Absence of free carriers in silicon nanocrystals grown from phosphorus- and boron-doped silicon-rich oxide and oxynitride

• Daniel Hiller,
• Julian López-Vidrier,
• Keita Nomoto,
• Michael Wahl,
• Wolfgang Bock,
• Tomáš Chlouba,
• František Trojánek,
• Sebastian Gutsch,
• Margit Zacharias,
• Dirk König,
• Petr Malý and
• Michael Kopnarski

Beilstein J. Nanotechnol. 2018, 9, 1501–1511, doi:10.3762/bjnano.9.141

• concentration of a semiconductor can be controlled via doping. Conventional impurity doping requires the incorporation of a suitable foreign atom on a lattice site and its ionization by thermal energy. Therefore, the energetic position of a dopant in the bandgap has to be close to the respective band edges. For

• Si, typical dopant ionization energies are in the range of ≈50 meV. If the size of the Si crystal approaches the exciton Bohr-radius, strong quantum confinement sets in and the valence- and conduction band ground state energies shift to lower and higher energies, respectively. As a consequence, the

• dopant ionization energies increase, which decreases exponentially the free carrier density [1]. If a doped Si-nanovolume is embedded in a matrix of lower permittivity (e.g., a dielectric), the dopant charge is not fully screened in the silicon and a Coulomb interaction with its image charge in the

Cr(VI) remediation from aqueous environment through modified-TiO₂-mediated photocatalytic reduction

• Rashmi Acharya,
• Brundabana Naik and
• Kulamani Parida

Beilstein J. Nanotechnol. 2018, 9, 1448–1470, doi:10.3762/bjnano.9.137

• core–shell nanotubes exhibited higher Cr(VI) oxyanion reduction and adsorption. The activity could be varied with concentration, pH and dopant acid [133]. Graphene-wrapped differently faceted (001 and 101) TiO2 hollow-core–shell microspheres (TGHMs) have been fabricated by Liu et al. and were applied

Theoretical study of strain-dependent optical absorption in a doped self-assembled InAs/InGaAs/GaAs/AlGaAs quantum dot

• Tarek A. Ameen,
• Hesameddin Ilatikhameneh,
• Archana Tankasala,
• Yuling Hsueh,
• James Charles,
• Jim Fonseca,
• Michael Povolotskyi,
• Jun Oh Kim,
• Sanjay Krishna,
• Monica S. Allen,
• Jeffery W. Allen,
• Rajib Rahman and
• Gerhard Klimeck

Beilstein J. Nanotechnol. 2018, 9, 1075–1084, doi:10.3762/bjnano.9.99

• electron–electron interactions in electrons bound to dopant atoms in silicon. The single-particle states of the quantum dot are obtained from atomistic tight-binding calculations in NEMO5. These single-electron and hole states are used to construct many-particle Slater determinants, of all possible

Optical orientation of nematic liquid crystal droplets via photoisomerization of an azodendrimer dopant

• Sergey A. Shvetsov,
• Alexander V. Emelyanenko,
• Natalia I. Boiko,
• Alexander S. Zolot'ko,
• Yan-Song Zhang,
• Jui-Hsiang Liu and
• Alexei R. Khokhlov

Beilstein J. Nanotechnol. 2018, 9, 870–879, doi:10.3762/bjnano.9.81

• structures. Among the variety of different materials containing azobenzene derivatives, there is special interest in host–guest systems consisting of a mesophase matrix and a small concentration (<1 wt %) of dopant. In particular, they reveal higher optical nonlinear response [14][21]. Some kinds of the

• homeotropic anchoring of the NLC film. The boundary conditions can be changed to planar and then return to homeotropic again by photoisomerization processes. The effects of NLC film orientation are very similar to the bulk mediated photoalignment [26][27], which are influenced by exchange of the dopant

