Nanostructured TiO₂-based gas sensors with enhanced sensitivity to reducing gases

• Wojciech Maziarz,
• Anna Kusior and
• Anita Trenczek-Zajac

Beilstein J. Nanotechnol. 2016, 7, 1718–1726, doi:10.3762/bjnano.7.164

• carrier transfer occurs and formation of a charge depletion layer. The discrete SnO2 nanoparticle coating acts as an oxygen adsorber, which donates electrons and increases carrier concentration, creating a stronger n–p heterojunction. As a result, tin oxide may become the primary conductive path, which

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

• NWs are comparably lightly doped. We note that the carrier concentration in the NW depends on the surface-state density which can vary depending on the synthesis conditions [15][23][24]. Therefore, the radius dependence of the carrier concentration may vary in differently grown NWs. Since we found a

Localized surface plasmons in structures with linear Au nanoantennas on a SiO₂/Si surface

• Ilya A. Milekhin,
• Sergei A. Kuznetsov,
• Ekaterina E. Rodyakina,
• Alexander G. Milekhin,
• Alexander V. Latyshev and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2016, 7, 1519–1526, doi:10.3762/bjnano.7.145

• deal with the localized surface plasmon excitations induced by Au nanoantennas that interact with the bulk optical phonons in the SiO2 layer. Moreover, the SiO2 layer thickness governs the LSPR mode frequency in a similar manner as the free-carrier concentration specifies the plasmon frequency in ionic

Diameter-driven crossover in resistive behaviour of heavily doped self-seeded germanium nanowires

• Stephen Connaughton,
• Maria Koleśnik-Gray,
• Richard Hobbs,
• Olan Lotty,
• Justin D. Holmes and
• Vojislav Krstić

Beilstein J. Nanotechnol. 2016, 7, 1284–1288, doi:10.3762/bjnano.7.119

• density of states at the bottom of sub-bands involved (Supporting Information File 1) and thus is responsible for the peak feature: The carrier concentration increases with diameter reduction (acting to lower the resistivity), in opposition to the decreasing mobility. That is, when the mobility is

• constant, the concentration increase dominates and the resistivity reduces as the diameter is lowered. For other diameters the mobility reduction counterbalances the concentration increase leading to a resistivity augmentation with decreasing diameter. Therefore the change from mobility- to carrier

• -concentration-dominated resistivity leads to the peak-feature observed. Also, the appearance of such a peak is only expected in thin nanowires (sufficiently confined electronic system) with significant interface/surface state doping. Although the position of the peak-like feature at 14 nm is well qualitatively

Synthesis and applications of carbon nanomaterials for energy generation and storage

• Marco Notarianni,
• Jinzhang Liu,
• Kristy Vernon and
• Nunzio Motta

Beilstein J. Nanotechnol. 2016, 7, 149–196, doi:10.3762/bjnano.7.17

• areas of defects as demonstrated by TEM images (Figure 18) [111]. GO and rGO can be easily distinguished by standard optical observation [109]. rGO usually has an increased charge carrier concentration and mobility that results in improved light reflection when deposited onto a metallic substrate as

Large area scanning probe microscope in ultra-high vacuum demonstrated for electrostatic force measurements on high-voltage devices

• Urs Gysin,
• Thilo Glatzel,
• Thomas Schmölzer,
• Adolf Schöner,
• Sergey Reshanov,
• Holger Bartolf and
• Ernst Meyer

Beilstein J. Nanotechnol. 2015, 6, 2485–2497, doi:10.3762/bjnano.6.258

• and ND the doping concentrations for the p- and n-type materials, respectively. The intrinsic charge carrier concentration can be calculated to be ni = 9.65 × 10−9 cm−3 by using the temperature-corrected values (T = 300 K) for the band gap Eg = Eg,0 − 6.5 × 10−4·T2/(T + 1300) = 3.25 eV and the

A single-source precursor route to anisotropic halogen-doped zinc oxide particles as a promising candidate for new transparent conducting oxide materials

• Daniela Lehr,
• Markus R. Wagner,
• Johanna Flock,
• Julian S. Reparaz,
• Clivia M. Sotomayor Torres,
• Alexander Klaiber,
• Thomas Dekorsy and
• Sebastian Polarz

