Fabrication and characterization of Si_1−xGe_x nanocrystals in as-grown and annealed structures: a comparative study

• Muhammad Taha Sultan,
• Adrian Valentin Maraloiu,
• Ionel Stavarache,
• Jón Tómas Gudmundsson,
• Andrei Manolescu,
• Valentin Serban Teodorescu,
• Magdalena Lidia Ciurea and
• Halldór Gudfinnur Svavarsson

Beilstein J. Nanotechnol. 2019, 10, 1873–1882, doi:10.3762/bjnano.10.182

• the advantage of a bandgap fine-tuning by varying the Ge atomic fraction [5][6]. These properties are useful for optoelectronic devices working in the visible to far-infrared region [4][7]. Issues commonly observed with the fabrication of such structures include inhomogeneity at the matrix

• to surface polarization effects due to local fields, which play a crucial role in systems characterized by strong charge inhomogeneity. Further, the development of strain in the structure influences the size and shape of the NCs, thus resulting in a change of the bandgap energy. A common method to

• possible. An increased number of dangling bonds increases the number of localized states in the band structure along with an increase in non-radiative centers (Pb) [48][49]. This results in a broadening of the energy width of localized states with annealing temperature, resulting in bandgap alteration

Prestress-loading effect on the current–voltage characteristics of a piezoelectric p–n junction together with the corresponding mechanical tuning laws

• Wanli Yang,
• Shuaiqi Fan,
• Yuxing Liang and
• Yuantai Hu

Beilstein J. Nanotechnol. 2019, 10, 1833–1843, doi:10.3762/bjnano.10.178

• present are third-generation semiconductors, for instance, ZnO, GaN, CdS, and AlN, with wide bandgap, high breakdown electric field, high thermal conductivity, and even mechanical tunability [3]. They show numerous application prospects in electric devices and sensors, such as energy harvesters [4][5][6

Remarkable electronic and optical anisotropy of layered 1T’-WTe₂ 2D materials

• Qiankun Zhang,
• Rongjie Zhang,
• Jiancui Chen,
• Wanfu Shen,
• Chunhua An,
• Xiaodong Hu,
• Mingli Dong,
• Jing Liu and
• Lianqing Zhu

Beilstein J. Nanotechnol. 2019, 10, 1745–1753, doi:10.3762/bjnano.10.170

• its semi-metal bandgap structure and high anisotropy. In addition to angle-dependent photodetectors, its angle-resolved photoelectric properties may permit the development of plasmonic devices in which the surface plasmon polariton frequency has a highly directional dependence on the wave vector

• . Besides, the semi-metal bandgap structure allows various energy band engineering methods [36][37] to be explored for the promising application in electronic and photonic devices [38][39][40][41]. In general, due to its highly anisotropic nature, 1T’-WTe2 offers optimistic prospects for the applications in

Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation

• Dominik Wrana,
• Karol Cieślik,
• Wojciech Belza,
• Christian Rodenbücher,
• Krzysztof Szot and
• Franciszek Krok

Beilstein J. Nanotechnol. 2019, 10, 1596–1607, doi:10.3762/bjnano.10.155

• ]). Strontium titanate, SrTiO3, is a perfect example of a semiconductor with a wide bandgap of 3.2 eV and also a model perovskite oxide. Ti4+ cations provide no electrons for the d-band, which can participate in conductivity. Strontium titanate finds many applications as a dielectric ceramic material [15] but

Graphynes: an alternative lightweight solution for shock protection

• Kang Xia,
• Haifei Zhan,
• Aimin Ji,
• Jianli Shao,
• Yuantong Gu and
• Zhiyong Li

Beilstein J. Nanotechnol. 2019, 10, 1588–1595, doi:10.3762/bjnano.10.154

• [8]. GY has a non-zero bandgap, which indicates a potential application in next-generation carbon-based semiconductors [9]. In addition, the properties of GYs are highly tunable through the modification of the topology. For instance, GYs are found to absorb light in the HOMO–LUMO band and the energy

Rapid thermal annealing for high-quality ITO thin films deposited by radio-frequency magnetron sputtering

• Petronela Prepelita,
• Ionel Stavarache,
• Doina Craciun,
• Florin Garoi,
• Catalin Negrila,
• Beatrice Gabriela Sbarcea and
• Valentin Craciun

