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Band gap semiconductor

The present paper reports the synthesis of xanthan gum/titanium dioxide (TiO2 ) nanocomposite for efficient visible light-induced degradation of highly toxic methyl orange dye. Synthesized xanthan gum/titanium dioxide nanocomposite showed good photocatalytic activity due to its high surface area, high light absorption ability and low energy potential between valence and conduction band. Tauc plot studies revealed the band gap of 2.8 eV for fabricated xanthan gum/titanium dioxide nanocomposite denoting its semiconductor nature...
October 15, 2018: International Journal of Biological Macromolecules
Kamal Kumar Paul, P K Giri
Shape tailored TiO₂ nanostructures with various dimensionality (zero to three dimension) have unique physicochemical and functional properties that facilitates its efficient energy and environment applications, e.g., solar light driven photocatalytic hydrogen generation and decontamination of organic/inorganic toxic pollutants, CO₂ reduction into the hydrocarbon fuels, solar cells, supercapacitors and lithium-ion batteries etc. However, the wide band gap nature and the fast recombination of the photogenerated charge carriers in TiO₂ usually limit its overall performance under solar light illumination...
January 1, 2019: Journal of Nanoscience and Nanotechnology
Xiaolin Cai, Zhili Zhu, Weiyang Yu, Chunyao Niu, Jianjun Wang, Baoji Wang, Xiaohua Li, Liwei Zhang, Ruiqi Zhao, Yu Jia
On the basis of density functional theory (DFT) calculations, we propose a stable two-dimensional (2D) monolayer phosphorus carbide (PC) with a GaSe-like structure, which has intriguing electronic and optical properties. Our calculated results show that this 2D monolayer structure is more stable than the other allotropes predicted by Tománek et al. [ Nano Lett., 2016, 16, 3247⁻3252 ]. More importantly, this structure exhibits superb optical absorption, which can be mainly attributed to its direct band gap of 2...
October 11, 2018: Materials
Hao Zhong, Nasir Ilyas, Yuhao Song, Wei Li, Yadong Jiang
Silicon is widely used in semiconductor industry but has poor performance in near-infrared photoelectronic devices because of its high reflectance and band gap limit. In this study, two-step process, deep reactive ion etching (DRIE) method combined with plasma immersion ion implantation (PIII), are used to fabricate microstructured black silicon on the surface of C-Si. These improved surfaces doped with sulfur elements realize a narrower band gap and an enhancement of light absorptance, especially in the near-infrared range (800 to 2000 nm)...
October 10, 2018: Nanoscale Research Letters
Ana Rovisco, Rita Branquinho, Jorge Martins, Maria João Oliveira, Daniela Nunes, Elvira Fortunato, Rodrigo Martins, Pedro Barquinha
Semiconductor nanowires are mostly processed by complex, expensive, and high temperature methods. In this work, with the intent of developing zinc tin oxide nanowires (ZTO NWs) by low-cost and low-complexity processes, we show a detailed study on the influence of chemical parameters in the hydrothermal synthesis of ZTO nanostructures at temperatures of only 200 °C. Two different zinc precursors, the ratio between zinc and tin precursors, and the concentration of the surfactant agent and of the mineralizer were studied...
August 24, 2018: ACS applied nano materials
Dheeraj Mondal, Biplab Kumar Paul, Santanu Das, Debopriya Bhattacharya, Debopriyo Ghoshal, Papiya Nandy, Kaustuv Das, Sukhen Das
Because of the superior optical and electrical properties, copper impregnated size tuneable high-temperature stable manganese dioxide semiconductor quantum dots (SQDs) have been successfully synthesized by a modified chemical synthesis technique. Their size-dependent dielectric properties, semiconducting properties, and current-voltage (I-V) characteristics have been investigated. X-ray diffraction pattern and Raman spectra (RS) confirmed that the required phase is present. Due to the different sintering temperature tuneable size of SQDs has been found and confirmed by high resolution transmission electron microscopy (HRTEM)...
October 5, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Marko Mladenović, Nenad Vukmirović
The effects of thermal disorder on the electronic properties of organic/inorganic halide perovskites were investigated using ab initio molecular dynamics simulations. It was generally found that band gap variations due to effects of thermal disorder are the largest in materials with the smallest lattice constant. The factors that may lead to departure from this trend include the degree of rotational and translational motion of the organic cation and the strength of its dipole. It was found that the contribution of the flexible organic part to the band gap variations is considerably smaller than the contribution of the inorganic part of the material...