Beilstein J. Nanotechnol. 2015, 6, 2161–2172, doi:10.3762/bjnano.6.222

• noted, that the measurements show a high transparency in the visible region (≈2.7–1.7 eV). However, whether the free carrier concentration of the materials presented is here is sufficiently high, is a matter of discussion. The described blue shift can be confirmed by photoluminescence (PL) spectroscopy

Low cost, p-ZnO/n-Si, rectifying, nano heterojunction diode: Fabrication and electrical characterization

• Vinay Kabra,
• Lubna Aamir and
• M. M. Malik

Beilstein J. Nanotechnol. 2014, 5, 2216–2221, doi:10.3762/bjnano.5.230

• . Hall effect measurement The Hall effect measurement of a p-ZnO rectangular pellet with dimensions 0.8 × 0.8 × 0.1 cm3 was performed using a four-probe van der Pauw method using silver contacts, and data were averaged to ensure accuracy. The carrier concentration, Hall mobility and resistivity of p-ZnO

• values of the carrier concentration, Hall mobility and resistivity of Si substrate were found to be 2.3 × 1015 cm−3, 555 cm2/Vs, and 5 Ωcm, respectively. It is apparent that the carrier concentration, mobility and resistivity of these p-ZnO nanoparticles are sufficient for use in the fabrication of a

• heterojunction diode. Furthermore, work is in progress to achieve a carrier concentration for the p-ZnO nanoparticles on the order of 1018 cm−3. Current–voltage (I–V) characteristics Figure 2a shows the I–V characteristics of the p-ZnO/n-Si nano heterojunction diode (area: 0.25 cm2) under dark and UV

Sequence-dependent electrical response of ssDNA-decorated carbon nanotube, field-effect transistors to dopamine

• Hari Krishna Salila Vijayalal Mohan,
• Jianing An and
• Lianxi Zheng

Beilstein J. Nanotechnol. 2014, 5, 2113–2121, doi:10.3762/bjnano.5.220

• voltage (−∆Vth) [25]. The electron donation to the SWCNT reduces the charge carrier concentration inside the nanotubes resulting in the formation of static charges, which reduces the slope of the transfer curve by generation of carrier scattering (−∆gmp/gmp) [17]. Furthermore, the charge trapping ability

Photodetectors based on carbon nanotubes deposited by using a spray technique on semi-insulating gallium arsenide

• Domenico Melisi,
• Maria Angela Nitti,
• Marco Valentini,
• Antonio Valentini,
• Teresa Ligonzo,
• Giuseppe De Pascali and
• Marianna Ambrico

Beilstein J. Nanotechnol. 2014, 5, 1999–2006, doi:10.3762/bjnano.5.208

• ), custom-made transparent Mylar masks were used to better confine the CNT deposition area. SI GaAs substrates (350 ± 25 μm, resistivity 5.4·107–9.1·107 Ω·cm, Hall mobility 5692–6025 cm2·V−1·s−1, carrier concentration 1.2·107–2.1·107 cm−3), produced by Wafer Technology LTD, were used for the fabrication of

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

• zero gap semiconductor with its valence and conduction bands touching each other at the corners of the Brillouin zone in the so called Dirac points [11][12]. This implies that, neglecting the effect of thermal excitations, the intrinsic charge carrier concentration in graphene is, in principle, zero

Review of nanostructured devices for thermoelectric applications

• Giovanni Pennelli

Beilstein J. Nanotechnol. 2014, 5, 1268–1284, doi:10.3762/bjnano.5.141

• , the same for holes) depends on charge carrier concentration and mobility, and it is strictly connected with the electrical conductivity σ. The thermal conductivity of metals is principally due to ke, which is related to the electrical conductivity σ through the well-known Wiedemann–Franz law: The

Organic and inorganic–organic thin film structures by molecular layer deposition: A review

