Ultrathin Single‐Crystalline Boron Nanosheets for Enhanced Electro‐Optical Performances

Xu, Junqi; Chang, Yangyang; Gan, Lin; Ma, Ying; Zhai, Tianyou

doi:10.1002/advs.201500023

Cited by 86 publications

(111 citation statements)

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“…Two activation energy values are obtained, E σ1 ≈620 meV and E σ2 ≈27 meV, thus providing solid evident that two thermal activation conduction processes contribute to the conductivity over the temperature range from 83 to 273 K. 35,36 In general, temperature dependence of carrier transport in semiconductor channels may be due to strong phonon scattering, optical or acoustic phonons. 34 The monotone current increase as the temperature increase indicates phonon scattering mechanism is not responsible for the transport behavior in this measurement because strong phonon scattering usually gives rise to the current reduction.…”

confidence: 99%

Veritable electronic characteristics in ZnO nanowire circuits uncovered by the four-terminal method at a low temperature

Zhang

2017

AIP Advances

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Understanding the natural electrical properties in semiconductor channels and the carrier transport across the metal-semiconductor contact is essential to improve the performance of nanowire devices. This work presents the true electronic characteristics of ZnO nanowire devices measured by a four-electrode method at a low-temperature environment. The temperature rise leads to the decrease in near-band-gap emission, which is attributed to two non-radiative recombination processes. For ZnO circuits, thermionic emission carrier transport mechanism plays a dominant role at Ti-Au/ZnO interface and the transport mechanism in ZnO nanowires is governed by two competitive thermal activation conduction processes: optical or acoustic phonons assisting hopping.

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confidence: 99%

Veritable electronic characteristics in ZnO nanowire circuits uncovered by the four-terminal method at a low temperature

Zhang

2017

AIP Advances

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“…Compared to rhombohedral α-B, bulk α-tetragonal B50 was not stable at ambient temperature and pressure, and can only be synthesized at high temperature (1200-1300 ºC) and high pressure (8-9 GPa) [63]. The reason why we are attracted by this system is because more recently, Xu, J., et al, [10] have successfully synthesized ultrathin single-crystalline boron nanosheets. The Raman spectrum and the HRTEM image provide that the structure of these sheets can be attributed to the (002) and (200) lattice planes of α-tetragonal B50 phases [10].…”

Section: Energy Barriersmentioning

confidence: 99%

“…The reason why we are attracted by this system is because more recently, Xu, J., et al, [10] have successfully synthesized ultrathin single-crystalline boron nanosheets. The Raman spectrum and the HRTEM image provide that the structure of these sheets can be attributed to the (002) and (200) lattice planes of α-tetragonal B50 phases [10]. The ultrathin nature of their structure was also confirmed by the almost transparent image of the structure and behaves as a p-type semiconductor with high carrier mobility (see Fig.…”

Section: Energy Barriersmentioning

confidence: 99%

“…Prompted by a recent research on the synthesis of ultrathin boron sheets (i.e., [8][9][10][11][12] nm or 20 layers) containing thin films of α-tetragonal B50, we performed simulations based on the SCED-LCAO method to test the stability of monolayer α-tetragonal B50 sheet. We found this structure to be unable to keep the α-tetragonal B50 symmetry.…”

Section: Band Gap Opening In Patterned Graphene Structures With Holesmentioning

confidence: 99%

“…An ultrathin single-crystalline Boron nanostructure has recently been successfully synthesized [10]. High-resolution TEM and the selected-area electron diffraction pattern have demonstrated that the single-crystalline structure is like a few layered tetragonal α-B50 film.…”

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Materials design and band gap engineering of complex nanostructures using a semi-empirical approach : low dimensional boron nanostructures, h-BN sheet with graphene domains and holey graphene.