Beilstein J. Nanotechnol. 2019, 10, 1511–1522, doi:10.3762/bjnano.10.149

• treated ITO films is essential in assessing the advantages of the RTA procedure. To obtain information on the bandgap width, absorption coefficient, refractive index, extinction coefficient, dielectric permittivity, position of the impurity levels in the bandgap and characteristics of the optical

• transitions, we plotted and studied the transmission spectra of the ITO thin films (Figure 5). These polycrystalline thin films show considerable promise for integration into photovoltaic structures, having the bandgap width close to the optimum value of 3.7 eV [39]. Following the RTA process, the ITO thin

• energy of the oscillator, E0, and dispersion energy, Ed [44] as: where ν is the photon frequency. From the graphical representation (n2 − 1)−1 = f [(hν)2] we get the slope (E0Ed)−1, where E0 is considered to be an average of the bandgap energy of semiconductor and has the expression E0 ≈ 2Eg. The optical

Synthesis of P- and N-doped carbon catalysts for the oxygen reduction reaction via controlled phosphoric acid treatment of folic acid

• Rieko Kobayashi,
• Takafumi Ishii,
• Yasuo Imashiro and
• Jun-ichi Ozaki

Beilstein J. Nanotechnol. 2019, 10, 1497–1510, doi:10.3762/bjnano.10.148

• ]. Strelko et al. used theoretical methods to establish an interesting relationship between the bandgap energy of a given catalyst and its ability to promote reactions involving electron transfer [21]. Moreover, P-doping of graphitic layers was revealed to have an effect similar to that of N-doping and hence

BiOCl/TiO₂/diatomite composites with enhanced visible-light photocatalytic activity for the degradation of rhodamine B

• Minlin Ao,
• Kun Liu,
• Xuekun Tang,
• Zishun Li,
• Qian Peng and
• Jing Huang

Beilstein J. Nanotechnol. 2019, 10, 1412–1422, doi:10.3762/bjnano.10.139

• and high carrier utilization rate with slightly reduced bandgap, which will effectively improve the photocatalytic activity. According to the discussion and analysis of the above results, the possible degradation mechanism of RhB by BTD composites was demonstrated in Figure 11. The result shows that

Construction of a 0D/1D composite based on Au nanoparticles/CuBi₂O₄ microrods for efficient visible-light-driven photocatalytic activity

• Weilong Shi,
• Mingyang Li,
• Hongji Ren,
• Feng Guo,
• Xiliu Huang,
• Yu Shi and
• Yubin Tang

Beilstein J. Nanotechnol. 2019, 10, 1360–1367, doi:10.3762/bjnano.10.134

• photocatalysis as an advanced green technology has been widely studied and applied for the removal of organic pollutants from water [1][2][3]. The catalytic activity of many wide-bandgap (Eg) semiconductor photocatalysts is restricted to UV light radiation, which is only 5% of the solar spectrum. Hence, the

• novel visible-light-driven photocatalysts. Due to the valence-band hybridization of O 2p and Bi 6s, the bismuth-based photocatalysts possess a relatively narrow bandgap. Moreover, benefiting from the filled Bi 6s band of Bi3+ or the empty 6s band of Bi5+, Bi-containing compounds strongly absorb visible

• the absolute electronegativity of the photocatalyst, Ee is the energy of the free electrons (4.5 eV) on the hydrogen scale, and Eg is the bandgap width of the photocatalyst. Thus, the VB and CB positions of CBO are calculated to be about 1.13 eV and −0.63 eV, respectively. Under irradiation with

Green fabrication of lanthanide-doped hydroxide-based phosphors: Y(OH)₃:Eu³⁺ nanoparticles for white light generation

• Tugrul Guner,
• Anilcan Kus,
• Mehmet Ozcan,
• Aziz Genc,
• Hasan Sahin and
• Mustafa M. Demir

Beilstein J. Nanotechnol. 2019, 10, 1200–1210, doi:10.3762/bjnano.10.119

• bandgap of 3.83 eV, some midgap states emerge after the interstitial doping of Eu. The energy bandgap of the host at the vicinity of doped region increases to 4.28 eV. The band and orbital decomposed charge density presented in Figure 5b shows that the midgap state is formed by strongly hybridized Eu and

Photoactive nanoarchitectures based on clays incorporating TiO₂ and ZnO nanoparticles

