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Chao Zeng, Adrian Gonzalez-Alvarez, Emily Orenstein, Jim A Field, Farhang Shadman, Reyes Sierra-Alvarez
III-V materials such as indium arsenide (InAs) and gallium arsenide (GaAs) are increasingly used in electronic and photovoltaic devices. The extensive application of these materials may lead to release of III-V ionic species during semiconductor manufacturing or disposal of decommissioned devices into the environment. Although arsenic is recognized as an important contaminant due to its high toxicity, there is a lack of information about the toxic effects of indium and gallium ions. In this study, acute toxicity of As(III), As(V), In(III) and Ga(III) species was evaluated using two microbial assays testing for methanogenic activity and O2 uptake, as well as two bioassays targeting aquatic organisms, including the marine bacterium Aliivibrio fischeri (bioluminescence inhibition) and the crustacean Daphnia magna (mortality)...
February 20, 2017: Ecotoxicology and Environmental Safety
Zhenglu Li, Ting Cao, Meng Wu, Steven G Louie
Artificial lattices have been employed in a broad range of two-dimensional systems, including those with electrons, atoms and photons, in the quest for massless Dirac fermions with high flexibility and controllability. Establishing triangular or hexagonal symmetry, from periodically patterned molecule assembly or electrostatic gating as well as from moiré pattern induced by substrate, has produced electronic states with linear dispersions from two-dimensional electron gas (2DEG) residing in semiconductors, metals and graphene...
February 23, 2017: Nano Letters
Xiren Chen, Qiandong Zhuang, Hayfaa Alradhi, ZhiMing Jin, Liangqing Zhu, Xin Chen, Jun Shao
Photoluminescence (PL) as a conventional yet powerful optical spectroscopy may provide crucial insight into the mechanism of carrier recombination and bandedge structure in semiconductors. In this study, mid-infrared PL measurements on vertically aligned InAs nanowires (NWs) are realized for the first time in a wide temperature range of up to 290 K, by which the radiative recombinations are clarified in the NWs grown on n- and p-type Si substrates, respectively. A dominant PL feature is identified to be from the type-II optical transition across the interfaces between the zinc-blend (ZB) and the wurtzite (WZ) InAs, a lower-energy feature at low temperatures is ascribed to impurity-related transition, and a higher-energy feature at high temperatures originates in the interband transition of the WZ InAs being activated by thermal-induced electron transfer...
February 23, 2017: Nano Letters
Jeremy David, Francesco Rossella, Mirko Rocci, Daniele Ercolani, Lucia Sorba, Fabio Beltram, Mauro Gemmi, Stefano Roddaro
We investigate the metallic phases observed in hybrid metal-GaAs nanowire devices obtained by controlled thermal annealing of Ni/Au electrodes. Devices are fabricated onto a SiN membrane compatible with transmission electron microscopy studies. Energy dispersive X-ray spectroscopy allows us to show that the nanowire body includes two Ni-rich phases that, thanks to an innovative use of electron diffraction tomography, can be unambiguously identified as Ni3GaAs and Ni5As2 crystals. The mechanisms of Ni incorporation leading to the observed phenomenology are discussed...
February 23, 2017: Nano Letters
Tzu-Ging Lin, Sarath Ramadurgam, Chen Yang
Transparent, low resistive contacts are critical for efficient solar energy harvesting devices. It is important to reconsider the material choices and electrode design as devices move from 2D films to 1D nanostructures. In this paper, we study the effectiveness of indium tin oxide (ITO) and metals, such as Ag and Cu, as contacts in 2D and 1D systems. Although ITO has been studied extensively and developed into an effective transparent contact for 2D devices, our results show that effectiveness does not translate to 1D systems...
February 23, 2017: Nano Letters
Vanousheh Rahemi, Nasrin Sarmadian, Willemien Anaf, Koen Janssens, Dirk Lamoen, Bart Partoens, Karolien De Wael
Chrome yellow refers to a group of synthetic inorganic pigments that became popular as an artist's material from the second quarter of the 19th century. The color of the pigment, in which the chromate ion acts as a chromophore, is related to its chemical composition (PbCr1-xSxO4, with 0≤x≤0.8) and crystalline structure (monoclinic/orthorhombic). Their shades range from the yellow-orange to the paler yellow tones with increasing sulfate amount. These pigments show remarkable signs of degradation after limited time periods...
February 23, 2017: Analytical Chemistry
Ning Li, Stephen Bedell, Huan Hu, Shu-Jen Han, Xiao Hu Liu, Katherine Saenger, Devendra Sadana
Flexible and stretchable electronics are becoming increasingly important in many emerging applications. Due to the outstanding electrical properties of single crystal semiconductors, there is great interest in releasing single crystal thin films and fabricating flexible electronics with these conventionally rigid materials. In this study the authors report a universal single crystal layer release process, called "3D spalling," extending beyond prior art. In contrast to the conventional way of removing blanket layers from their substrates, the new process reported here enables 3D control over the shape and thickness of the removed regions, allowing direct formation of arbitrarily shaped structures of released film and locally specified thickness for each region...
