Effects of swift heavy ion irradiation on structural, optical and photocatalytic properties of ZnO–CuO nanocomposites prepared by carbothermal evaporation method

• Sini Kuriakose,
• D. K. Avasthi and
• Satyabrata Mohapatra

Beilstein J. Nanotechnol. 2015, 6, 928–937, doi:10.3762/bjnano.6.96

• ], biosensors [22] and photocatalysts [23][24][25]. Nanocomposites consisting of nanostructures of ZnO and other metal-oxide semiconductors are being widely studied due to their improved physicochemical properties as compared to the individual counterparts. CuO, a p-type narrow band gap semiconductor, is

• absorption spectra of the pristine and irradiated nanocomposites are shown in Figure 3a. It can be clearly seen that swift heavy ion irradiation leads to enhanced absorption of the nanocomposite in the visible region. The band gap of pristine nanocomposite and sample irradiated at fluences of 3 × 1012, 1

• × 1013, 3 × 1013 and 1 × 1014 ions/cm2 are estimated from Tauc plots (shown in Figure 3b) to be 3.23, 3.22, 3.19, 3.19 and 3.18 eV, respectively. Swift heavy ion irradiation has been found to result in a decrease in the band gap with an increase in the ion fluence. This can be attributed to doping of Cu

Transformation of hydrogen titanate nanoribbons to TiO₂ nanoribbons and the influence of the transformation strategies on the photocatalytic performance

• Melita Rutar,
• Nejc Rozman,
• Matej Pregelj,
• Carla Bittencourt,
• Romana Cerc Korošec,
• Andrijana Sever Škapin,
• Aleš Mrzel,
• Srečo D. Škapin and
• Polona Umek

Beilstein J. Nanotechnol. 2015, 6, 831–844, doi:10.3762/bjnano.6.86

• Figure 6), which is reflected in the increase of specific surface area, i.e., by a factor of about 3 compared to TO-650. As expected, an additional calcination of CH-W and MW-W caused a slight decrease in the specific surface area of CH-W+TN and MW-W+TO. Optical band-gap features The band gap of the

• precursor HTiNRs is 3.65 eV and, as expected, the transformation to TiO2 NRs resulted in a narrowing of this band gap. Table 2 summarizes the band gaps of the selected TiO2 NR samples. In the set of samples calcined in air the band gap narrowed by about 0.2 eV. A slightly more pronounced effect is observed

• for the set of samples calcined in the NH3(g)/Ar(g) flow. In this case the band gap narrowed by about 0.3 eV when the calcination temperature was increased from 400 to 650 °C. This is attributed to the increasing amount of N–Ti–O linkage [23] and is fully in line with the XPS results (Figure 7A and

Morphology control of zinc oxide films via polysaccharide-mediated, low temperature, chemical bath deposition

• Florian Waltz,
• Hans-Christoph Schwarz,
• Andreas M. Schneider,
• Stefanie Eiden and
• Peter Behrens

Beilstein J. Nanotechnol. 2015, 6, 799–808, doi:10.3762/bjnano.6.83

• material with a direct band gap of 3.37 eV and an exciton binding energy of 60 meV [19]. Although ZnO is reported to be an n-type semiconductor (most likely due to the hydrogen impurities which act as shallow donors), it is a challenging task to control its conductivity [20]. In general, in applications

• band gap (3.37 eV) (data not shown). However, the final evidence is presented by the efficient growth of ZnO on the seeded slides; in contrast, unseeded slides did not properly support the growth of ZnO. Step 2: First CBD In the absence of hyaluronic acid (HYA), highly vertically aligned ZnO nanorods

Microwave assisted synthesis and characterisation of a zinc oxide/tobacco mosaic virus hybrid material. An active hybrid semiconductor in a field-effect transistor device

