 nm and pillar heights of 50 nm.
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Affiliation(s)
- Hidetaka Asoh
- Department of Applied Chemistry, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo, 192-0015, Japan.
| | - Ryota Imai
- Department of Applied Chemistry, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo, 192-0015, Japan
| | - Hideki Hashimoto
- Department of Applied Chemistry, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo, 192-0015, Japan
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9
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Choi K, Song Y, Ki B, Oh J. Nonlinear Etch Rate of Au-Assisted Chemical Etching of Silicon. ACS OMEGA 2017; 2:2100-2105. [PMID: 31457564 PMCID: PMC6641051 DOI: 10.1021/acsomega.7b00232] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 04/25/2017] [Indexed: 06/08/2023]
Abstract
We demonstrated time-dependent mass transport mechanisms of Au-assisted chemical etching of Si substrates. Variations in the etch rate and surface topology were correlated with catalyst features and etching duration. Nonlinear etching characteristics were associated with the formation of pinholes and whiskers. Variable rates of mass transport as a function of whisker density accounted for the nonlinear etch rates of Si. Nanopinholes on Au catalysts facilitated the vertical mass transport of reactants and byproducts, which dramatically changed the etch rate, surface topology, and porosity of Si. The suggested transport models describe the transient mass transport and the corresponding chemical reactions.
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Affiliation(s)
- Keorock Choi
- School
of Integrated Technology, Yonsei University, 85 Songdokwahak-ro, Yeonsu-gu, Incheon 21983, Republic of Korea
- Yonsei
Institute of Convergence Technology, 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, Republic of Korea
| | - Yunwon Song
- School
of Integrated Technology, Yonsei University, 85 Songdokwahak-ro, Yeonsu-gu, Incheon 21983, Republic of Korea
- Yonsei
Institute of Convergence Technology, 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, Republic of Korea
| | - Bugeun Ki
- School
of Integrated Technology, Yonsei University, 85 Songdokwahak-ro, Yeonsu-gu, Incheon 21983, Republic of Korea
- Yonsei
Institute of Convergence Technology, 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, Republic of Korea
| | - Jungwoo Oh
- School
of Integrated Technology, Yonsei University, 85 Songdokwahak-ro, Yeonsu-gu, Incheon 21983, Republic of Korea
- Yonsei
Institute of Convergence Technology, 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, Republic of Korea
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