• between the surface and the bulk. Recently, it was shown that NLC photo-orientation due to the azobenzene dopant photoisomerization can also occur at the interface between nematic and isotropic liquid [28]. It is known [29] that NLC microdroplets in the bulk of glycerol usually have bipolar orientational

Heavy-metal detectors based on modified ferrite nanoparticles

• Urszula Klekotka,
• Ewelina Wińska,
• Elżbieta Zambrzycka-Szelewa,
• Dariusz Satuła and
• Beata Kalska-Szostko

Beilstein J. Nanotechnol. 2018, 9, 762–770, doi:10.3762/bjnano.9.69

• features. The first one is the presence of a sextet with broadened lines, which is actually a superposition of sextets corresponding to Fe atoms at the A and B sites of the magnetite structure [35]. The broadening depends on the type of dopant atoms. In the case of Co ions, the full width at half maximum

• of the spectral lines is much smaller than in the other cases. An especially wide spectrum is observed in the case of magnetite doped by Mn atoms. The value of the average hyperfine magnetic field on the iron atoms is highest on the sample with Co dopant. The second characteristic feature is the

• presence of a doublet in the central part of the spectrum, which is connected to the superparamagnetic behavior of Fe magnetic moments in the studied samples. The relative intensity of the doubles depends on the kind of dopant. The most intensive doublet is observed for magnetite doped by Ca (more than 50

Combined pulsed laser deposition and non-contact atomic force microscopy system for studies of insulator metal oxide thin films

• Daiki Katsube,
• Hayato Yamashita,
• Satoshi Abo and
• Masayuki Abe

Beilstein J. Nanotechnol. 2018, 9, 686–692, doi:10.3762/bjnano.9.63

• -doped SrTiO3(100) (dopant level 0.05 wt %) and non-doped LaAlO3(100) for (a) and (c), respectively. Parameters used for thin-film growth of the anatase TiO2(001) were Ts = 800 °C, PO ≈ 1 × 10−4 Pa, I = 0.8 J/cm2, fp = 2 Hz. For LaAlO3(100) thin film growth, the parameters were Ts = 900 °C, PO ≈ 1 × 10−3

Mechanistic insights into plasmonic photocatalysts in utilizing visible light

• Kah Hon Leong,
• Azrina Abd Aziz,
• Lan Ching Sim,
• Pichiah Saravanan,
• Min Jang and
• Detlef Bahnemann

Beilstein J. Nanotechnol. 2018, 9, 628–648, doi:10.3762/bjnano.9.59

• , tungsten oxide (WO3–δ) nanocrystals showed intense NIR absorption with an LSPR peak at ≈900 nm [138]. The plasmonic resonance of semiconductors could be manipulated by tuning the stoichiometric composition, dopant concentration, or phase transitions [139][140]. The manipulation of the stoichiometric ratio

Temperature-tunable lasing from dye-doped chiral microdroplets encapsulated in a thin polymeric film

• Gia Petriashvili,
• Mauro Daniel Luigi Bruno,
• Maria Penelope De Santo and
• Riccardo Barberi

Beilstein J. Nanotechnol. 2018, 9, 379–383, doi:10.3762/bjnano.9.37

• film. Here, we report on the possibility to tune the laser emission as a function of temperature. Using a chiral dopant with temperature dependent solubility, the emitted laser wavelength can be tuned in a range of 40 nm by a temperature variation of 18 °C. The proposed device can have applications in

• systems [6][7][8]. Further, since the PBG spectral position can be shifted, also the laser emission wavelength can be tuned by using external factors as the temperature variations. CLCs are often mixtures of nematic liquid crystal and chiral dopant. A chiral dopant with temperature dependent solubility

• that the laser emission tuning can be obtained preparing the CLC mixture by using a chiral dopant with temperature-dependent solubility. For both emulsion and thin film form, the laser emission wavelength can be tuned. In particular, laser emission from the thin film is tuned over a range of about 40

Dopant-stimulated growth of GaN nanotube-like nanostructures on Si(111) by molecular beam epitaxy