• Eduardo Ruiz-Hitzky,
• Pilar Aranda,
• Marwa Akkari,
• Nithima Khaorapapong and
• Makoto Ogawa

Beilstein J. Nanotechnol. 2019, 10, 1140–1156, doi:10.3762/bjnano.10.114

• @montmorillonite materials can be synthesized from a Zn solution and cetyltrimethylammonium (CTA)-montmorillonite organoclays. In these materials, the bandgap energy of ZnO is decreased compared to bare ZnO NPs, which results in a faster photodegradation of MB. In experiments to prepare ZnO@clay nanoarchitectures

• perspectives Nanoparticulated TiO2 has almost the same bandgap characteristics than ZnO, with bandgap energies of 3.20 eV and 3.37 eV, respectively [48][134][135][136]. Therefore, the photocatalytic capability of both types of NPs should be quite similar. Apart from these large bandgap energy values, both

• transition metals or with other semiconductors. Among them, semiconductor heterojunctions have attracted great attention [139]. The doping of TiO2 and ZnO NPs with the aim to conveniently tuning the bandgap energy values can be a suitable option. In this context, it has been verified for both types of NPs, a

CuInSe₂ quantum dots grown by molecular beam epitaxy on amorphous SiO₂ surfaces

• Henrique Limborço,
• Pedro M.P. Salomé,
• Rodrigo Ribeiro-Andrade,
• Jennifer P. Teixeira,
• Nicoleta Nicoara,
• Kamal Abderrafi,
• Joaquim P. Leitão,
• Juan C. Gonzalez and
• Sascha Sadewasser

Beilstein J. Nanotechnol. 2019, 10, 1103–1111, doi:10.3762/bjnano.10.110

• bandgap and in agreement with the distribution of sizes. A blue-shift of the luminescence is observed as the average size of the nanodots gets smaller, evidencing quantum confinement in all samples. By using simple quantum confinement calculations, we correlate the photoluminescence peak emission energy

• formation of a Cu–In–Se ordered defect compound, which has been reported to form along the tie-line of the (Cu2Se)x–(In2Se3)1−x pseudo-binary system [38][39], and which has a bandgap energy very close to that of CuInSe2 [40]. In this compositional region, i.e., low amounts of Cu compared with In, the so

• show in detail the spectra in Figure 4c–e. The dashed line indicates the bulk bandgap of CIS (1.04–1.05 eV) [45][46]. It is clear that all samples show peak emission at energies above the bulk bandgap, which we preliminarily explain by a quantum confinement effect due to the small mean size of the

Electronic and magnetic properties of doped black phosphorene with concentration dependence

• Ke Wang,
• Hai Wang,
• Min Zhang,
• Yan Liu and
• Wei Zhao

Beilstein J. Nanotechnol. 2019, 10, 993–1001, doi:10.3762/bjnano.10.100

• structures of Si- and S-doped phosphorene without spin polarization always show metallic states suggesting the bandgap is insensitive to the in-plane size of the supercell and the dopant content. However, the results are fairly different once the spin polarization is taken into account. The band structures

• graphene has led to extensive research efforts on two-dimensional (2D) materials. Although graphene exhibits large carrier mobility and intriguing mechanical properties, its zero bandgap impedes its application in spintronic devices [1][2]. Subsequently, 2D transition-metal dichalcogenides (TMDs) have

• received enormous attention [3][4]. While the electronic properties of TMDs range from metallic (such as NbS2) [5] to semiconducting (such as WS2) [6], the low carrier mobility limits the application of these materials. Recently, black phosphorene has attracted research interest owing to its direct bandgap

Experimental study of an evanescent-field biosensor based on 1D photonic bandgap structures

• Jad Sabek,
• Francisco Javier Díaz-Fernández,
• Luis Torrijos-Morán,
• Zeneida Díaz-Betancor,
• Ángel Maquieira,
• María-José Bañuls,
• Elena Pinilla-Cienfuegos and
• Jaime García-Rupérez

Beilstein J. Nanotechnol. 2019, 10, 967–974, doi:10.3762/bjnano.10.97

• Química, Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico IDM, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain 10.3762/bjnano.10.97 Abstract A photonic bandgap (PBG) biosensor has been developed for the label-free detection

• sites towards the target sample. Then, the biofunctionalized PBG biosensor has been used to perform a direct and real-time detection of the target BSA antigen. Keywords: evanescent field; half-antibodies; light-assisted immobilization; photonic bandgap sensor; SNOM characterization; Introduction The