October 17, 2018: Physical Chemistry Chemical Physics: PCCP
Izuru Karimata, Kaoru Ohta, Yasuhiro Kobori, Takashi Tachikawa
Partial halide substitution in organolead halide perovskites MAPbX3 (MA = CH3 NH3 + , X = Cl- , Br- , or I- ) leads to semiconductor heterostructures with precisely tuned band-gap energies, which facilitates efficient charge extraction or separation for high-performance solar cells and optoelectronic devices. In this study, partially iodide-substituted MAPbBr3 perovskites were prepared through a halide-exchange reaction in the liquid phase, and in-situ space and time-resolved photoluminescence (PL) profiles were acquired by means of confocal microscopy...
October 2, 2018: ACS Applied Materials & Interfaces
Shenglong Chu, Shusheng Pan, Guanghai Li
CsPbCl3 is a promising material to construct future short wavelength optoelectronic devices based on inorganic perovskite semiconductors. In this study, CsPbCl3 microcrystals were synthesized by a solution phase process. It was found that the photoluminescence (PL) intensities of the CsPbCl3 microcrystals can increase by up to five times under persistent irradiation of UV light without peak shifting, accompanied with an increased absorption coefficient above the band gap and decreased PL lifetime. This PL enhancement is a reversible process with excitation light switching on and off...
October 10, 2018: Physical Chemistry Chemical Physics: PCCP
Zongyou Yin, Moshe Tordjman, Youngtack Lee, Alon Vardi, Rafi Kalish, Jesús A Del Alamo
High electron affinity transition-metal oxides (TMOs) have gained a central role in two-dimensional (2D) electronics by enabling unprecedented surface charge doping efficiency in numerous exotic 2D solid-state semiconductors. Among them, diamond-based 2D electronics are entering a new era by using TMOs as surface acceptors instead of previous molecular-like unstable acceptors. Similarly, surface-doped diamond with TMOs has recently yielded record sheet hole concentrations (2 × 1014 cm-2 ) and launched the quest for its implementation in microelectronic devices...
September 2018: Science Advances
Hiroshi Sugimoto, Masataka Yamamura, Riku Fujii, Minoru Fujii
Shallow impurity doping is an efficient route to tailor optical and electronic features of semiconductor quantum dots (QDs). However, the effect of doping is often smeared by the size, shape, and composition inhomogeneities. In this paper, we study optical properties of almost monodispersed spherical silicon (Si) QDs that are heavily doped with boron (B) and phosphorus (P). The narrow size distribution achieved by a size-separation process enables us to extract doping-induced phenomena clearly. The degree of doping-induced shrinkage of the optical band gap is obtained in a wide size range...
October 2, 2018: Nano Letters
Ming Jiang, Haiyan Xiao, Shuming Peng, Liang Qiao, Guixia Yang, Zijiang Liu, Xiaotao Zu
Advanced semiconductor superlattices play important roles in critical future high-tech applications such as aerospace, high-energy physics, gravitational wave detection, astronomy, and nuclear related areas. Under such extreme conditions like high irradiative environments, these semiconductor superlattices tend to generate various defects that ultimately may result in the failure of the devices. However, in the superlattice like GaAs/AlAs, the phase stability and impact on the device performance of point defects are still not clear up to date...
September 26, 2018: Nanoscale Research Letters
Xiao-Huan Li, Bao-Ji Wang, Xiao-Lin Cai, Wei-Yang Yu, Ying-Ying Zhu, Feng-Yun Li, Rui-Xia Fan, Yan-Song Zhang, San-Huang Ke
Recently, GaTe and C2 N monolayers have been successfully synthesized and show fascinating electronic and optical properties. Such hybrid of GaTe with C2 N may induce new novel physical properties. In this work, we perform ab initio simulations on the structural, electronic, and optical properties of the GaTe/C2 N van der Waals (vdW) heterostructure. Our calculations show that the GaTe/C2 N vdW heterostructure is an indirect-gap semiconductor with type-II band alignment, facilitating an effective separation of photogenerated carriers...
September 26, 2018: Nanoscale Research Letters
Tao Wang, Xinqiang Wang, Zhaoying Chen, Xiaoxiao Sun, Ping Wang, Xiantong Zheng, Xin Rong, Liuyun Yang, Weiwei Guo, Ding Wang, Jianpeng Cheng, Xi Lin, Peng Li, Jun Li, Xin He, Qiang Zhang, Mo Li, Jian Zhang, Xuelin Yang, Fujun Xu, Weikun Ge, Xixiang Zhang, Bo Shen
Due to the intrinsic spontaneous and piezoelectric polarization effect, III-nitride semiconductor heterostructures are promising candidates for generating 2D electron gas (2DEG) system. Among III-nitrides, InN is predicted to be the best conductive-channel material because its electrons have the smallest effective mass and it exhibits large band offsets at the heterointerface of GaN/InN or AlN/InN. Until now, that prediction has remained theoretical, due to a giant gap between the optimal growth windows of InN and GaN, and the difficult epitaxial growth of InN in general...