• Alexey D. Bolshakov,
• Alexey M. Mozharov,
• Georgiy A. Sapunov,
• Igor V. Shtrom,
• Nickolay V. Sibirev,
• Vladimir V. Fedorov,
• Evgeniy V. Ubyivovk,
• Maria Tchernycheva,
• George E. Cirlin and
• Ivan S. Mukhin

Beilstein J. Nanotechnol. 2018, 9, 146–154, doi:10.3762/bjnano.9.17

• the study, we introduce a new dopant-stimulated method for GaN nanotube-like nanostructure synthesis using a high-intensity Si flux. Transmission electron microscopy was used to investigate the morphological features of the GaN nanostructures. The synthesized structures have a hexagonal cross-section

• and possess high crystal quality. We propose a theoretical model of the novel nanostructure formation which includes the role of the dopant Si. Some of the Si-doped samples were studied with the photoluminescence (PL) technique. The analysis of the PL spectra shows that the highest value of donor

• demonstrated that in the presence of a sufficient Si doping flux, a radial gradient of the dopant concentration exists inside the n-GaN NW and a less doped core accompanied by thin heavily doped shell may form [28][29]. A similar NW doping effect has been obtained in the growth study of InN NWs [30]. It should

Thermo- and electro-optical properties of photonic liquid crystal fibers doped with gold nanoparticles

• Agata Siarkowska,
• Miłosz Chychłowski,
• Daniel Budaszewski,
• Bartłomiej Jankiewicz,
• Bartosz Bartosewicz and
• Tomasz R. Woliński

Beilstein J. Nanotechnol. 2017, 8, 2790–2801, doi:10.3762/bjnano.8.278

• 1.0 wt %, for direct comparison of the influence of the dopant on the properties of the PLCF. The thermo-optical effects of the liquid crystal doped with gold NPs were compared in three setups, an LC cell, a microcapillary and within the PLCF, to determine if the observed responses to external factors

• stable due to relatively weak interactions of dopant particles [14]. Up to now, NP-doped LCs have been reported mostly in LC cells. In this paper, we present the experimental results of electro- and thermo-optic properties of LC cells as well as silica glass microcapillaries (MCs) and photonic crystal

• polarizers. Similar effects were observed for both LC cells and MCs. We observed that an increase of the Au dopant in the LC lowered the N–I phase transition temperature. For lower NP concentrations (0.1 wt % and 0.3 wt %), the transition temperature remained close to 43 °C. However, a higher concentration

Impact of titanium dioxide nanoparticles on purification and contamination of nematic liquid crystals

• Dmitrii Pavlovich Shcherbinin and
• Elena A. Konshina

Beilstein J. Nanotechnol. 2017, 8, 2766–2770, doi:10.3762/bjnano.8.275

• different density, size, diffusion coefficient and adsorption/desorption rates. In such complicated systems, the proportion between different types of ions can change [24][29] and may influence the average diffusion coefficient. Moreover, the change of dopant concentration may have resulted in the variation

Enhanced photoelectrochemical water splitting performance using morphology-controlled BiVO₄ with W doping

• Xin Zhao and
• Zhong Chen

Beilstein J. Nanotechnol. 2017, 8, 2640–2647, doi:10.3762/bjnano.8.264

• . Both samples have almost the same composition, the Bi/V/W/O ratio is 1:0.88:0.03:3.45 for the 0-water sample, and Bi/V/W/O is 1:0.88:0.035:3.4 for the 1-EG sample. The stoichiometric ratio agrees with the one for BiVO4, and the dopant concentration is about 3%. Figure 3 shows the photocurrents of W

Alternating current magnetic susceptibility of a ferronematic

• Natália Tomašovičová,
• Jozef Kováč,
• Veronika Gdovinová,
• Nándor Éber,
• Tibor Tóth-Katona,
• Jan Jadżyn and
• Peter Kopčanský

