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Prasenjit Kabi, Swetaprovo Chaudhuri, Saptarshi Basu
Nanoscale engineering has traditionally adopted the chemical route of synthesis or opto-chemical techniques like lithography requiring large process times, expensive equipment and an inert environment. Directed self-assembly using evaporation of nanocolloidal droplet can be a potential low-cost alternative across various industries ranging from semiconductors to biomedical systems. It is relatively simple to scale and re-orient the evaporation driven internal flow field in an evaporating droplet which can direct dispersed matter into functional agglomerates...
January 18, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Tim Verhagen, Vaclav Vales, Martin Kalbac, Jana Vejpravova
Graphene is extremely sensitive to optical, electrical and mechanical stimuli, which cause a significant variation of the band structure, thus physiochemical properties. In our work, we report on changes of strain and doping in graphene grown by chemical vapor deposition (CVD) and transferred onto a BaTiO3(100) (BTO) single-crystal. The BTO is known as a ferroelectric material, which undergoes several thermoelastic martensitic phase transitions when it is cooled from 300 K to 10K. In order to enhance the very weak Raman signal of the graphene monolayer (ML) on the BTO, a 15 nm thin gold layer was deposited on top of the graphene ML to benefit from the surface enhanced Raman scattering (SERS)...
January 18, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Diego Lops, Roberto Meneghello, Luca Sbricoli, Gianpaolo Savio, Eriberto Bressan, Edoardo Stellini
PURPOSE: The aim of this in vitro study was to verify whether or not stock and computer-aided design/computer-aided manufacturing (CAD/CAM) abutments show similar precision in the connection with the respective implants. MATERIALS AND METHODS: Ten CAD/CAM titanium abutments were compared with 10 stock titanium abutments. Each abutment fit a regular-platform implant (Institute Straumann). Implants and abutments were measured independently and then connected. During the connection procedure, the torque was measured using a six-axes load cell...
January 2018: International Journal of Oral & Maxillofacial Implants
Sarah Loebner, Nino Lomadze, Alexey Kopyshev, Markus Koch, Olga Guskova, Marina Grenzer Saphiannikova, Svetlana A Santer
We report on light induced deformation of colloidal spheres consisting of azobenzene containing polymers. The colloids of the size between 60nm and 2m in diameter were drop casted on a glass surface and irradiated with linearly polarized light. It was found that colloidal particles can be deformed up to ca. 6 times of their initial diameter. The maximum degree of deformation depends on the irradiation wavelength and intensity, as well as on colloidal particles size. Based on recently proposed theory [V. Toshchevikov et al...
January 16, 2018: Journal of Physical Chemistry. B
Ke Wang, Kristiaan De Greve, Luis A Jauregui, Andrey Sushko, Alexander High, You Zhou, Giovanni Scuri, Takashi Taniguchi, Kenji Watanabe, Mikhail D Lukin, Hongkun Park, Philip Kim
Electrical confinement and manipulation of charge carriers in semiconducting nanostructures are essential for realizing functional quantum electronic devices1-3. The unique band structure4-7 of atomically thin transition metal dichalcogenides (TMDs) offers a new route towards realizing novel 2D quantum electronic devices, such as valleytronic devices and valley-spin qubits 8 . 2D TMDs also provide a platform for novel quantum optoelectronic devices9-11 due to their large exciton binding energy12,13. However, controlled confinement and manipulation of electronic and excitonic excitations in TMD nanostructures have been technically challenging due to the prevailing disorder in the material, preventing accurate experimental control of local confinement and tunnel couplings14-16...
January 15, 2018: Nature Nanotechnology
Bing Wang, Xianghong Niu, Yixin Ouyang, Qionghua Zhou, Jinlan Wang
High carrier mobility and moderate band gap are two key properties of electronic device applications. Two ultrathin two-dimensional (2D) semiconductors, namely Bi2Te2S and Bi2Te2Se nanosheets, with novel electronic and optical properties are predicted based on first-principles calculations. The Bi2Te2S and Bi2Te2Se monolayers own moderate band gaps (~ 0.7 eV) and high electronic mobilities (20000 cm2V-1s-1); and they can absorb sunlight efficiently through the whole incident solar spectrum. Meanwhile, layer-dependent exponential decay band gaps are also unveiled...