September 2018: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
P T T Le, K Mirabbaszadeh, M Davoudiniya, M Yarmohammadi
In this paper, we analytically investigate the electronic density of states (DOS) of bilayer Bernal black phosphorus (BBP) in order to study the anisotropic electronic phase transition. We employ the Green's function approach, the Born approximation, and the tight-binding Hamiltonian model including ten intra-layer and four inter-layer hopping energies. BBP consisting of two coupled layers of black phosphorus is a suitable candidate for studying the layer-dependent electronic properties of few-layer black phosphorus...
October 3, 2018: Physical Chemistry Chemical Physics: PCCP
Carlos Alberto Huerta-Aguilar, Viviana Palos-Barba, Pandiyan Thangarasu, Ranjit T Koodali
In this paper, we report the combination of two metal oxides (TiO2 ZnO) that allows mixed density of states to reduce band gap energy, facilitating the photo-oxidation of Congo red dye under visible light. For the oxidation, a possible mechanism is proposed after analyzing the intermediates by GC-MS, and it is consistent with Density Functional Theory (DFT). The nanohybrids were characterized comprehensibly by several analytical techniques such as X-Ray diffraction (XRD), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), and X-ray Photoelectron Spectroscopy (XPS)...
December 2018: Chemosphere
Can Yang, Wei Huang, Lucas Caire da Silva, Kai A I Zhang, Xinchen Wang
The reduction of CO2 with visible light is a highly sustainable method for producing valuable chemicals. The function-led design of organic conjugated semiconductors with more chemical variety than that of inorganic semiconductors has emerged as a method for achieving carbon photofixation chemistry. Here, we report the molecular engineering of triazine-based conjugated microporous polymers to capture, activate and reduce CO2 to CO with visible light. The optical band gap of the CMPs is engineered by varying the organic electron-withdrawing (benzothiadiazole) and electron-donating units (thiophene) on the skeleton of the triazine rings while creating organic Donor-Acceptor junctions to promote the charge separation...
September 22, 2018: Chemistry: a European Journal
Bowen Shi, Yangyang Wang, Jingzhen Li, Xiuying Zhang, Jiahuan Yan, Shiqi Liu, Jie Yang, Yuanyuan Pan, Han Zhang, Jinbo Yang, Feng Pan, Jing Lu
Owing to their few lateral dangling bonds and enhanced gate electrostatics, two-dimensional semiconductors have attracted much attention for the fabrication of channels in next-generation field-effect transistors (FETs). Herein, combining first-principle band structure calculations with more precise quantum transport simulations, we systematically explore the interface properties between monolayer (ML) indium selenide (InSe) and a sequence of common electrodes in an FET. The ML InSe band structure is damaged by Sc, Au, Cr, Pt, and Pd electrodes but identifiable in contact with Ag, Cu, In, graphene and ML O-terminated Cr2C electrodes...
October 3, 2018: Physical Chemistry Chemical Physics: PCCP
Wenzhou Chen, Xianhua Hou, Xingqiang Shi, Hui Pan
The fast development of high-performance devices for diverse applications requires nanoscale materials with multifunctional properties, motivating theoretical exploration into novel two-dimensional (2D) materials. In this work, we propose a new family of 2D nanomaterials, Janus transition metal oxides and chalcogenides MXY (M = Ti, Zr, or Hf; X = S or Se; Y = O or S; X ≠ Y) monolayers, for their versatile applications. We find that the Janus MXY monolayers are semiconductors with a wide range of band gaps ranging from 0...
October 4, 2018: ACS Applied Materials & Interfaces
Kranthi Kumar Gangu, Suresh Maddila, Sreekantha B Jonnalagadda
Many technologies were explored to eliminate the harmful pollutants entering water systems and to minimize their impact on environment. In general, photo-catalysis is one of the sustainable techniques with wider applications and semiconductors in particular were efficiently utilized in the photocatalytic degradation of pollutants. Semiconducting materials, such as TiO2 , ZnO, BiO, CdS, and Ag3 PO4 are frequently used as photo-catalysts due to their suggestible band gap and structural properties. The generation of reactive oxygen species such as hydroxyl and superoxide radicals is the crucial factor in degradation of pollutant molecules...
January 1, 2019: Science of the Total Environment
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