Beilstein J. Nanotechnol. 2017, 8, 2515–2520, doi:10.3762/bjnano.8.251

• the phase transition temperature to a lower value of TIN ≈ 300 K. This shift in TIN is slightly larger than that obtained at the lower dopant concentration of = 10−4 [27]). Figure 3 shows the magnetization curves of neat 6CB and of the two 6CB-based ferronematics ( = 10−4 and = 2 × 10−4), measured

Substrate and Mg doping effects in GaAs nanowires

• Perumal Kannappan,
• Nabiha Ben Sedrine,
• Jennifer P. Teixeira,
• Maria R. Soares,
• Bruno P. Falcão,
• Maria R. Correia,
• Nestor Cifuentes,
• Emilson R. Viana,
• Marcus V. B. Moreira,
• Geraldo M. Ribeiro,
• Alfredo G. de Oliveira,
• Juan C. González and
• Joaquim P. Leitão

Beilstein J. Nanotechnol. 2017, 8, 2126–2138, doi:10.3762/bjnano.8.212

• research for alternatives [29][30][31][32]. Mg is another dopant impurity [25][33][34][35][36][37][38] used for p-type doping with a low diffusion coefficient, which has a solid solubility of 1 × 1019 cm−3 and a low sticking coefficient (10−2–10−5) in the substrate temperature range of 725–850 K [34]. The

Group-13 and group-15 doping of germanane

• Nicholas D. Cultrara,
• Maxx Q. Arguilla,
• Shishi Jiang,
• Chuanchuan Sun,
• Michael R. Scudder,
• R. Dominic Ross and
• Joshua E. Goldberger

Beilstein J. Nanotechnol. 2017, 8, 1642–1648, doi:10.3762/bjnano.8.164

• -terminated graphane analogue of germanium has generated interest as a potential 2D electronic material. However, the incorporation and retention of extrinsic dopant atoms in the lattice, to tune the electronic properties, remains a significant challenge. Here, we show that the group-13 element Ga and the

• used as they require a high-temperature for post annealing to heal the lattice. Due to the existence of a large number of closely related layered Zintl phases with group-13 and group-15 elements that are structurally similar to CaGe2 dopant elements can be partially substituted into the germanium

• begin to oxidize after 24 to 96 hours in ambient atmosphere. In both cases, the incorporation of more dopant produced lower sheet resistances in H2O-containing ambient atmosphere, while only the gallium-doped samples continue to show dopant activation under vacuum and H2O-free conditions. Results and

Charge transfer from and to manganese phthalocyanine: bulk materials and interfaces

• Florian Rückerl,
• Daniel Waas,
• Bernd Büchner,
• Martin Knupfer,
• Dietrich R. T. Zahn,
• Francisc Haidu,
• Torsten Hahn and
• Jens Kortus

Beilstein J. Nanotechnol. 2017, 8, 1601–1615, doi:10.3762/bjnano.8.160

• -transfer crystals with appropriate partners [25][26]. Further, it has also been used as dopant material for organic electronic devices [27][28][29]. More recently, F6TCNNQ has been introduced into organic devices with advantages such as an even higher electron affinity and a larger molecular mass, which

Oxidative chemical vapor deposition of polyaniline thin films

• Yuriy Y. Smolin,
• Masoud Soroush and
• Kenneth K. S. Lau

Beilstein J. Nanotechnol. 2017, 8, 1266–1276, doi:10.3762/bjnano.8.128

• removing residual oxidant, short-chain oligomers, and unreacted monomer [17]. For example, Nejati et al. [31] have shown that washing oCVD PTh films removes the oxidant dopant and soluble portions of the film, which from UV–vis analysis was composed of short chain oligomers of five repeat units or shorter

• and charged-balanced with a counterion dopant like chloride [43]. The PANI characteristic peaks are located at 3304, 3064, 1577, 1490, 1382, 1168, 821, and 516 cm−1. The 3304 and 3000–3100 cm−1 peaks are assigned to NH and CH stretching, respectively, on the aromatic ring of PANI [44][45][46]. The

