Electronic and electrochemical doping of graphene by surface adsorbates

• Hugo Pinto and
• Alexander Markevich

Beilstein J. Nanotechnol. 2014, 5, 1842–1848, doi:10.3762/bjnano.5.195

• atomic and molecular dopants. Review Mechanisms of doping Charge carriers, either electrons or holes, can be induced in graphene by the application of an electric field or by chemical doping. The electric field effect doping is usually performed in graphene-based field effect transistors (FET), in which

• , Figure 1b, act as donors and dope graphene n-type. Although surface transfer doping is an effective method to control the concentration of charge carriers in graphene the ionized dopants can act as an additional source of scattering for charge carriers and reduce their mobility. The electrochemical

• case the reaction or diffusion rates are slower than the rate of change of gate voltage electrochemical doping can lead to hysteresis effects which are often observed in graphene-based FET devices [21][22][23][24]. Electronic dopants The ability to dope graphene either n- or p-type has been

Silicon and germanium nanocrystals: properties and characterization

• Ivana Capan,
• Alexandra Carvalho and
• José Coutinho

Beilstein J. Nanotechnol. 2014, 5, 1787–1794, doi:10.3762/bjnano.5.189

• each other, and one-particle calculations actually give accurate values for the excitonic gap(s). III.2.2 Doping of Si nanocrystals: The deliberate introduction of dopants into materials lies at the heart of microelectronics. A prototypical example is the replacement of a few lattice sites in a billion

• applications of Si NCs rely on the possibility to tune their electronic states by exploring surface effects, the fact is that this is only possible in ultra-small NCs in which effective electrical doping, which leads to a spontaneous ionization of dopants at room-temperature, is yet to be demonstrated

• . Notwithstanding, the introduction of dopants in Si NCs has been unequivocally demonstrated, for instance by monitoring the 31P hyperfine splitting of the phosphorous donor state during electron paramagnetic resonance experiments [56], or from photoluminescent transitions of bound excitons to boron [57]. In small

Numerical investigation of the effect of substrate surface roughness on the performance of zigzag graphene nanoribbon field effect transistors symmetrically doped with BN

• Majid Sanaeepur,
• Arash Yazdanpanah Goharrizi and
• Mohammad Javad Sharifi

Beilstein J. Nanotechnol. 2014, 5, 1569–1574, doi:10.3762/bjnano.5.168

• tight-binding Hamiltonian. Because of the statistical nature of SR an ensemble average is taken over a large number of devices to obtain averaged device characteristics. Model and Methods The sp2 hybridization of carbon atoms in the GNR lattice is preserved in the presence of B or N dopants [34

• of Figure 2a shows that by increasing the roughness amplitude from 100 to 350 pm, the BN-doping induced transport gap decreases from 1.19 to 0.99 eV due to decreased average hopping between edge atoms of ZGNR and BN dopants. The average transmission of a 10 nm length 4h-2BN-ZGNR with 200 pm SR

• , ZGNRFETs can meet the required on/off-current ratio for future digital electronics. Top view of a 5h-2BN-ZGNR (left panel) and the same GNR with surface roughness (right panel). The blue circles represent carbon atoms while boron and nitrogen dopants are shown in green and red, respectively. (a) Averaged

Effects of palladium on the optical and hydrogen sensing characteristics of Pd-doped ZnO nanoparticles

• Anh-Thu Thi Do,
• Hong Thai Giang,
• Thu Thi Do,
• Ngan Quang Pham and
• Giang Truong Ho

Beilstein J. Nanotechnol. 2014, 5, 1261–1267, doi:10.3762/bjnano.5.140

• ], compatibility with other nanodevices, and are potentially the best gas sensors. Oxides cannot easily distinguish between different types of gases, but the addition of certain noble metals as dopants can promote the gas-sensing performance [9][10][11]. Noble metal dopants in ZnO can modify the optical and

Sublattice asymmetry of impurity doping in graphene: A review

• James A. Lawlor and
• Mauro S. Ferreira

Beilstein J. Nanotechnol. 2014, 5, 1210–1217, doi:10.3762/bjnano.5.133

• graphene, with a focus on substitutional nitrogen dopants. It is well known that one current limitation of graphene in regards to its use in electronics is that in its ordinary state it exhibits no band gap. By doping one of its two sublattices preferentially it is possible to not only open such a gap

• semiconductor technology, which is characterised by a current on/off ratio of roughly 104–107 and a band gap of at least 340 meV whilst maintaining high carrier mobility [5][13][14]. Alteration of the crystal structure through the introduction of foreign dopants is one of the more realistic avenues of approach

• in realising this goal. Atomic dopants like boron (B) or nitrogen (N) are a similar size to carbon and can be introduced easily in a variety of graphene growth processes, typically replacing carbon sites and forming substitutional impurities in the lattice, positively (p-) and negatively (n-) doping