• Shawn Sanctis,
• Rudolf C. Hoffmann,
• Sabine Eiben and
• Jörg J. Schneider

Beilstein J. Nanotechnol. 2015, 6, 785–791, doi:10.3762/bjnano.6.81

• defined semiconducting nanostructures in the nanometer range, deposition of ZnO nanoparticles onto the wild type TMV (wt TMV) presents itself to be an ideal choice of material combination. Zinc oxide (ZnO) is one the most widely studied, non-toxic, n-type semiconducting inorganic oxide with a direct band

• -gap of ≈3.37 eV. This enables the fabrication of functional zinc oxide based transistors [11][12]. The ability to fabricate zinc oxide based transistors from various precursor solutions, under mild basic conditions, makes it a suitable candidate to be deposited upon the TMV template [13]. We have

Statistics of work and orthogonality catastrophe in discrete level systems: an application to fullerene molecules and ultra-cold trapped Fermi gases

• Antonello Sindona,
• Michele Pisarra,
• Mario Gravina,
• Cristian Vacacela Gomez,
• Pierfrancesco Riccardi,
• Giovanni Falcone and
• Francesco Plastina

Beilstein J. Nanotechnol. 2015, 6, 755–766, doi:10.3762/bjnano.6.78

• separated by an average energy difference of about 0.2 eV. The predicted band gap value of 1.82 eV for C60 is consistent with experiments [47] and previous calculations [18]. Core ionization leads to a decrease of the band gap in of about 0.5 eV (Table 1). In order to determine the symmetry of the valence

Tm-doped TiO₂ and Tm₂Ti₂O₇ pyrochlore nanoparticles: enhancing the photocatalytic activity of rutile with a pyrochlore phase

• Desiré M. De los Santos,
• Javier Navas,
• Teresa Aguilar,
• Antonio Sánchez-Coronilla,
• Concha Fernández-Lorenzo,
• Rodrigo Alcántara,
• Jose Carlos Piñero,
• Ginesa Blanco and
• Joaquín Martín-Calleja

Beilstein J. Nanotechnol. 2015, 6, 605–616, doi:10.3762/bjnano.6.62

• catalytic properties, such as band gap energy, specific surface area, the extent of crystallinity, the structure of the material, etc. [3]. In general, a good photocatalyst should efficiently absorb photons with an energy equal to or higher than its band gap, thus generating an electron–hole pair. These

• study the optical properties of the samples and to determine the band gap energy, UV–vis spectroscopy in diffuse reflectance (DR–UV–vis) mode was used. The custom-built system was composed of: (i) an integrating sphere (Spectra Tech), (ii) a spectrometer (USB2000+, Ocean Optics), and (iii) a xenon lamp

• (Spectral Products, ASB-XE-175) as an illumination source. The Kubelka–Munk formalism and Tauc plots were used to determine the band gap energy. The Kubelka–Munk function for diffuse reflectance (R) is For a semiconductor, the plot of [f(R)·hν]n versus hν shows a linear region for n = ½ if the band gap is

Novel ZnO:Ag nanocomposites induce significant oxidative stress in human fibroblast malignant melanoma (Ht144) cells

• Syeda Arooj,
• Samina Nazir,
• Akhtar Nadhman,
• Nafees Ahmad,
• Bakhtiar Muhammad,
• Ishaq Ahmad,
• Kehkashan Mazhar and
• Rashda Abbasi

Beilstein J. Nanotechnol. 2015, 6, 570–582, doi:10.3762/bjnano.6.59

• formulations of ZnO:Ag (1, 3, 5, 10, 20 and 30% Ag) were synthesized by a simple co-precipitation method and characterized by powder X-ray diffraction, scanning electron microscopy, Rutherford back scattering and diffuse reflectance spectroscopy for their structure, morphology, composition and optical band gap

• %), ZnO:Ag (20%) and ZnO:Ag (30%) percent, respectively. Ag was found in fractions of 1.3, 2.9, 4.6, 9.7, 20.6 and 29.3% in ZnO:Ag (1%), ZnO:Ag (3%), ZnO:Ag (5%), ZnO:Ag (10%), ZnO:Ag (20%) and ZnO:Ag (30%) samples, respectively. The band-gap studies of the nanocomposites carried out through diffused

