1
|
Zhang DB, Zhao XJ, Seifert G, Tse K, Zhu J. Twist-driven separation of p-type and n-type dopants in single-crystalline nanowires. Natl Sci Rev 2019; 6:532-539. [PMID: 34691902 PMCID: PMC8291436 DOI: 10.1093/nsr/nwz014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 01/10/2019] [Accepted: 01/19/2019] [Indexed: 11/29/2022] Open
Abstract
The distribution of dopants significantly influences the properties of semiconductors, yet effective modulation and separation of p-type and n-type dopants in homogeneous materials remain challenging, especially for nanostructures. Employing a bond orbital model with supportive atomistic simulations, we show that axial twisting can substantially modulate the radial distribution of dopants in Si nanowires (NWs) such that dopants of smaller sizes than the host atom prefer atomic sites near the NW core, while dopants of larger sizes are prone to staying adjacent to the NW surface. We attribute such distinct behaviors to the twist-induced inhomogeneous shear strain in NW. With this, our investigation on codoping pairs further reveals that with proper choices of codoping pairs, e.g. B and Sb, n-type and p-type dopants can be well separated along the NW radial dimension. Our findings suggest that twisting may lead to realizations of p-n junction configuration and modulation doping in single-crystalline NWs.
Collapse
Affiliation(s)
- Dong-Bo Zhang
- College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
- Beijing Computational Science Research Center, Beijing 100193, China
| | - Xing-Ju Zhao
- Beijing Computational Science Research Center, Beijing 100193, China
| | - Gotthard Seifert
- Theoretische Chemie, Technische Universität Dresden, Dresden D-01062, Germany
| | - Kinfai Tse
- Department of Physics, the Chinese University of Hong Kong, Hong Kong, China
| | - Junyi Zhu
- Department of Physics, the Chinese University of Hong Kong, Hong Kong, China
| |
Collapse
|
2
|
Amato M, Ossicini S, Canadell E, Rurali R. Preferential Positioning, Stability, and Segregation of Dopants in Hexagonal Si Nanowires. NANO LETTERS 2019; 19:866-876. [PMID: 30608707 DOI: 10.1021/acs.nanolett.8b04083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We studied the physics of common p- and n-type dopants in hexagonal-diamond Si, a Si polymorph that can be synthesized in nanowire geometry without the need of extreme pressure conditions, by means of first-principles electronic structure calculations and compared our results with those for the well-known case of cubic-diamond nanowires. We showed that (i) as observed in recent experiments, at larger diameters (beyond the quantum confinement regime) p-type dopants prefer the hexagonal-diamond phase with respect to the cubic one as a consequence of the stronger degree of three-fold coordination of the former, while n-type dopants are at a first approximation indifferent to the polytype of the host lattice; (ii) in ultrathin nanowires, because of the lower symmetry with respect to bulk systems and the greater freedom of structural relaxation, the order is reversed and both types of dopant slightly favor substitution at cubic lattice sites; (iii) the difference in formation energies leads, particularly in thicker nanowires, to larger concentration differences in different polytypes, which can be relevant for cubic-hexagonal homojunctions; (iv) ultrasmall diameters exhibit, regardless of the crystal phase, a pronounced surface segregation tendency for p-type dopants. Overall these findings shed light on the role of crystal phase in the doping mechanism at the nanoscale and could have a great potential in view of the recent experimental works on group IV nanowires polytypes.
Collapse
Affiliation(s)
- Michele Amato
- Laboratoire de Physique des Solides (LPS) , CNRS, Université Paris-Sud, Université Paris-Saclay, Centre Scientifique d'Orsay , F91405 Orsay cedex , France
| | - Stefano Ossicini
- "Centro S3", CNR-Istituto di Nanoscienze , Via Campi 213/A , 41125 Modena , Italy
- Dipartimento di Scienze e Metodi dell'Ingegneria, Centro Interdipartimentale En&Tech , Universitá di Modena e Reggio Emilia , Via Amendola 2 Pad. Morselli , I-42100 Reggio Emilia , Italy
| | - Enric Canadell
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de Bellaterra , 08193 Bellaterra, Barcelona , Spain
| | - Riccardo Rurali
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de Bellaterra , 08193 Bellaterra, Barcelona , Spain
| |
Collapse
|
3
|
Cao H, Li X, Zhou B, Chen T, Shi T, Zheng J, Liu G, Wang Y. On-Demand Fabrication of Si/SiO 2 Nanowire Arrays by Nanosphere Lithography and Subsequent Thermal Oxidation. NANOSCALE RESEARCH LETTERS 2017; 12:105. [PMID: 28209026 PMCID: PMC5307406 DOI: 10.1186/s11671-017-1883-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 01/31/2017] [Indexed: 06/06/2023]
Abstract
We demonstrate the fabrication of the large-area arrays of vertically aligned Si/SiO2 nanowires with full tunability of the geometry of the single nanowires by the metal-assisted chemical etching technique and the following thermal oxidation process. To fabricate the geometry controllable Si/SiO2 nanowire (NW) arrays, two critical issues relating with the size control of polystyrene reduction and oxide thickness evolution are investigated. Through analyzing the morphology evolutions of polystyrene particles, we give a quantitative description on the diameter variations of polystyrene particles with the etching time of plasma etching. Based on this, pure Si NW arrays with controllable geometry are generated. Then the oxide dynamic of Si NW is analyzed by the extended Deal-Grove model. By control, the initial Si NWs and the thermal oxidation time, the well-aligned Si/SiO2 composite NW arrays with controllable geometry are obtained.
