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Germanium Nanowires as Sensing Devices: Modelization of Electrical Properties. NANOMATERIALS 2021; 11:nano11020507. [PMID: 33671353 PMCID: PMC8061886 DOI: 10.3390/nano11020507] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/11/2021] [Accepted: 02/13/2021] [Indexed: 02/07/2023]
Abstract
In this paper, we model the electrical properties of germanium nanowires with a particular focus on physical mechanisms of electrical molecular sensing. We use the Tibercad software to solve the drift-diffusion equations in 3D and we validate the model against experimental data, considering a p-doped nanowire with surface traps. We simulate three different types of interactions: (1) Passivation of surface traps; (2) Additional surface charges; (3) Charge transfer from molecules to nanowires. By analyzing simulated I–V characteristics, we observe that: (i) the largest change in current occurs with negative charges on the surfaces; (ii) charge transfer provides relevant current changes only for very high values of additional doping; (iii) for certain values of additional n-doping ambipolar currents could be obtained. The results of these simulations highlight the complexity of the molecular sensing mechanism in nanowires, that depends not only on the NW parameters but also on the properties of the molecules. We expect that these findings will be valuable to extend the knowledge of molecular sensing by germanium nanowires, a fundamental step to develop novel sensors based on these nanostructures.
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Pérez Ramírez L, Gallet JJ, Bournel F, Lim F, Carniato S, Rochet F, Yazyev OV, Pasquarello A, Magnano E, Bondino F. Hydrogen Bonding of Ammonia with (H,OH)-Si(001) Revealed by Experimental and Ab Initio Photoelectron Spectroscopy. J Phys Chem A 2020; 124:5378-5388. [PMID: 32491866 DOI: 10.1021/acs.jpca.0c03458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Combining experimental and ab initio core-level photoelectron spectroscopy (periodic DFT and quantum chemistry calculations), we elucidated how ammonia molecules bond to the hydroxyls of the (H,OH)-Si(001) model surface at a temperature of 130 K. Indeed, theory evaluated the magnitude and direction of the N 1s (and O 1s) chemical shifts according to the nature (acceptor or donor) of the hydrogen bond and, when confronted to experiment, showed unambiguously that the probe molecule makes one acceptor and one donor bond with a pair of hydroxyls. The consistency of our approach was proved by the fact that the identified adsorption geometries are precisely those that have the largest binding strength to the surface, as calculated by periodic DFT. Real-time core-level photoemission enabled measurement of the adsorption kinetics of H-bonded ammonia and its maximum coverage (0.37 ML) under 1.5 × 10-9 mbar. Experimental desorption free energies were compared to the magnitude of the adsorption energies provided by periodic DFT calculations. Minority species were also detected on the surface. As in the case of H-bonded ammonia, DFT core-level calculations were instrumental to attribute these minority species to datively bonded ammonia molecules, associated with isolated dangling bonds remaining on the surface, and to dissociated ammonia molecules, resulting largely from beam damage.
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Affiliation(s)
- Lucía Pérez Ramírez
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique matière et Rayonnement, UMR 7614, 4 Place Jussieu, 75005 Paris, France
| | - Jean-Jacques Gallet
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique matière et Rayonnement, UMR 7614, 4 Place Jussieu, 75005 Paris, France.,Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 4891192 Gif-sur-Yvette Cedex, France
| | - Fabrice Bournel
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique matière et Rayonnement, UMR 7614, 4 Place Jussieu, 75005 Paris, France.,Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 4891192 Gif-sur-Yvette Cedex, France
| | - Florence Lim
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique matière et Rayonnement, UMR 7614, 4 Place Jussieu, 75005 Paris, France
| | - Stéphane Carniato
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique matière et Rayonnement, UMR 7614, 4 Place Jussieu, 75005 Paris, France
| | - François Rochet
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique matière et Rayonnement, UMR 7614, 4 Place Jussieu, 75005 Paris, France
| | - Oleg V Yazyev
- Chaire de Simulation à l'Echelle Atomique (CSEA), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Alfredo Pasquarello
- Chaire de Simulation à l'Echelle Atomique (CSEA), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Elena Magnano
- IOM-CNR, Laboratorio TASC, Basovizza, 34149 Trieste, Italy.,Department of Physics, University of Johannesburg, P.O. Box 524, 2006 Auckland Park, South Africa
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de Santiago F, Trejo A, Miranda A, Salazar F, Carvajal E, Pérez LA, Cruz-Irisson M. Carbon monoxide sensing properties of B-, Al- and Ga-doped Si nanowires. NANOTECHNOLOGY 2018; 29:204001. [PMID: 29480169 DOI: 10.1088/1361-6528/aab237] [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