• . The band gap energies of the non-doped ZnO and Ag-doped ZnO were calculated by plotting the square of the Kubelka–Munk function [F(R)]1/2 versus the energy in eV (electron volts) [30]. A band-gap decrease was observed in all the Ag-doped ZnO to the varying extents depending upon the doped Ag (1, 3, 5

Structural, optical, opto-thermal and thermal properties of ZnS–PVA nanofluids synthesized through a radiolytic approach

• Alireza Kharazmi,
• Nastaran Faraji,
• Roslina Mat Hussin,
• Elias Saion,
• W. Mahmood Mat Yunus and
• Kasra Behzad

Beilstein J. Nanotechnol. 2015, 6, 529–536, doi:10.3762/bjnano.6.55

• past decade, the unique properties of nanometer-scale semiconductors have been investigated in the field of synthesis and characterization. Among the II–VI compounds, ZnS as a direct wide band-gap semiconductor (Eg ≈ 3.6 eV) [1], has gained more attention due to its potential applications in

• concentration in agreement with the FTIR results. The optical band gap energy of the ZnS NPs was estimated through the Tauc equation as follows [6]: where α is the absorption coefficient, hν is the photon energy of the incident light, Eg is the band gap energy, B is a constant and n depends on the type of

• transition and is 1/2, 1, 3/2 and 2 for allowed direct, allowed indirect, forbidden direct and forbidden indirect, respectively. The absorption band gap of ZnS NPs was estimated by extrapolating the linear portion of (αhν)2 as a function of hν. Consequently, the intercept of the extrapolated line with the x

Raman spectroscopy as a tool to investigate the structure and electronic properties of carbon-atom wires

• Alberto Milani,
• Matteo Tommasini,
• Valeria Russo,
• Andrea Li Bassi,
• Andrea Lucotti,
• Franco Cataldo and
• Carlo S. Casari

Beilstein J. Nanotechnol. 2015, 6, 480–491, doi:10.3762/bjnano.6.49

• . The control of the electronic properties such as the band gap and the conducting character by tuning the wire structure may open new opportunities for the realization of nanoscale cables and devices, as demonstrated by theoretical predictions [24][25] however still not experimentally demonstrated

• between the chain structure, band gap and Raman activity of the infinite chain, thus fostering the interpretation of the behavior of the existing finite length carbon chains. However, this approach also has some limitations due to non-negligible end effects. Such limitations may require the relaxation of

• electronic structure (where the band gap is modulated by the BLA, showing a transition from semiconducting (BLA ≠ 0) to metallic states (BLA = 0)), the LO phonon branch is also strongly modulated by the BLA and shows a Kohn anomaly at Γ in the case of a cumulenic chain [30][31][32][33][35]. This behavior can

Electrical properties of single CdTe nanowires

• Elena Matei,
• Camelia Florica,
• Andreea Costas,
• María Eugenia Toimil-Molares and
• Ionut Enculescu

Beilstein J. Nanotechnol. 2015, 6, 444–450, doi:10.3762/bjnano.6.45

• solar cells and its high absorption coefficient makes it extremely efficient. Figure 3 gives the optical reflection spectra for arrays of CdTe nanowires prepared at different overvoltages. The band gap of the semiconductor was determined to be 1.49 eV by employing the Kubelka–Munk function. This value

• representation for band gap determination of CdTe deposited at −500 mV. (a) The system of electrodes produced by lithography for contacting the nanowire; (b) an image of an individual nanowire contacted by FIBIM to the larger lithographically prepared electrodes. (a) Current–voltage characteristics for a CdTe

Palladium nanoparticles anchored to anatase TiO₂ for enhanced surface plasmon resonance-stimulated, visible-light-driven photocatalytic activity

• Kah Hon Leong,
• Hong Ye Chu,
• Shaliza Ibrahim and
• Pichiah Saravanan

Beilstein J. Nanotechnol. 2015, 6, 428–437, doi:10.3762/bjnano.6.43

• possesses an appropriate band gap that ensure the simultaneous formation of superoxide anions (•O2−) and hydroxyl (•OH) radicals for the oxidation of organic compounds [6]. Despite all these advantages, TiO2 has two major drawbacks, which are (1) a wide band gap (ca. 3.2 eV for anatase) that restricts the