Collapse
Affiliation(s)
- Huaxiang Cao
- Key Laboratory of Material Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, 230031 People’s Republic of China
- University of Science and Technology of China, Hefei, 230026 People’s Republic of China
| | - Xinhua Li
- Key Laboratory of Material Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, 230031 People’s Republic of China
| | - Bukang Zhou
- Key Laboratory of Material Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, 230031 People’s Republic of China
- University of Science and Technology of China, Hefei, 230026 People’s Republic of China
| | - Tao Chen
- Key Laboratory of Material Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, 230031 People’s Republic of China
- University of Science and Technology of China, Hefei, 230026 People’s Republic of China
| | - Tongfei Shi
- Key Laboratory of Material Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, 230031 People’s Republic of China
| | - Jianqiang Zheng
- Key Laboratory of Material Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, 230031 People’s Republic of China
- University of Science and Technology of China, Hefei, 230026 People’s Republic of China
| | - Guangqiang Liu
- Key Laboratory of Material Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, 230031 People’s Republic of China
| | - Yuqi Wang
- Key Laboratory of Material Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, 230031 People’s Republic of China
| |
Collapse
|
4
|
Li L, Fang Y, Xu C, Zhao Y, Zang N, Jiang P, Ziegler KJ. Fabricating vertically aligned sub-20 nm Si nanowire arrays by chemical etching and thermal oxidation. NANOTECHNOLOGY 2016; 27:165303. [PMID: 26953775 DOI: 10.1088/0957-4484/27/16/165303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Silicon nanowires (SiNWs) are appealing building blocks in various applications, including photovoltaics, photonics, and sensors. Fabricating SiNW arrays with diameters <100 nm remains challenging through conventional top-down approaches. In this work, chemical etching and thermal oxidation are combined to fabricate vertically aligned, sub-20 nm SiNW arrays. Defect-free SiNWs with diameters between 95 and 200 nm are first fabricated by nanosphere (NS) lithography and chemical etching. The key aspects for defect-free SiNW fabrication are identified as: (1) achieving a high etching selectivity during NS size reduction; (2) retaining the circular NS shape with smooth sidewalls; and (3) using a directional metal deposition technique. SiNWs with identical spacing but variable diameters are demonstrated by changing the reactive ion etching power. The diameter of the SiNWs is reduced by thermal oxidation, where self-limiting oxidation is encountered after oxidizing the SiNWs at 950 °C for 1 h. A second oxidation is performed to achieve vertically aligned, sub-20 nm SiNW arrays. Si/SiO2 core/shell NWs are obtained before removing the oxidized shell. HRTEM imaging shows that the SiNWs have excellent crystallinity.
Collapse
Affiliation(s)
- Luping Li
- Department of Chemical Engineering, University of Florida, Gainesville, FL 32611, USA
| | | | | | | | | | | | | |
Collapse
|
5
|
Ryu H, Kim J, Hong KH. Atomistic study on dopant-distributions in realistically sized, highly P-doped Si nanowires. NANO LETTERS 2015; 15:450-456. [PMID: 25555203 DOI: 10.1021/nl503770z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The dependency of dopant-distributions on channel diameters in realistically sized, highly phosphorus-doped silicon nanowires is investigated with an atomistic tight-binding approach coupled to self-consistent Schrödinger-Poisson simulations. By overcoming the limit in channel sizes and doping densities of previous studies, this work examines electronic structures and electrostatics of free-standing circular silicon nanowires that are phosphorus-doped with a high density of ∼ 2 × 10(19) cm(-3) and have 12 nm-28 nm cross-sections. Results of analysis on the channel energy indicate that the uniformly distributed dopant profile would be hardly obtained when the nanowire cross-section is smaller than 20 nm. Insufficient room to screen donor ions and shallower impurity bands are the primary reasons of the nonuniform dopant-distributions in smaller nanowires. Being firmly connected to the recent experimental study (Proc. Natl. Acad. Sci. U.S.A. 2009, 106, 15254-15258), this work establishes the first theoretical framework for understanding dopant-distributions in over-10 nm highly doped silicon nanowires.