• femtomolar range for oligonucleotides detection [6]. A particular type of photonic sensing devices are photonic bandgap (PBG) biosensors based on evanescent-wave detection [7]. PBG structures consist of a periodic dielectric configuration for which the propagation of a certain wavelength range is forbidden

Structural and optical properties of penicillamine-protected gold nanocluster fractions separated by sequential size-selective fractionation

• Xiupei Yang,
• Zhengli Yang,
• Fenglin Tang,
• Jing Xu,
• Maoxue Zhang and
• Martin M. F. Choi

Beilstein J. Nanotechnol. 2019, 10, 955–966, doi:10.3762/bjnano.10.96

• transition of the HOMO–LUMO bandgap of the subnanometer-sized NCs [42]. For the final precipitated fraction (F90%, Au11 clusters), its UV absorption decays to visible light in an approximately exponential manner with no detectable surface plasmon spectral bands. All the normalized PL spectra for the crude

Synthesis of novel C-doped g-C₃N₄ nanosheets coupled with CdIn₂S₄ for enhanced photocatalytic hydrogen evolution

• Jingshuai Chen,
• Chang-Jie Mao,
• Helin Niu and
• Ji-Ming Song

Beilstein J. Nanotechnol. 2019, 10, 912–921, doi:10.3762/bjnano.10.92

• have been prepared for photocatalytic hydrogen evolution under visible-light illumination. This approach not only results in a material with a narrower bandgap but also in the efficient charge transfer and separation, realizing the synergistic effect of C-doping and composite nanostructures. It was

Comparing a porphyrin- and a coumarin-based dye adsorbed on NiO(001)

• Sara Freund,
• Antoine Hinaut,
• Nathalie Marinakis,
• Edwin C. Constable,
• Ernst Meyer,
• Catherine E. Housecroft and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2019, 10, 874–881, doi:10.3762/bjnano.10.88

• Kelvin probe force microscopy measurements. Keywords: coumarin; Kelvin probe force microscopy; metal oxide; molecular resolution; nickel oxide (NiO); non-contact atomic force microscopy; porphyrin; Introduction With regard to its use in dye-sensitized solar cells (DSSCs), the wide-bandgap n-type

• -bandgap p-type semiconductors, such as NiO, and their functionalization with sensitizers, have been less extensively studied by using SPM [12][13][14][15]. NiO was the first reported p-type wide-bandgap semiconductor [16], and can be used for the fabrication of p-type DSSCs with photoactive cathodes, a

Electronic properties of several two dimensional halides from ab initio calculations

• Mohamed Barhoumi,
• Ali Abboud,
• Lamjed Debbichi,
• Moncef Said,
• Torbjörn Björkman,
• Dario Rocca and
• Sébastien Lebègue

Beilstein J. Nanotechnol. 2019, 10, 823–832, doi:10.3762/bjnano.10.82

• materials [4][5][6][7]. Although graphene is the most extensively studied 2D crystal [8], graphene is gapless, and this lack of a bandgap hampers its application in electronic and optoelectronic devices. This has motivated the research on other two-dimensional (2D) materials with a finite bandgap, such as

• ] was used. Similar parameters were employed for hybrid Heyd–Scuseria–Ernzerhof (HSE) calculations [38], that were performed to obtain accurate values for the bandgap. Sufficient spacing (more than 17 Å) was put between the monolayers to avoid significant interactions between the periodically repeated

• Brillouin zone. The resulting band structures using HSE are presented in the following paragraphs. In Figure 7, we present the band structures of the AcOBr, BaFBr, BiOBr, and CaFBr monolayers. We found that the AcOBr, BaFBr, and CaFBr monolayers are direct-bandgap semiconductors with the valence-band

Trapping polysulfide on two-dimensional molybdenum disulfide for Li–S batteries through phase selection with optimized binding

• Sha Dong,
• Xiaoli Sun and
• Zhiguo Wang

Beilstein J. Nanotechnol. 2019, 10, 774–780, doi:10.3762/bjnano.10.77

• is the energetically stable phase with semiconductor characteristics, in which the S atoms are located in the lattice positions of a hexagonal close-packed structure. 1T'-MoS2 is a meta-stable phase with narrow bandgap, in which each Mo atom is octahedrally coordinated with six S atoms. The phase