Silicon nanowires (SiNWs) are considered as potential chemical sensors due to their large surface-to-volume ratio and their possible integration into arrays for nanotechnological applications. Detection of harmful gases like CO has been experimentally demonstrated, however, the influence of doping on the sensing capacity of SiNWs has not yet been reported. For this work, we theoretically studied the surface adsorption of a CO molecule on hydrogen-passivated SiNWs grown along the [111] crystallographic direction and compared it with the adsorption of other molecules such as NO, and O2. Three nanowire diameters and three dopant elements (B, Al and Ga) were considered, and calculations were done within the density functional theory framework. The results indicate that CO molecules are more strongly adsorbed on the doped SiNW than on the pristine SiNW. The following trend was observed for the CO adsorption energies: E A[B-doped] > E A[Al-doped] > E A[Ga-doped] > E A[undoped], for all diameters. The electronic charge transfers between the SiNWs and the adsorbed CO were estimated by using a Voronoi population analysis. The CO adsorbed onto the undoped SiNWs has an electron-acceptor character, while the CO adsorbed onto the B-, Al-, and Ga-doped SiNWs exhibits an electron-donor character. Comparing these results with the ones obtained for the NO and O2 adsorption, the larger CO adsorption energy on B-doped SiNWs indicates their good selectivity towards CO. These results suggest that SiNW-based sensors of toxic gases could represent a clear and advantageous application of nanotechnology in the improvement of human quality of life.
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Affiliation(s)
- F de Santiago
- Instituto Politécnico Nacional, ESIME-Culhuacán, Av. Santa Ana 1000, C.P. 04430, Ciudad de México, México
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Band-gap engineering of halogenated silicon nanowires through molecular doping. J Mol Model 2017; 23:314. [PMID: 29035419 DOI: 10.1007/s00894-017-3484-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 09/25/2017] [Indexed: 10/18/2022]
Abstract
In this work, we address the effects of molecular doping on the electronic properties of fluorinated and chlorinated silicon nanowires (SiNWs), in comparison with those corresponding to hydrogen-passivated SiNWs. Adsorption of n-type dopant molecules on hydrogenated and halogenated SiNWs and their chemisorption energies, formation energies, and electronic band gap are studied by using density functional theory calculations. The results show that there are considerable charge transfers and strong covalent interactions between the dopant molecules and the SiNWs. Moreover, the results show that the energy band gap of SiNWs changes due to chemical surface doping and it can be further tuned by surface passivation. We conclude that a molecular based ex-situ doping, where molecules are adsorbed on the surface of the SiNW, can be an alternative path to conventional doping. Graphical abstract Molecular doping of halogenated silicon nanowires.
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Abstract
The structural stability and electronic properties of the adsorption characteristics of several toxic gas molecules (NH3, SO2 and NO2) on a germanene monolayer were investigated using density functional theory (DFT) based on an ab initio method.
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Affiliation(s)
- Sanjeev K. Gupta
- Computational Materials and Nanoscience Group
- Department of Physics
- St. Xavier's College
- Ahmedabad 380009
- India
| | - Deobrat Singh
- Advanced Material Lab
- Department of Applied Physics
- S.V. National Institute of Technology
- Surat 395 007
- India
| | - Kaptansinh Rajput
- Advanced Material Lab
- Department of Applied Physics
- S.V. National Institute of Technology
- Surat 395 007
- India
| | - Yogesh Sonvane
- Advanced Material Lab
- Department of Applied Physics
- S.V. National Institute of Technology
- Surat 395 007
- India
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Wheeler LM, Neale NR, Chen T, Kortshagen UR. Hypervalent surface interactions for colloidal stability and doping of silicon nanocrystals. Nat Commun 2014; 4:2197. [PMID: 23893292 PMCID: PMC3731669 DOI: 10.1038/ncomms3197] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 06/25/2013] [Indexed: 01/29/2023] Open
Abstract
Colloidal semiconductor nanocrystals have attracted attention for cost-effective, solution-based deposition of quantum-confined thin films for optoelectronics. However, two significant challenges must be addressed before practical nanocrystal-based devices can be realized. The first is coping with the ligands that terminate the nanocrystal surfaces. Though ligands provide the colloidal stability needed to cast thin films from solution, these ligands dramatically hinder charge carrier transport in the resulting film. Second, after a conductive film is achieved, doping has proven difficult for further control of the optoelectronic properties of the film. Here we report the ability to confront both of these challenges by exploiting the ability of silicon to engage in hypervalent interactions with hard donor molecules. For the first time, we demonstrate the significant potential of applying the interaction to the nanocrystal surface. In this study, hypervalent interactions are shown to provide colloidal stability as well as doping of silicon nanocrystals.