Collapse
Affiliation(s)
- Hoon Ryu
- National Institute of Supercomputing and Networking, Korea Institute of Science and Technology Information , Daejeon 305-806, Republic of Korea
| | | | | |
Collapse
|
6
|
Pi X, Ni Z, Liu Y, Ruan Z, Xu M, Yang D. Density functional theory study on boron- and phosphorus-doped hydrogen-passivated silicene. Phys Chem Chem Phys 2015; 17:4146-51. [DOI: 10.1039/c4cp05196c] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
When silicene is passivated by hydrogen, a bandgap occurs so that it becomes a semiconductor.
Collapse
Affiliation(s)
- Xiaodong Pi
- State Key Laboratory of Silicon Materials
- Department of Materials Science
- Engineering
- Zhejiang University
- Hangzhou
| | - Zhenyi Ni
- State Key Laboratory of Silicon Materials
- Department of Materials Science
- Engineering
- Zhejiang University
- Hangzhou
| | - Yong Liu
- State Key Laboratory of Silicon Materials
- Department of Materials Science
- Engineering
- Zhejiang University
- Hangzhou
| | - Zhichao Ruan
- Department of Physics
- Zhejiang University
- Hangzhou
- China
| | - Mingsheng Xu
- Department of Polymer Science and Engineering
- Hangzhou
- China
| | - Deren Yang
- State Key Laboratory of Silicon Materials
- Department of Materials Science
- Engineering
- Zhejiang University
- Hangzhou
| |
Collapse
|
7
|
Kepenekian M, Robles R, Rurali R, Lorente N. Spin transport in dangling-bond wires on doped H-passivated Si(100). NANOTECHNOLOGY 2014; 25:465703. [PMID: 25355047 DOI: 10.1088/0957-4484/25/46/465703] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
New advances in single-atom manipulation are leading to the creation of atomic structures on H-passivated Si surfaces with functionalities important for the development of atomic and molecular based technologies. We perform total-energy and electron-transport calculations to reveal the properties and understand the features of atomic wires crafted by H removal from the surface. The presence of dopants radically change the wire properties. Our calculations show that dopants have a tendency to approach the dangling-bond wires, and in these conditions, transport is enhanced and spin selective. These results have important implications in the development of atomic-scale spintronics showing that boron, and to a lesser extent phosphorous, convert the wires in high-quality spin filters.
Collapse
Affiliation(s)
- Mikaël Kepenekian
- Institut des Sciences Chimiques de Rennes UMR 6226, CNRS-Université de Rennes 1, Rennes, France. ICN2-Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona), Spain
| | | | | | | |
Collapse
|
8
|
Pennelli G, Totaro M, Piotto M, Bruschi P. Seebeck coefficient of nanowires interconnected into large area networks. NANO LETTERS 2013; 13:2592-7. [PMID: 23668777 DOI: 10.1021/nl400705b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We measured the macroscopic Seebeck coefficient of silicon nanowires (SiNWs), organized in a highly interconnected networks on large areas (order of mm(2)). The fabricated networks are very reliable with respect to random nanowire failure and are electrically and thermally equivalent to many SiNWs placed in parallel between the electrical contacts. The equivalent SiNWs have a macroscopic length of the order of millimeters and are very narrow (width smaller than 100 nm) so that they can be used to exploit thermoelectric properties at nanoscale for macroscopic electrical power generation and/or cooling. The measurement of the Seebeck coefficient S, facilitated by the macroscopic dimensions of the network, gives an insight into two questions, nanowire effective doping and carrier mobility, which are widely discussed in the literature. We found that the measured value of S is compatible with an effective doping that is higher than that of the original wafer. This higher doping is consistent with the value estimated from the measured electrical conductivity of the SiNWs with the assumption that the electron mobility inside the nanowire is equal to that of bulk silicon.
Collapse
Affiliation(s)
- Giovanni Pennelli
- Dipartimento di Ingegneria della Informazione, Università di Pisa, Via G.Caruso, I-56122 Pisa, Italy.
| | | | | | | |
Collapse
|