• Pia Sundberg and
• Maarit Karppinen

Beilstein J. Nanotechnol. 2014, 5, 1104–1136, doi:10.3762/bjnano.5.123

Integration of ZnO and CuO nanowires into a thermoelectric module

• Dario Zappa,
• Simone Dalola,
• Guido Faglia,
• Elisabetta Comini,
• Matteo Ferroni,
• Caterina Soldano,
• Vittorio Ferrari and
• Giorgio Sberveglieri

Beilstein J. Nanotechnol. 2014, 5, 927–936, doi:10.3762/bjnano.5.106

• enhanced by improving electrical contact resistances; moreover, an increase in carrier concentration will boost the thermoelectric performance [34]. The main limitation of this prototype is to be found in the still high electrical resistance of the material, especially ZnO, limiting both the power factor

An analytical approach to evaluate the performance of graphene and carbon nanotubes for NH₃ gas sensor applications

• Elnaz Akbari,
• Vijay K. Arora,
• Aria Enzevaee,
• Mohamad. T. Ahmadi,
• Mehdi Saeidmanesh,
• Mohsen Khaledian,
• Hediyeh Karimi and
• Rubiyah Yusof

Beilstein J. Nanotechnol. 2014, 5, 726–734, doi:10.3762/bjnano.5.85

• /graphene, the carrier concentration will change due to the variability of the current in the drain and the source, which is a measurable parameter [5][25][26][27][28][29]. The best gas sensor has a high sensitivity and is capable of sensing even one atom or molecule of gas [3][30]. Numerous recent

Analytical development and optimization of a graphene–solution interface capacitance model

• Hediyeh Karimi,
• Rasoul Rahmani,
• Reza Mashayekhi,
• Leyla Ranjbari,
• Amir H. Shirdel,
• Niloofar Haghighian,
• Parisa Movahedi,
• Moein Hadiyan and
• Razali Ismail

Beilstein J. Nanotechnol. 2014, 5, 603–609, doi:10.3762/bjnano.5.71

• reach up to 200,000 cm2/V·s with a typical carrier concentration of 2·1011 cm−2 [7][14]. Recently attempts have also been made to use graphene as a novel channel material in field effect transistors (FETs) for electronics [15]. The remarkable properties of graphene reported so far included high

• = e·∂n is the charge measured in coulombs, e is the electron charge, and n is the intrinsic carrier concentration of graphene. By substitution of the applied voltage ∂V = ∂E/e to the device we obtain In the modeling process, the density of state (DOS) and the Fermi probability function, f(E), are

• graphene monolayer, and the Fermi probability function f(E) is defined as [30] The integral of these two values with respect to E gives the carrier concentration equation as By replacing the DOS and f(E) in Equation 3, the carrier concentration in the non-parabolic region is defined as Now the quantum

Dye-sensitized Pt@TiO₂ core–shell nanostructures for the efficient photocatalytic generation of hydrogen

• Jun Fang,
• Lisha Yin,
• Shaowen Cao,
• Yusen Liao and
• Can Xue

Beilstein J. Nanotechnol. 2014, 5, 360–364, doi:10.3762/bjnano.5.41

• have to be transported through the TiO2 particles with a maximum distance of ca. 60 nm to reach the Pt surface for the reduction of protons to H2. When TiO2 is simultaneously excited by the 400 ± 10 nm light, though it is weak, the charge carrier concentration in TiO2 becomes higher, which increases

Kelvin probe force microscopy of nanocrystalline TiO₂ photoelectrodes

• Alex Henning,
• Gino Günzburger,
• Res Jöhr,
• Yossi Rosenwaks,
• Biljana Bozic-Weber,
• Catherine E. Housecroft,
• Edwin C. Constable,
• Ernst Meyer and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2013, 4, 418–428, doi:10.3762/bjnano.4.49

• (after electron donation) and a charge carrier concentration gradient between the illuminated surface and the bulk due to different diffusion coefficients for electrons and holes (photo-Dember effect). The latter effect causes a potential drop forming an electric field in the z-direction across the TiO2

A look underneath the SiO₂/4H-SiC interface after N₂O thermal treatments

• Patrick Fiorenza,
• Filippo Giannazzo,
• Lukas K. Swanson,
• Alessia Frazzetto,
• Simona Lorenti,
• Mario S. Alessandrino and
• Fabrizio Roccaforte