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Affiliation(s)
- Lance M Wheeler
- Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, Minnesota 55455, USA
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Hazut O, Agarwala A, Amit I, Subramani T, Zaidiner S, Rosenwaks Y, Yerushalmi R. Contact doping of silicon wafers and nanostructures with phosphine oxide monolayers. ACS NANO 2012; 6:10311-10318. [PMID: 23083376 DOI: 10.1021/nn304199w] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Contact doping method for the controlled surface doping of silicon wafers and nanometer scale structures is presented. The method, monolayer contact doping (MLCD), utilizes the formation of a dopant-containing monolayer on a donor substrate that is brought to contact and annealed with the interface or structure intended for doping. A unique feature of the MLCD method is that the monolayer used for doping is formed on a separate substrate (termed donor substrate), which is distinct from the interface intended for doping (termed acceptor substrate). The doping process is controlled by anneal conditions, details of the interface, and molecular precursor used for the formation of the dopant-containing monolayer. The MLCD process does not involve formation and removal of SiO(2) capping layer, allowing utilization of surface chemistry details for tuning and simplifying the doping process. Surface contact doping of intrinsic Si wafers (i-Si) and intrinsic silicon nanowires (i-SiNWs) is demonstrated and characterized. Nanowire devices were formed using the i-SiNW channel and contact doped using the MLCD process, yielding highly doped SiNWs. Kelvin probe force microscopy (KPFM) was used to measure the longitudinal dopant distribution of the SiNWs and demonstrated highly uniform distribution in comparison with in situ doped wires. The MLCD process was studied for i-Si substrates with native oxide and H-terminated surface for three types of phosphorus-containing molecules. Sheet resistance measurements reveal the dependency of the doping process on the details of the surface chemistry used and relation to the different chemical environments of the P═O group. Characterization of the thermal decomposition of several monolayer types formed on SiO(2) nanoparticles (NPs) using TGA and XPS provides insight regarding the role of phosphorus surface chemistry at the SiO(2) interface in the overall MLCD process. The new MLCD process presented here for controlled surface doping provides a simple yet highly versatile means for achieving postgrowth doping of nanometer scale structures and interfaces.
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Affiliation(s)
- Ori Hazut
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram Jerusalem, 91904 Israel
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Miranda Á, Cartoixà X, Canadell E, Rurali R. NH3 molecular doping of silicon nanowires grown along the [112], [110], [001], and [111] orientations. NANOSCALE RESEARCH LETTERS 2012; 7:308. [PMID: 22709657 PMCID: PMC3444336 DOI: 10.1186/1556-276x-7-308] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Accepted: 04/26/2012] [Indexed: 06/01/2023]
Abstract
: The possibility that an adsorbed molecule could provide shallow electronic states that could be thermally excited has received less attention than substitutional impurities and could potentially have a high impact in the doping of silicon nanowires (SiNWs). We show that molecular-based ex-situ doping, where NH3 is adsorbed at the sidewall of the SiNW, can be an alternative path to n-type doping. By means of first-principle electronic structure calculations, we show that NH3 is a shallow donor regardless of the growth orientation of the SiNWs. Also, we discuss quantum confinement and its relation with the depth of the NH3 doping state, showing that the widening of the bandgap makes the molecular donor level deeper, thus more difficult to activate.
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Affiliation(s)
- Álvaro Miranda
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de Bellaterra, BellaterraBarcelona, 08193, Spain
- Instituto Politécnico Nacional, ESIME-Culhuacan, Av. Santa Ana 1000, México D.F., 04430, México
| | - Xavier Cartoixà
- Departament d’Enginyeria Electrònica, Universitat Autònoma de Barcelona, Campus de Bellaterra, Bellaterra, Barcelona, 08193, Spain
| | - Enric Canadell
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de Bellaterra, BellaterraBarcelona, 08193, Spain
| | - Riccardo Rurali
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de Bellaterra, BellaterraBarcelona, 08193, Spain
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