Highly NO₂ sensitive caesium doped graphene oxide conductometric sensors

• Carlo Piloto,
• Marco Notarianni,
• Mahnaz Shafiei,
• Elena Taran,
• Dilini Galpaya,
• Cheng Yan and
• Nunzio Motta

Beilstein J. Nanotechnol. 2014, 5, 1073–1081, doi:10.3762/bjnano.5.120

• and environmental monitoring [12]. Theoretical [13][14] and experimental [15][16][17][18][19] studies have revealed that functionalization of graphene can improve significantly its gas sensing performance [20]. The presence of dopants or defects in the graphene lattice can increase the adsorption

• of oxygen groups. However, the sensor shows very long recovery, making GO-Cs a good candidate for applications requiring high sensitivities, but not fast response. Future works will focus on investigating the effect of different species and concentration of dopants on improving the selectivity

Methods for rapid frequency-domain characterization of leakage currents in silicon nanowire-based field-effect transistors

• Tomi Roinila,
• Xiao Yu,
• Jarmo Verho,
• Tie Li,
• Pasi Kallio,
• Matti Vilkko,
• Anran Gao and
• Yuelin Wang

Beilstein J. Nanotechnol. 2014, 5, 964–972, doi:10.3762/bjnano.5.110

• drain, respectively. A scanning electron microscope (SEM) image of the device is shown in Figure 5. The source and drain regions are heavily doped with boron, while the nanowire channel has a low-doping concentration of phosphorous. The contacts were doped by different dopants in order to form an off

Resonance of graphene nanoribbons doped with nitrogen and boron: a molecular dynamics study

• Ye Wei,
• Haifei Zhan,
• Kang Xia,
• Wendong Zhang,
• Shengbo Sang and
• Yuantong Gu

Beilstein J. Nanotechnol. 2014, 5, 717–725, doi:10.3762/bjnano.5.84

• discussed. A systematic study of the vibrational properties of graphene doped with nitrogen and boron is performed by means of a molecular dynamics simulation. The influence from different density or species of dopants has been assessed. It is found that the impacts on the quality factor, Q, resulting from

• different densities of dopants vary greatly, while the influence on the resonance frequency is insignificant. The reduction of the resonance frequency caused by doping with boron only is larger than the reduction caused by doping with both boron and nitrogen. This study gives a fundamental understanding of

• the resonance of graphene with different dopants, which may benefit their application as resonators. Keywords: dopant; graphene; molecular dynamics simulation; natural frequency; quality factor; resonance; Introduction Graphene has drawn intensive interest since its discovery in 2005 [1]. It has

Towards precise defect control in layered oxide structures by using oxide molecular beam epitaxy

• Federico Baiutti,
• Georg Christiani and
• Gennady Logvenov

Beilstein J. Nanotechnol. 2014, 5, 596–602, doi:10.3762/bjnano.5.70

• sequence of the atomic layers. In semiconductors MBE, the ALL-MBE method is used to deposit so called “delta doped” structures [18], where the dopants are confined to a single atomic plane. Extending this approach to the field of oxide MBE, one can do “single atomic layer engineering”, precisely defining

Tensile properties of a boron/nitrogen-doped carbon nanotube–graphene hybrid structure

• Kang Xia,
• Haifei Zhan,
• Ye Wei and
• Yuantong Gu

Beilstein J. Nanotechnol. 2014, 5, 329–336, doi:10.3762/bjnano.5.37

• with different dopants. It is found that with the presence of dopants, the hybrid structures usually exhibit lower yield strength, Young’s modulus, and earlier yielding compared to that of a pristine hybrid structure. For dopant concentrations below 2.5% no significant reduction of Young’s modulus or

• impact of dopant atoms on the mechanical properties of graphene. Huge efforts are still lying ahead especially for the newly synthesized CNT–graphene hybrid structure. Therefore, in this work, we will examine the impact of different densities and species of dopants on the tensile properties of the GNHS

• . The emphasis will be placed on Young’s modulus, E, yield strength, YS, and yield strain, YP. Computational details In order to acquire the influence of the dopants on the mechanical properties of GNHSs, the large-scale atomic/molecular massively parallel simulator (LAMMPS) [17] is utilized to carry

En route to controlled catalytic CVD synthesis of densely packed and vertically aligned nitrogen-doped carbon nanotube arrays

• Slawomir Boncel,
• Sebastian W. Pattinson,
• Valérie Geiser,
• Milo S. P. Shaffer and
• Krzysztof K. K. Koziol

Beilstein J. Nanotechnol. 2014, 5, 219–233, doi:10.3762/bjnano.5.24

• ] atoms has been frequently used to enhance or tune their physicochemical properties. Among the elemental dopants, nitrogen emerges as of particular interest in electronics since N-CNTs should be characterized by a higher electrical conductivity (n-doping). Consequently, the significance of N-CNTs in a