• with a size of 17–29 nm. On the other hand, pure anatase TiO2 showed a very poor degradation of AMX (27.5%) after the same time. This was attributed to its own characteristic of having large band gap energy which hinder the absorption in the visible region as shown in our optical absorbance spectrum in

Carrier multiplication in silicon nanocrystals: ab initio results

• Ivan Marri,
• Marco Govoni and
• Stefano Ossicini

Beilstein J. Nanotechnol. 2015, 6, 343–352, doi:10.3762/bjnano.6.33

• energy of the excited carrier is higher than the band gap energy, Eg) decays to a lower energy state by transferring its excess energy to generate extra e–h pairs. When CM involves states of the same nanostructure, the effect is termed one-site CM. Because of the restrictions imposed by energy and

• in terms of the ratio Ei/Eg. The zero of the energy scale is set at the half band gap for each NC system. Dashed horizontal lines in (b) and (c) denote the vacuum energy level. In our calculations, we omit vacuum states, that is, conduction band states with an energy higher than the vacuum energy

Nanoporous Ge thin film production combining Ge sputtering and dopant implantation

• Jacques Perrin Toinin,
• Alain Portavoce,
• Khalid Hoummada,
• Michaël Texier,
• Maxime Bertoglio,
• Sandrine Bernardini,
• Marco Abbarchi and
• Lee Chow

Beilstein J. Nanotechnol. 2015, 6, 336–342, doi:10.3762/bjnano.6.32

• interesting properties for optoelectronic applications. For example, porous Si was shown to exhibit an increased band gap compared to bulk Si due to quantum (Q) size effects, related either to the formation of pseudo Q-wires or Q-dots in the porous structure, depending on the production method [1]. Generally

• the pore size allows for the control of the skeleton size, and thus should allow semiconductor band gap engineering, where the aim is the design of devices able to absorb or emit light at a tunable wavelength. Efficient visible electroluminescence has been achieved with porous Si for different

• applications, since they can lead to multiple exciton generation [7]. In particular, multiple exciton generation has been previously demonstrated in Si nanostructures [8]. Ge has a similar structure to Si, however, it offers several benefits compared to Si such as faster carrier mobility, smaller band gap and

Tunable white light emission by variation of composition and defects of electrospun Al₂O₃–SiO₂ nanofibers

• Jinyuan Zhou,
• Gengzhi Sun,
• Hao Zhao,
• Xiaojun Pan,
• Zhenxing Zhang,
• Yujun Fu,
• Yanzhe Mao and
• Erqing Xie

Beilstein J. Nanotechnol. 2015, 6, 313–320, doi:10.3762/bjnano.6.29

• excessive amounts of Al were added to the sample, the 2A12O3∙1SiO2 (2:1) mullite components formed. It is know from previous work [38][40] that the 3:2 mullites possess a wide band gap in the range of 3.95–5.5 eV, which can be of benefit to the intersystem radiative crossing for ≡Si(Al)–O–C∙=O. However, the

• 2:1 mullites have a wide band gap of 7.7 ± 0.2 eV, which is too wide for our case. Therefore, based on the above analysis, we assign an energy transfer mechanism to describe our PL results, as shown in Figure 5d. First, most of the energy needed for the excitation of radical carbonyl defects (≡Si(Al

• elements [5][6][7][8][9]. Among those materials, Al2O3 is one of the most important materials in the history of ceramics, and has been extensively applied in catalysts, coatings, microelectronics and various devices, due to its excellent physical and chemical stability, high dielectric constant, wide band

Tunable light filtering by a Bragg mirror/heavily doped semiconducting nanocrystal composite