• peak at 1382 cm−1, assigned to CN stretching vibration in the quinoid region, is smaller, which further confirms that the LT-BC film contains a smaller amount of quinoid groups. Previous work on oCVD PEDOT showed similar trends with a lower stage temperature yielding lower conjugation length and dopant

Characterization of ferrite nanoparticles for preparation of biocomposites

• Urszula Klekotka,
• Magdalena Rogowska,
• Dariusz Satuła and
• Beata Kalska-Szostko

Beilstein J. Nanotechnol. 2017, 8, 1257–1265, doi:10.3762/bjnano.8.127

• , Mn and Ni dopant elements calculated from Equation 1 differ from the pure magnetite crystalline grain size (Table 1). This modification/decrease is due to the change/increase of the width of the structural peaks, which is a consequence of particle composition, particle size, stress and many other

Structural properties and thermal stability of cobalt- and chromium-doped α-MnO₂ nanorods

• Romana Cerc Korošec,
• Polona Umek,
• Alexandre Gloter,
• Jana Padežnik Gomilšek and
• Peter Bukovec

Beilstein J. Nanotechnol. 2017, 8, 1032–1042, doi:10.3762/bjnano.8.104

• that the content of the dopant ions decreases with increasing reaction temperature. The oxidation of Co2+ to Co3+ during the reaction was proved by an XANES study, while EXAFS results confirm that both dopant ions substitute Mn4+ in the center of an octahedron. The K/Mn ratio in the doped samples

• that of the undoped ones. Dopant ions do not preserve the MnO2 phase at higher temperatures nor do they destabilize the cryptomelane structure. Keywords: α-MnO2; doping; EXAFS; nanorods; XANES; Introduction The wide range of physical and chemical properties of manganese dioxide (MnO2), which exists

• cryptomelane samples exhibit a higher thermal stability than undoped ones. For instance, doping with tin and cobalt shifted the reduction of α-MnO2 to Mn2O3 from 500–550 °C (undoped sample) to 850–900 °C [19][20]. This was ascribed to the incorporation of dopant ions into tunnels stabilizing the structure [19

Graphene functionalised by laser-ablated V₂O₅ for a highly sensitive NH₃ sensor

• Margus Kodu,
• Artjom Berholts,
• Tauno Kahro,
• Mati Kook,
• Peeter Ritslaid,
• Helina Seemen,
• Tea Avarmaa,
• Harry Alles and
• Raivo Jaaniso

Beilstein J. Nanotechnol. 2017, 8, 571–578, doi:10.3762/bjnano.8.61

• charged atoms on the surface. Consequently, the adsorption energy is due to van der Waals forces, and may be less or comparable to kBT (where kB is the Boltzmann constant and T the absolute temperature) for gases at room temperature. The introduction of defects and dopant atoms into graphene can

• increased charge transfer and formation of chemical bonds between the dopant and adsorbate [6][32]. Moreover, changes in the electronic structure induced by adsorption of molecules are likely to modulate the conductivity of graphene [32]. According to the Raman analysis shown in Figure 1, the PLD process

In-situ monitoring by Raman spectroscopy of the thermal doping of graphene and MoS₂ in O₂-controlled atmosphere

• Aurora Piazza,
• Filippo Giannazzo,
• Gianpiero Buscarino,
• Gabriele Fisichella,
• Antonino La Magna,
• Fabrizio Roccaforte,
• Marco Cannas,
• Franco Mario Gelardi and
• Simonpietro Agnello

Beilstein J. Nanotechnol. 2017, 8, 418–424, doi:10.3762/bjnano.8.44

• application such as thin flexible circuits and interconnecting transparent conductive electrodes for solar cells and/or touch screens [6]. Among the possible dopants for Gr, an easily accessible and promising one is oxygen. It acts as a p-type dopant and can also be activated by thermal treatments [13][14