Ferromagnetic behaviour of Fe-doped ZnO nanograined films

• Boris B. Straumal,
• Svetlana G. Protasova,
• Andrei A. Mazilkin,
• Thomas Tietze,
• Eberhard Goering,
• Gisela Schütz,
• Petr B. Straumal and
• Brigitte Baretzky

Beilstein J. Nanotechnol. 2013, 4, 361–369, doi:10.3762/bjnano.4.42

• cobalt demonstrates only one oxidation state Co3+ whereas manganese can possess several oxidation states, namely +2, +3 and +4 [17][18]. Together with cobalt and manganese, iron is one of the most important dopants in ZnO. Similar to manganese, iron has different oxidation states (Fe2+ and Fe3+). This

• solubility of Fe-doped ZnO are now in progress; they give comparable results and will be published elsewhere. Simple calculations performed in [4][5] showed that the drastic increase of the total solubility of Co and Mn with decreasing grain size is due to the multilayer adsorption of dopants in GBs (up to

High-resolution electrical and chemical characterization of nm-scale organic and inorganic devices

• Pierre Eyben

Beilstein J. Nanotechnol. 2013, 4, 318–319, doi:10.3762/bjnano.4.35

• , threading dislocations, and microtwins that affect the diffusion of dopants and the material mobility (due to scattering). When growth is performed in narrow trenches, dislocations are trapped within the confined volume (aspect-ratio trapping) and, theoretically, defect-free layers can be obtained. However

Influence of diffusion on space-charge-limited current measurements in organic semiconductors

• Thomas Kirchartz

Beilstein J. Nanotechnol. 2013, 4, 180–188, doi:10.3762/bjnano.4.18

• will focus on acceptor-like traps in electron-only devices, i.e., situations where the traps are negatively charged when below the Fermi level. These negative charges will behave like p-type dopants and create a barrier for electrons. The electrons first have to diffuse over the barrier created by the

• an electron. The rationale of using acceptor-like defects is that many organic semiconductors are known to be p-type, i.e., to have acceptor like defects, and to show improved transport after compensation of the p-type dopants with n-type dopants [8][23][26][37][38]. Because organic semiconductors

Diamond nanophotonics

• Katja Beha,
• Helmut Fedder,
• Marco Wolfer,
• Merle C. Becker,
• Petr Siyushev,
• Mohammad Jamali,
• Anton Batalov,
• Christopher Hinz,
• Jakob Hees,
• Lutz Kirste,
• Harald Obloh,
• Etienne Gheeraert,
• Boris Naydenov,
• Ingmar Jakobi,
• Florian Dolde,
• Sébastien Pezzagna,
• Daniel Twittchen,
• Matthew Markham,
• Daniel Dregely,
• Harald Giessen,
• Jan Meijer,
• Fedor Jelezko,
• Christoph E. Nebel,
• Rudolf Bratschitsch,
• Alfred Leitenstorfer and
• Jörg Wrachtrup

Beilstein J. Nanotechnol. 2012, 3, 895–908, doi:10.3762/bjnano.3.100

• small reaction volume is that neither the reactor base plate nor the quartz walls of the surrounding bell jar is touched by the plasma. Major contaminations from the reactor walls were therefore avoided. Gaseous nickel and tungsten precursors - The controlled and targeted addition of dopants during

The memory effect of nanoscale memristors investigated by conducting scanning probe microscopy methods

• César Moreno,
• Carmen Munuera,
• Xavier Obradors and
• Carmen Ocal

Beilstein J. Nanotechnol. 2012, 3, 722–730, doi:10.3762/bjnano.3.82

• thickness of the film, RON and ROFF correspond to the resistance of the memristor for completely uniformly doped or undoped cases, respectively, and µ is the drift velocity of the dopants under an electric field E across the doped region in the presence of a current I(t). The switching characteristic

• –sample contact is a factor of ~20 larger than that in region of the film closer to the substrate interface [6]. The influence of a nonuniform electric field significantly suppresses the drift of the dopants. Nonlinear dopant drift can be taken into account in the memristor simulation I–V curve by

Synthesis and electrical characterization of intrinsic and in situ doped Si nanowires using a novel precursor

• Wolfgang Molnar,
• Alois Lugstein,
• Tomasz Wojcik,
• Peter Pongratz,
• Norbert Auner,
• Christian Bauch and
• Emmerich Bertagnolli

Beilstein J. Nanotechnol. 2012, 3, 564–569, doi:10.3762/bjnano.3.65

• adding HCl to the growth atmosphere [18]. For such VLS grown NW dopants can be introduced either through particular catalyst particles, such as In [19], Al [20] or Ga [21], which become partly incorporated into the NW during growth and thus work as p-type dopants themselves, or by adding a small amount

• . Such epitaxial NWs grow preferentially along the [112] direction, like their B-doped counterparts. The NWs themselves are rod-like, exhibit good crystallinity, and feature no observable defects or stacking faults. To test the activation of the dopants in the NWs, electrical characterization was