January 11, 2018: Journal of Physical Chemistry Letters
Sung-Joo Kwon, Tae-Hee Han, Young-Hoon Kim, Towfiq Ahmed, Hong-Kyu Seo, Hobeom Kim, Dong Jin Kim, Wentao Xu, Byung Hee Hong, Jian-Xin Zhu, Tae-Woo Lee
n-Type doping with (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl) dimethylamine (N-DMBI) reduces a work function (WF) of graphene by ~0.45 eV without significant reduction of optical transmittance. Solution process of N-DMBI on graphene provides effective n-type doping effect and air-stability at the same time. Although neutral N-DMBI act as an electron receptor leaving the graphene p-doped, radical N-DMBI acts as an electron donator leaving the graphene n-doped, which is demonstrated by density functional theory...
January 11, 2018: ACS Applied Materials & Interfaces
Leonardo Midolo, Albert Schliesser, Andrea Fiore
A new class of hybrid systems that couple optical, electrical and mechanical degrees of freedom in nanoscale devices is under development in laboratories worldwide. These nano-opto-electro-mechanical systems (NOEMS) offer unprecedented opportunities to control the flow of light in nanophotonic structures, at high speed and low power consumption. Drawing on conceptual and technological advances from the field of optomechanics, they also bear the potential for highly efficient, low-noise transducers between microwave and optical signals, in both the classical and the quantum domains...
January 2018: Nature Nanotechnology
Fahimeh Dehkhoda, Ahmed Soltan, Nikhil Ponon, Andrew Jackson, Anthony G O'Neill, Patrick Degenaar
This work presents a method to determine the surface temperature of microphotonic medical implants like LEDs. Our inventive step is to use the photonic emitter (LED) employed in an implantable device as its own sensor and develop readout circuitry to accurately determine the surface temperature of the device. There are two primary classes of applications where microphotonics could be used in implantable devices; opto-electrophysiology, and fluorescence sensing. In such scenarios, intense light needs to be delivered to the target...
January 5, 2018: Journal of Neural Engineering
Yurong Yang, Charles Paillard, Bin Xu, Laurent Bellaiche
The present work reviews a series of recent first-principles studies devoted to the description of the interaction of light and strain in ferroelectric and multiferroic materials. Specifically, the modelling schemes used in these works to describe the so-called photostriction and elasto-optic effects are presented, in addition to the results and analysis provided by these ab-initio calculations. In particular, the large importance of the piezoelectric effect in the polar direction in the photostriction of ferroelectric materials is stressed out...
January 4, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Zongxuan Li, Xue Chen, Shaoju Wang, Guang Jin
A flexural support technique for lightweighted Primary Mirror Assembly (PMA) of a space telescope is presented in this article. The proposed three-point flexural mount based on a cartwheel flexure can maintain the surface figure of the PMA in a horizontal optical testing layout. The on-orbit surface error of the PMA causes significant degradation in image quality. On-ground optical testing cannot determine the zero-gravity figure of the PMA due to surface distortion by gravity. We unveiled the crucial fact that through a delicate mounting structure design, the surface figure can remain constant precisely without inducing distinguishable astigmatism when PMA rotates with respect to the optical axis, and the figure can be considered as the zero-gravity surface figure on the orbit...
December 2017: Review of Scientific Instruments
Kai Zhang, Lei Lv, Xiaofen Wang, Yang Mi, Ruiqing Chai, Xinfeng Liu, Guozhen Shen, Aidong Peng, Hui Huang
Organic photodetectors (OPDs) have attracted great attention due to their advantages including tunable response range, easy processability and flexibility. Various conjugated polymers have been developed for high performing OPDs. Herein, a series of tellurophene-based random copolymers containing two typical electron-withdrawing units naphthalene diimide (NDI) and perylene diimide (PDI) are designed and synthesized. Through varying the ratio of PDI/NDI moieties of the analogous polymers, the opto-physical properties and film morphology, together with photodetector performances are systematically tuned...
December 28, 2017: ACS Applied Materials & Interfaces
Suparna Paul, Pritam Ghosh, Samuzal Bhuyan, Subhra Kanti Mukhopadhyay, Priyabrata Banerjee
A dual-channel chromogenic and fluorogenic fused-aromatic-system-based chemoreceptor (2-(benzo[d]thiazol-2-yl)-1-((pyren-8-yl)methylene)hydrazine) (TyM) was designed for ditopic sensitivity towards heavy and transition metal ions (HTMs), such as Cu2+, in an aqueous medium and lethal CN- in a semi-aqueous medium. The chemoreceptor displayed proclivity towards the targeted analytes with a distinct optical response (yellow to colourless in the case of Cu2+ and yellow to bright red for CN-). TyM formed a 2 : 1 adduct with Cu2+ with a detection limit of 40 nM...
December 20, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Siyuan Luo, Li He, Mo Li
The propagation of electrons and photons can respectively have the spin-momentum locking effect which correlates spin with linear momentum. For surface electrons in three-dimensional topological insulators (TIs), their spin is locked to the transport direction. Analogously, photons in optical waveguides carry transverse spin angular momentum which is also locked to the propagation direction. A direct connection between electron and photon spins occurs in TIs due to spin-dependent selection rules of optical transitions...