February 23, 2017: Advanced Materials
Somnath Chakraborty, A N Resmi, Renuka Pothuraju, K B Jinesh
Chemically reduced graphene oxide (rGO) samples with various degree of reduction were prepared using hydrazine hydrate as the reducing agent. Scanning tunnelling microscope (STM) imaging shows that rGO contains rows of randomly distributed patches of epoxy groups. The local density of states (LDOS) of the rGO samples were mapped with scanning tunnelling spectroscopy (STS), which shows that the bandgap in rGO originates from the epoxide regions itself. The Fermi level of the epoxide regions is shifted towards the valence band, making rGO locally p-type and a ranges of bandgaps from 0-2...
February 23, 2017: Nanotechnology
Rebecca D McAuliffe, Christopher A Miller, Xiao Zhang, Benjamin S Hulbert, Ashfia Huq, Clarina Dela Cruz, André Schleife, Daniel P Shoemaker
We present the compound K2Sn3O7, a Sn(4+)-containing oxide with a unique structure type among oxides. The compound is orthorhombic and reminiscent of an offset hollandite, where open channels hold a row of four K(+) per channel per cell. UV-visible spectroscopy indicates a wide band gap semiconductor, which is confirmed by first-principles electronic-structure calculations of band structures, densities of states, and optical properties. The continued discovery of new structure types in ternary tin oxides should remain a priority for the identification of prospective ion conductors and transparent conducting compounds...
February 23, 2017: Inorganic Chemistry
Ayelet Vilan, David Cahen
Inserting molecular monolayers within metal/semiconductor interfaces provides one of the most powerful expressions of how minute chemical modifications can affect electronic devices. This topic also has direct importance for technology as it can help improve the efficiency of a variety of electronic devices such as solar cells, LEDs, sensors, and possible future bioelectronic ones. The review covers the main aspects of using chemistry to control the various aspects of interface electrostatics, such as passivation of interface states and alignment of energy levels by intrinsic molecular polarization, as well as charge rearrangement with the adjacent metal and semiconducting contacts...
February 23, 2017: Chemical Reviews
Kamal Sbargoud, Masashi Mamada, Tanguy Jousselin-Oba, Yasunori Takeda, Shizuo Tokito, Abderrahim Yassar, Jérôme Marrot, Michel Frigoli
The benchmark of soluble organic semiconductors based on acenes is the 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-PEN). However TIPS-PEN still suffers from photoinduced oxidation due to its low aromaticity. Increasing the aromaticity while keeping similar optical and electrochemical properties and shape suitable for good transport can be achieved with two-dimensional polycyclic aromatic hydrocarbons (2D-PAHs). Herein, we present an efficient synthesis and characterization of bistetracene derivatives that exhibit a band gap up to 1...
February 23, 2017: Chemistry: a European Journal
I Arrechea-Marcos, P de Echegaray, M J Mancheño, M C Ruiz Delgado, M M Ramos, J A Quintana, J M Villalvilla, M A Díaz-García, J T López Navarrete, R Ponce Ortiz, J L Segura
Amphiphilic and lipophilic donor-acceptor naphthalimide-oligothiophene assemblies exhibiting almost identical intramolecular properties, but differing in their intermolecular interactions, have been synthesized. Here we analyze the effect of replacing the normally used lipophilic alkyl chains with hydrophilic ones in directing molecular aggregation from an antiparallel to a parallel stacking. This different molecular packing of the amphiphilic, NIP-3TAmphi, and lipophilic, NIP-3TLipo, systems is assessed by electronic spectroscopies, scanning electronic microscopy and DFT quantum-chemical calculations...
February 22, 2017: Physical Chemistry Chemical Physics: PCCP
Seokhyun Yoon, Si Joon Kim, Young Jun Tak, Hyun Jae Kim
We report a method for fabricating solution-processed quaternary In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) at low annealing temperatures using a vertical diffusion technique (VDT). The VDT is a deposition process for spin-coating binary and ternary oxide layers consecutively and annealing at once. With the VDT, uniform and dense quaternary oxide layers were fabricated at lower temperatures (280 °C). Compared to conventional IGZO and ternary In-Zn-O (IZO) thin films, VDT IGZO thin film had higher density of the metal-oxide bonds and lower density of the oxygen vacancies...