• Ilka Kriegel and
• Francesco Scotognella

Beilstein J. Nanotechnol. 2015, 6, 193–200, doi:10.3762/bjnano.6.18

• : active optical component; electronic band gap nanostructure; localized surface plasmon resonance; photonic crystal; Introduction Optical filters are fundamental components employed in almost all optical setups and devices. For example, they play a very important role in microfluidic devices, which are

• [7][44]. By coupling the engineered Bragg mirror with the Cu2−xSe NC dispersion, we obtain a composite device showing an absorption spectrum that is the sum of the photonic band gap and the plasmon absorption (Figure 3). In Figure 3 the blue curve depicts the absorption spectrum of the Bragg mirror

• alone, characterized by the photonic band gap at around 1 eV. The red curves describe the absorption of the Cu2−xSe NC dispersion for different carrier densities, namely, 1.14, 1.53, 1.95 and 2.58 × 1023 cm−3 for Figure 3a–d, respectively, and as calculated above (Figure 2). The black curve describes

Synthesis of boron nitride nanotubes and their applications

• Saban Kalay,
• Zehra Yilmaz,
• Ozlem Sen,
• Melis Emanet,
• Emine Kazanc and
• Mustafa Çulha

Beilstein J. Nanotechnol. 2015, 6, 84–102, doi:10.3762/bjnano.6.9

• chemical and physical properties. In contrast to CNTs, their electrical properties are not dependent on their chirality and diameter since they have a large band gap of about 5.5 eV. BNNTs also have excellent radiation shielding properties when compared to CNTs [4]. Since the BNNTs are composed of B and N

• have a partially ionic character, which causes a gap between the valence and conduction bands. Therefore, the B–N bonds behave as a wide band gap semiconductor. Some relevant properties of BNNTs are as follows: high hydrophobicity, resistance to oxidation and heat, high hydrogen storage capacity and

• and optical band gap properties was evaluated [91]. Two intense blue emission peaks at ~480 nm and ~365 nm were observed upon encapsulation of BNNTs with Ni. The time-resolved photoluminescence spectroscopy (TRPL) provided a photoluminescence spectrum with a bi-exponential decay of 280 ps. It was

Bright photoluminescence from ordered arrays of SiGe nanowires grown on Si(111)

• D. J. Lockwood,
• N. L. Rowell,
• A. Benkouider,
• A. Ronda,
• L. Favre and
• I. Berbezier

Beilstein J. Nanotechnol. 2014, 5, 2498–2504, doi:10.3762/bjnano.5.259

• = 0.14. Both of these concentrations values, as determined from PL, are in agreement with the target value. The NWs are too large in diameter for a quantum confinement induced energy shift in the band gap. Nevertheless, NW PL is readily observed, indicating that efficient carrier recombination is

• ) quantum confinement in conjunction with their associated optical properties [1][2][3][4][5][6]. However, in order to fully implement these new properties, strict control is needed over the NW location, uniformity, composition, and size. By exploiting such band gap engineering, directly allowed transitions

• volume of 0.006 µm3) and thus the carriers have to be recombining efficiently within the wires to produce this light emission at the SiGe-alloy band gap energy. We know from earlier studies of SiGe etched wires [32] and dots [33] that just the spatial confinement of carriers is sufficient to produce the

Low-cost plasmonic solar cells prepared by chemical spray pyrolysis

• Erki Kärber,
• Atanas Katerski,
• Ilona Oja Acik,
• Valdek Mikli,
• Arvo Mere,
• Ilmo Sildos and
• Malle Krunks

Beilstein J. Nanotechnol. 2014, 5, 2398–2402, doi:10.3762/bjnano.5.249

• with a band gap of 1.5 eV that is often used as a photovoltaic absorber. Previously published, related work by our research group regarding CIS-based solar cells includes: the synthesis and properties of CIS [5][6], application of CIS in extremely thin absorber solar cells based on ZnO nanorods [7

Synthesis of radioactively labelled CdSe/CdS/ZnS quantum dots for in vivo experiments

• Gordon M. Stachowski,
• Christoph Bauer,
• Christian Waurisch,
• Denise Bargheer,
• Peter Nielsen,
• Jörg Heeren,
• Stephen G. Hickey and
• Alexander Eychmüller