• '-MoS2 monolayers used in the work are shown in Figure 1a and Figure 1b, respectively. The electronic band structures along high-symmetry points are shown in Figure 1c and Figure 1d, respectively. The 2H-MoS2 monolayer is a semiconductor with a direct bandgap of 1.67 eV, both the conduction band minimum

• (CBM) and valence band maximum (VBM) are located at the K point, which is consistent with previous DFT calculations [39]. 1T'-MoS2 is a narrow-bandgap semiconductor with a bandgap of 0.15 eV. Various intermediates, Li2Sx (x = 1–8), of LPSs were observed in Li–S batteries [40]. The optimized atomic

Renewable energy conversion using nano- and microstructured materials

• Harry Mönig and
• Martina Schmid

Beilstein J. Nanotechnol. 2019, 10, 771–773, doi:10.3762/bjnano.10.76

• increasing the absorption or the area of a chemically reactive surface, a very established approach concerns bandgap engineering by varying the size and shape of nanoparticles, which enables, for instance, the optimization of the optoelectronic material properties to the solar spectrum [13]. Furthermore

Ultrasonication-assisted synthesis of CsPbBr₃ and Cs₄PbBr₆ perovskite nanocrystals and their reversible transformation

• Longshi Rao,
• Xinrui Ding,
• Xuewei Du,
• Guanwei Liang,
• Yong Tang,
• Kairui Tang and
• Jin Z. Zhang

Beilstein J. Nanotechnol. 2019, 10, 666–676, doi:10.3762/bjnano.10.66

• defects or from impurities or from a combination of both [37][38]. Herein, the purified Cs4PbBr6 PNCs did not demonstrate PL emission over the whole visible spectrum due to their wide bandgap (Eg(Cs4PbBr6) = 3.94 eV), while the observed weak PL emission results from a small portion of CsPbBr3 impurities

Direct observation of the CVD growth of monolayer MoS₂ using in situ optical spectroscopy

• Claudia Beatriz López-Posadas,
• Yaxu Wei,
• Wanfu Shen,
• Daniel Kahr,
• Michael Hohage and
• Lidong Sun

Beilstein J. Nanotechnol. 2019, 10, 557–564, doi:10.3762/bjnano.10.57

• , the DT signal at a higher energy of 3.2 eV begins to dominate. Based on its energy position, this feature can be attributed to the absorption of MoO3 [32][33]. As a semiconductor, MoO3 shows a bandgap around 3 eV. Considering the high temperature of the substrate, we can exclude the possibility that

Temperature-dependent Raman spectroscopy and sensor applications of PtSe₂ nanosheets synthesized by wet chemistry

• Mahendra S. Pawar and
• Dattatray J. Late

Beilstein J. Nanotechnol. 2019, 10, 467–474, doi:10.3762/bjnano.10.46

• semimetallic nature and single-layer PtSe2 has a semiconducting nature with a bandgap of 1.2 eV. Bilayer PtSe2 is also a semiconducting material but with a slightly smaller band gap than the monolayer material [19]. This layer-dependent conversion of semimetal-to-semiconductor transition has potential for

Reduced graphene oxide supported C₃N₄ nanoflakes and quantum dots as metal-free catalysts for visible light assisted CO₂ reduction

• Md Rakibuddin and
• Haekyoung Kim

Beilstein J. Nanotechnol. 2019, 10, 448–458, doi:10.3762/bjnano.10.44

• of photo-induced electron–hole pairs and insufficient adsorption of CO2 at the catalyst surface are crucial problems preventing effective catalyst performance and CO2 reduction [11]. An ideal photocatalyst for CO2 conversion should possess a narrow bandgap and good light-harvesting properties, proper

Geometrical optimisation of core–shell nanowire arrays for enhanced absorption in thin crystalline silicon heterojunction solar cells

• Robin Vismara,
• Olindo Isabella,
• Andrea Ingenito,
• Fai Tong Si and
• Miro Zeman

Beilstein J. Nanotechnol. 2019, 10, 322–331, doi:10.3762/bjnano.10.31

• reflected by the top surface of the nanowire, thus increasing total reflection. Anttu et al. suggest another possible explanation for the optimal cross section value [19]. In their work on III–V semiconductors nanowire arrays, they observed the presence of optimum, bandgap-dependent nanowire diameter values