Beilstein J. Nanotechnol. 2013, 4, 249–254, doi:10.3762/bjnano.4.26

• incorporation of electrically active nitrogen-related donors, which compensate the p-type doping in the SiC surface region. Cross-sectional SCM measurements on SiO2/4H-SiC metal/oxide/semiconductor (MOS) devices highlighted different active carrier concentration profiles in the first 10 nm underneath the

Photoresponse from single upright-standing ZnO nanorods explored by photoconductive AFM

• Igor Beinik,
• Markus Kratzer,
• Astrid Wachauer,
• Lin Wang,
• Yuri P. Piryatinski,
• Gerhard Brauer,
• Xin Yi Chen,
• Yuk Fan Hsu,
• Aleksandra B. Djurišić and
• Christian Teichert

Beilstein J. Nanotechnol. 2013, 4, 208–217, doi:10.3762/bjnano.4.21

• indicates an increase of the charge-carrier concentration. The rectifying I–V characteristics are associated with the Schottky contact between AFM tip and ZnO NR. The Schottky barrier heights (SBHs) were estimated, using the same method as applied in [31], to be 0.22 ± 0.06 eV for the dark and 0.18 ± 0.06

Functionalization of vertically aligned carbon nanotubes

• Eloise Van Hooijdonk,
• Carla Bittencourt,
• Rony Snyders and
• Jean-François Colomer

Beilstein J. Nanotechnol. 2013, 4, 129–152, doi:10.3762/bjnano.4.14

• parallel, they observed an exponential dependence of the resistance. No significant modification of the carrier concentration and tube–tube interaction was noticed. Considering that the electronic transport is driven by the localization mechanism (i.e., a localization of the electron states at the defect

Nanostructure-directed chemical sensing: The IHSAB principle and the dynamics of acid/base-interface interaction

• James L. Gole and
• William Laminack

Beilstein J. Nanotechnol. 2013, 4, 20–31, doi:10.3762/bjnano.4.3

• electrons, decreases the conductometric resistance and increases conductance. The removal of electrons, as would occur with an acidic analyte, decreases the majority charge carrier concentration and the conductance and increases resistance. The opposite behavior will be observed for a p-type semiconductor

Functionalised zinc oxide nanowire gas sensors: Enhanced NO₂ gas sensor response by chemical modification of nanowire surfaces

• Eric R. Waclawik,
• Jin Chang,
• Andrea Ponzoni,
• Isabella Concina,
• Dario Zappa,
• Elisabetta Comini,
• Nunzio Motta,
• Guido Faglia and
• Giorgio Sberveglieri

Beilstein J. Nanotechnol. 2012, 3, 368–377, doi:10.3762/bjnano.3.43

• -functionalisation (and gas-testing) conditions. In terms of an electronic effect, THMA (and DT) binding led to an increase in free-electron carrier concentration in ZnO, reflected in the increased conductivity of the functionalised nanowire gas sensors (Table 1). In terms of gas response, there are several ways in

Simple theoretical analysis of the photoemission from quantum confined effective mass superlattices of optoelectronic materials

• Debashis De,
• Sitangshu Bhattacharya,
• S. M. Adhikari,
• A. Kumar,
• P. K. Bose and
• K. P. Ghatak

Beilstein J. Nanotechnol. 2011, 2, 339–362, doi:10.3762/bjnano.2.40

• quantized steps and shows oscillatory dependences with the increasing carrier concentration. In addition, the photoemission decreases with increasing light intensity and wavelength as well as with increasing thickness exhibiting oscillatory spikes. The strong dependence of the photoemission on the light

• thermoelectric power G can be written under the condition of carrier degeneracy [25] as Using Equation 23 and Equation 24, one obtains Therefore, we can experimentally determine LD by knowing the experimental curve of G versus carrier concentration at a fixed temperature. It is evident that the DSL for a system

• transport under such conditions. The Fermi energy is again determined by the carrier energy spectrum and the carrier concentration and therefore, these two features would determine the dependence of the EMM in degenerate materials on the degree of carrier degeneracy. In recent years, the EMM in such