Beilstein J. Nanotechnol. 2014, 5, 2383–2387, doi:10.3762/bjnano.5.247

• (allowing excitation energies higher than the band gap energy to be freely selected), narrow emission spectra, long emission lifetimes, photo- and chemical-stability, etc. [5][9][10]. Although they offer many advantages, it is important to evaluate the toxicity [11] of nano-scale materials, particularly for

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

• semiconductors. Among them, ZnO (with a high band gap of 3.37 eV) [1][2] has been recognized as one of the most popular semiconducting materials for device fabrication due to its excellent electrical and optical properties [3][4]. Much work has been demonstrated for heterojunctions based on n- and p-type ZnO

• . Additionally, the built-in potential was found to be 1.6 V. These results suggest that the device could be used in high voltage applications, which is an advantage compared to Si-based devices. UV illumination-dependent performance of the diode could also be utilized in space applications where wide band gap

• minimum value at the built-in voltage. The extension of the 1/C2–voltage curve to 1/C2 = 0 gives the built-in voltage [3][9][10], which was found to be 1.6 V (Figure 3). This high value for the built-in voltage is assigned to the low intrinsic carrier concentration of p-ZnO. Since the band gap of p-ZnO is

Electrical contacts to individual SWCNTs: A review

• Wei Liu,
• Christofer Hierold and
• Miroslav Haluska

Beilstein J. Nanotechnol. 2014, 5, 2202–2215, doi:10.3762/bjnano.5.229

• the metal–semiconductor interface and lead to the so-called Fermi level pinning effect, that is, when the Fermi level tends to be fixed at a constant position in the band gap of the semiconductor [13]. The net result is that the Schottky barrier height is less sensitive to the work function difference

• ambipolar and to fully n-type. Assuming the intrinsic Fermi level of SWCNTs is in the middle of the band gap (i.e., the intrinsic work function of the SWCNTs is approximated as the electron affinity plus half of the bandgap: ), the corresponding Schottky barrier height for a metal with a low work function

• can be estimated as where and represent the work function of metal and SWCNT, respectively, and Eg is the band gap of the SWCNT, which is inversely proportional to its diameter (approximated as 0.71 ≈ 1.1/d [19][20][21]). For a CNFET with a Schottky barrier (SB) at the contacts, the electrical

Influence of stabilising agents and pH on the size of SnO₂ nanoparticles

• Olga Rac,
• Patrycja Suchorska-Woźniak,
• Marta Fiedot and
• Helena Teterycz

Beilstein J. Nanotechnol. 2014, 5, 2192–2201, doi:10.3762/bjnano.5.228

• dioxide; Introduction Tin dioxide is an n-type semiconductor with a band gap width of 3.6 eV. It is characterised by good photocatalytic properties and in its presence, decomposition of an organic dye in the visible range of the electromagnetic spectrum may takes place [1]. Moreover, SnO2 is widely used

Nanometer-resolved mechanical properties around GaN crystal surface steps

• Jörg Buchwald,
• Marina Sarmanova,
• Bernd Rauschenbach and
• Stefan G. Mayr

Beilstein J. Nanotechnol. 2014, 5, 2164–2170, doi:10.3762/bjnano.5.225

• a material of great interest due to its application as a wide-band-gap semiconductor especially for optoelectronic devices [7][8]. Additionally, it is known that GaN can exhibit terraces ranging from monoatomic to a few lattice parameters in step height [9][10]. In principle, the results of this

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

• reported for SFS and DFS in Figure 5 and Figure 6 for the visible and the UV range, respectively. The higher QE of SFS with respect to DFS at lower wavelengths in the visible light range (Figure 5) can be attributed to the contribution to the photo-generated charges from the near-band-gap light absorption

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

• in between a nanoparticle and its image. The large supercell size reflects then into a great number of plane waves, which is independent on the ratio between the volumes of matter and vacuum. III.2 Theoretical prediction of observables III.2.1 Optical response: The indirect band-gap nature of bulk Si