December 15, 2017: Nature Communications
Annie Kumar, Shuh-Ying Lee, Sachin Yadav, Kian Hua Tan, Wan Khai Loke, Yuan Dong, Kwang Hong Lee, Satrio Wicaksono, Gengchiau Liang, Soon-Fatt Yoon, Dimitri Antoniadis, Yee-Chia Yeo, Xiao Gong
Lasers monolithically integrated with high speed MOSFETs on the silicon (Si) substrate could be a key to realize low cost, low power, and high speed opto-electronic integrated circuits (OEICs). In this paper, we report the monolithic integration of InGaAs channel transistors with electrically pumped GaAs/AlGaAs lasers on the Si substrate for future advanced OEICs. The laser and transistor layers were grown on the Si substrate by molecular beam epitaxy (MBE) using direct epitaxial growth. InGaAs n-FETs with an ION/IOFF ratio of more than 106 with very low off-state leakage and a low subthreshold swing with a minimum of 82 mV/decade were realized...
December 11, 2017: Optics Express
Iurii Kim, Pyry Kivisaari, Jani Oksanen, Sami Suihkonen
Almost all modern inorganic light-emitting diode (LED) designs are based on double heterojunctions (DHJs) whose structure and current injection principle have remained essentially unchanged for decades. Although highly efficient devices based on the DHJ design have been developed and commercialized for energy-efficient general lighting, the conventional DHJ design requires burying the active region (AR) inside a pn-junction. This has hindered the development of emitters utilizing nanostructured ARs located close to device surfaces such as nanowires or surface quantum wells...
December 12, 2017: Materials
Yann Almadori, Nedjma Bendiab, Benjamin Grevin
Atomically thin transition metal dichalcogenides (TMDC) have become a new platform for the development of next-generation opto-electronic and light harvesting devices. Here, we report a Kelvin probe force microscopy (KPFM) investigation carried out on a type-II photovoltaic heterojunction based on WSe2 monolayer flakes and a bilayer MoS2 film stacked in vertical configuration on a Si/SiO2 substrate. Band offset characterized by a significant interfacial dipole is pointed out at the WSe2/MoS2 vertical junction...
December 8, 2017: ACS Applied Materials & Interfaces
Michael C Chong, Nasima Afsharimani, Fabrice Scheurer, Claudia Cardoso, Andrea Ferretti, Deborah Prezzi, Guillaume Schull
Thanks to their highly tunable band gaps, graphene nanoribbons (GNRs) with atomically precise edges are emerging as mechanically and chemically robust candidates for nanoscale light emitting devices of modulable emission color. While their optical properties have been addressed theoretically in depth, only few experimental studies exist, limited to ensemble measurements and without any attempt to integrate them in an electronic-like circuit. Here we report on the electroluminescence of individual GNRs suspended between the tip of a scanning tunneling microscope (STM) and a Au(111) substrate, constituting thus a realistic opto-electronic circuit...
December 7, 2017: Nano Letters
Jenifer R Hajzus, Adam J Biacchi, Son T Le, Curt A Richter, Angela R Hight Walker, Lisa M Porter
Tin(ii) monosulfide (SnS) is a layered, anisotropic material that is of interest as a two-dimensional semiconductor for opto-electronic, thermoelectric, and piezoelectric applications. In this study, the effect of work function on contact behavior was investigated. Ni/Au, Pd/Au, Cr/Au, and Ti/Au contacts were fabricated onto individual, solution-synthesized, p-type SnS nanoribbons. The lower work function metals (Cr and Ti) formed Schottky contacts, whereas the higher work function metals (Ni and Pd) formed ohmic or semi-ohmic contacts...
December 7, 2017: Nanoscale
Jonas Häusler, Robin Niklaus, Ján Minár, Wolfgang Schnick
Grimm-Sommerfeld analogous nitrides MgSiN2, MgGeN2, MnSiN2, MnGeN2, LiSi2N3 and LiGe2N3 (generally classified as II IV N2 and I-IV2-N3) are promising semiconductor materials with great potential for application in (opto)electronics or photovoltaics. A new synthetic approach for these nitride materials was developed using supercritical ammonia as solvent and nitriding agent. Syntheses were conducted in custom-built high-pressure autoclaves with alkali metal amides LiNH2, NaNH2 or KNH2 as ammonobasic mineralizers which accomplish an adequate solubility of the starting materials and promote the formation of reactive intermediate species...
December 4, 2017: Chemistry: a European Journal
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