Obtaining and doping of InAs-QD/GaAs(001) nanostructures by ion beam sputtering

• Sergei N. Chebotarev,
• Alexander S. Pashchenko,
• Leonid S. Lunin,
• Elena N. Zhivotova,
• Georgy A. Erimeev and
• Marina L. Lunina

Beilstein J. Nanotechnol. 2017, 8, 12–20, doi:10.3762/bjnano.8.2

• change the evaporation cosine law. A SnTe solid-state source was used as a dopant. This compound was already used earlier [31][32]. In our case, the usage of elementary tellurium is unacceptable because of its high vapor pressure. The vapor flux from the SnTe source was calibrated in the temperature

Ferromagnetic behaviour of ZnO: the role of grain boundaries

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

Beilstein J. Nanotechnol. 2016, 7, 1936–1947, doi:10.3762/bjnano.7.185

• constitute the additional contribution of the current review. It aims to give the comprehensive and updated view on the GB contribution to the ferromagnetic behaviour of ZnO as well as on the multilayer GB adsorption drastically increasing the overall dopant solubility in ZnO. This review is also a modest

• prepared. The Zn precursor was mixed, respectively, with Mn, Co, Ni or Fe butanoates in appropriate proportions (in order to obtain doped ZnO with dopant contents from 0.1 to 50 atom %). The mixture of liquid precursors was deposited on a substrate (aluminium polycrystalline foil or sapphire single

• state. Both these results permit us to conclude that unpaired electrons can exist in GBs and atomic configurations may exist where such electrons are coupled ferromagnetically [13]. Influence of dopant concentration on the ferromagnetic behaviour of ZnO In Figure 1b–e the data on presence or absence of

Fingerprints of a size-dependent crossover in the dimensionality of electronic conduction in Au-seeded Ge nanowires

• Maria Koleśnik-Gray,
• Gillian Collins,
• Justin D. Holmes and
• Vojislav Krstić

Beilstein J. Nanotechnol. 2016, 7, 1574–1578, doi:10.3762/bjnano.7.151

• cases exceeds the intrinsic doping level of bulk Ge (1.3 × 1013 cm−3 [22]), which indicates that the carrier-concentration is equivalent to the number density of ionized acceptor levels (surface–dopant concentration). Numerical fitting revealed Nd(R) ~ R−α with α = 3.05 ± 0.37 showing that large radius

• non-trivial Nd(R) dependence, it is instructive to graph the conductivity and mobility as a function of carrier density, as is shown in Figure 3. For low dopant densities, σNW(Nd) first increases by two orders of magnitude, and for Nd exceeding ≈1016 cm−3 it enters into a slowly varying regime (Figure

High performance Ce-doped ZnO nanorods for sunlight-driven photocatalysis

• Bilel Chouchene,
• Tahar Ben Chaabane,
• Lavinia Balan,
• Emilien Girot,
• Kevin Mozet,
• Ghouti Medjahdi and
• Raphaël Schneider

Beilstein J. Nanotechnol. 2016, 7, 1338–1349, doi:10.3762/bjnano.7.125

• ZnO rods when varying the Ce-dopant percentage from 0 to 10. The XRD patterns show sharp peaks, indicating a high degree of crystallinity. The peaks located at 2θ values of 31.7, 34.3, 36.1, 47.5, 56.5, 62.7, 67.8 and 69° are ascribed to the (100), (002), (101), (102), (110), (103), (112) and (201

• indicate that there are quite no changes in the ZnO bandgap when varying the dopant percentage in Ce, which is in good accordance with absorption results previously described and with a recent report from the literature [34]. Scanning electron microscopy (SEM) images of ZnO and ZnO:Ce particles indicate

• ability of the Ce dopant to reduce charge recombinations is promising for the efficient photodegradation of pollutants. Photocatalytic degradation of Orange II We first investigated the photocatalytic activities of Ce-doped ZnO in comparison to ZnO rods in the photodegradation of Orange II used at a 10 mg