February 23, 2017: Scientific Reports
Jing Li, Laihao Luo, Hongwen Huang, Chao Ma, Zhizhen Ye, Jie Zeng, Haiping He
Fundamental to understanding and predicting the optoelectronic properties of semiconductors is the basic parameters of excitons such as oscillator strength and exciton binding energy. However, such knowledge of CsPbBr3 perovskite, a promising optoelectronic material, is still unexplored. Here we demonstrate that quasi-two-dimensional (quasi-2D) CsPbBr3 nanoplatelets (NPLs) with 2D exciton behaviors serve as an ideal system for the determination of these parameters. It is found that the oscillator strength of CsPbBr3 NPLs is up to 1...
February 23, 2017: Journal of Physical Chemistry Letters
Ying Xie, Bo Zhang, Shuxian Wang, Dong Wang, Aizhu Wang, Zeyan Wang, Haohai Yu, Huaijin Zhang, Yanxue Chen, Mingwen Zhao, Baibiao Huang, Liangmo Mei, Jiyang Wang
Photodetectors with excellent detecting properties over a broad spectral range have advantages for the application in many optoelectronic devices. Introducing imperfections to the atomic lattices in semiconductors is a significant way for tuning the bandgap and achieving broadband response, but the imperfection may renovate their intrinsic properties far from the desire. Here, by controlling the deviation from the perfection of the atomic lattice, ultrabroadband multilayer MoS2 photodetectors are originally designed and realized with the detection range over 2000 nm from 445 nm (blue) to 2717 nm (mid-infrared)...
February 23, 2017: Advanced Materials
Yan Liu, Jiebin Niu, Hongjuan Wang, Genquan Han, Chunfu Zhang, Qian Feng, Jincheng Zhang, Yue Hao
Well-behaved Ge quantum well (QW) p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) were fabricated on silicon-on-insulator (SOI) substrate. By optimizing the growth conditions, ultrathin fully strained Ge film was directly epitaxially grown on SOI at about 450 °C using ultra-high vacuum chemical vapor deposition. In situ Si2H6 passivation of Ge was utilized to form a high-quality SiO2/Si interfacial layer between the high-κ dielectric and channels. Strained Ge QW pMOSFETs achieve the significantly improved effective hole mobility μ eff as compared with the relaxed Si and Ge control devices...
December 2017: Nanoscale Research Letters
Yuting Wang, Muhammad Shahid, Jing Cheng, Hiroki Nishijima, Wei Pan
Transparent electrodes based on a metal nanotrough network show superior electrical and optical properties. However, most metal networks fabricated by electrospinning are formed as film electrodes and hard to be patterned for the geometry shape of the device without any loss. Herein, we fabricate a high-transparent and flexible photodetector via a simple controlled electrospinning method. Owning to its trough- and belt-like geometry of Pt network electrodes, up to 83% transmittance can be obtained when the sheet resistances is 16Ω/sq, which may be the best performance for Pt-based transparent electrodes at present...
February 22, 2017: Nanotechnology
Xiaofeng Liu, Qiangbing Guo, Jianrong Qiu
Low-dimensional (LD) materials demonstrate intriguing optical properties, which lead to applications in diverse fields, such as photonics, biomedicine and energy. Due to modulation of electronic structure by the reduced structural dimensionality, LD versions of metal, semiconductor and topological insulators (TIs) at the same time bear distinct nonlinear optical (NLO) properties as compared with their bulk counterparts. Their interaction with short pulse laser excitation exhibits a strong nonlinear character manifested by NLO absorption, giving rise to optical limiting or saturated absorption associated with excited state absorption and Pauli blocking in different materials...
February 22, 2017: Advanced Materials
Xu Lin, Mika Suzuki, Marina Gushiken, Mitsuaki Yamauchi, Takashi Karatsu, Takahiro Kizaki, Yuki Tani, Ken-Ichi Nakayama, Mitsuharu Suzuki, Hiroko Yamada, Takashi Kajitani, Takanori Fukushima, Yoshihiro Kikkawa, Shiki Yagai
The design of molecular systems with high-fidelity self-assembly pathways that include several levels of hierarchy is of primary importance for the understanding of structure-function relationships, as well as for controlling the functionality of organic materials. Reported herein is a high-fidelity self-assembly system that comprises two hydrogen-bonding molecular semiconductors with regioisomerically attached short alkyl chains. Despite the availability of both discrete cyclic and polymeric linear hydrogen-bonding motifs, the two regioisomers select one of the two motifs in homogeneous solution as well as at the 2D-confined liquid-solid interface...
February 22, 2017: Scientific Reports
O V Shramkova, G P Tsironis
The combinatorial frequency generation (CFG) in active periodic semiconductor-dielectric structures has been explored through illumination by a pair of pump waves with dissimilar frequencies and incidence angles. We study the influence of gain on linear refraction properties of the stack and on the efficiency of the mixing processes by the system with the resistive character of nonlinearity. We demonstrate that the introduction of gain dielectric material inside the stack not only compensates for losses caused by the collisions of the electrons in semiconductor media but also improves the efficiency of the CFG...
February 22, 2017: Scientific Reports
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