Kah¹

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Kah, Cherno Baba, "Materials design and band gap engineering of complex nanostructures using a semi-empirical approach : low dimensional boron nanostructures, h-BN sheet with graphene domains and holey graphene." (2016 calculates the charge distribution around a site self-consistently (SC). Throughout this dissertation, we will refer this semi-empirical Hamiltonian using the acronym SCED-LCAO.Our first application on boron nanostructures using SCED-LCAO revealed that one and two-dimensional nanostructures (referred as α, δ4 and δ6 sheets) based on icosahedral α-B12 clusters were structurally stable. A relative stability with respect to δ6 was also vii determined for the two-dimensional sheets with the strength of the stability in the order of 4 < < 6 . The infinite one-dimensional chain (which is the least stable among the low dimensional Boron structures predicted) as well as δ4 and δ6 sheets are found to have semiconducting properties while α sheet has metallic properties.With recent reports on the synthesis of an ultra-thin layer of α-tetragonal B50 structure, we delved into a second project that focused on investigating the structural stabilities and properties of a single layer of α-tetragonal B50. We found that, the α-tetragonal B50 does not keep its two-dimensional nature but prefers to exhibit symmetry breaking. Our prediction is inconsistent with experimental observations but this may be due to experiments discerning double or multi-layer structures of α-tetragonal B50. We note that the stability of multi-layer α-tetragonal B50 structure requires further investigation.A third application studied includes the band gap engineering on h-BN sheet by creating in it graphene domains of different shapes (triangular, circular, hexagonal and rectangular) and sizes with the aim of reducing the energy gap of pristine h-BN. For this project, the parametrization of the SCED-LCAO Hamiltonian corresponding to the nitrogen element was developed as a first step towards the investigation of pristine h-BN sheets and h-BN sheets embedded with graphene domains. The results of our study of h-BN sheets embedded with graphene domains reveal that the density of states are dependent on the shapes and sizes of the graphene domains and that hexagonal and circular graphene domains are good candidates for engineering the gap of a pristine h-BN sheet.A fourth application of SCED-LCAO method focused on a study of the band gap of holey graphene sheets, i.e., graphene sheets carved with different types of geometrical viii holes. We found holey triangular graphene sheets to have the smallest possible energy gap with its biggest size being the most stable and having 0.11 for gap. Holey circular graphene sheet has also a stable structure with a possible gap of 0.35 while the most stable structure among the holey rectangular sheets was found to have a gap of 0.4 .Computational studies undertaken in this dissertation demonstrate that the SCED-LCAO method is a powerful technique for designing materials with desired properties, which can guid...

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A Fully Transparent and Flexible Ultraviolet–Visible Photodetector Based on Controlled Electrospun ZnO‐CdO Heterojunction Nanofiber Arrays

Zheng

Gan

et al. 2015

Adv Funct Materials

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5885wileyonlinelibrary.com performance for detection in the deep ultraviolet; [ 6 ] ZnO (3.4 eV), SnO 2 (3.6 eV), In 2 O 3 (3.6 eV), and Nb 2 O 5 (3.4 eV) nanowires are sensitive to ultraviolet light [7][8][9][10][11] CdS (2.4 eV), ZnTe (2.4 eV), and In 2 S 3 (2.0 eV) nanowires work well in the visible spectral range and InAs (0.35 eV) and Cd 3 P 2 (0.65 eV) nanowires play a vital roles in near-infrared light detection. [12][13][14][15][16] Interestingly, these days, photodetectors with a broad spectral response have started to attract more and more attention because as such a "multicolor" response can be realized in a single photodetector. [ 17,18 ] Currently, there are two ways to achieve such a response: one is to form an alloy, for instance (Al, In) x Ga (1x ) N, which has a tunable response range from the near-ultraviolet to near-infrared light; [ 19,20 ] another is to form hybrid structures, such as CdSe/ ZnTe core-shell structures, [ 21 ] ZnS/ZnO biaxial structures [ 22 ] or quantum dots/ organic mixtures, [23][24][25] which combine the spectral response range of their constituting components. However, the low stability or complex fabrication requirements prevent the wide spread of such "multicolor" materials. According to the "6S" criteria for evaluating photodetectors, that is, high spectral selectivity, high signal-to-noise ratio, high sensitivity, high stability, high speed, and simplicity for fabrication, the realization of a highly stable, simply processed photodetector is still an issue to be considered. [ 26 ] Electrospinning is a cheap and facile method to fabricate various nanofi bers on a large scale. This has been widely utilized for supercapacitors, lithium-ion batteries, photocatalysis, etc. [ 27,28 ] Specifi cally, the target material is mixed with a polymer fi rst to form a uniform solution, and then the solution is expelled out of the vessel by an ejector jet pump. At the same time, a high voltage is applied between the outlet of the vessel and the collecting substrate, which endows the exposed solution with a charge and provides a strong fi eld to transform the solution into thin nanofi bers of tens to hundreds of nanometers in diameter. Finally, all the nanofi bers are collected on the substrate. It is worth mentioning that the product is generally composed of a huge number of random nanofi bers. In contrast, uniform nanofi ber arrays can be achieved by putting separated electrodes on the substrate during the electrospinning It is essential for novel photodetectors to show good photoresponses, high stability, and have facile fabrication methods. Herein, an optimized electrospinning method to fabricate a photodetector based on nanowire arrays that has a wide spectral response range is demonstrated. Arrays of ZnO-CdO hybrid nanowires are carefully fabricated fusing ZnO and CdO portions into the same nanowires and subsequently assembling those nanowires into a regular structure. Compared to pure ZnO or CdO nanowire arrays, the hybrid arrays show comparable photocurrent/dark current ratios a...

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Ultrathin Single‐Crystalline Boron Nanosheets for Enhanced Electro‐Optical Performances

Cited by 86 publications

References 111 publications

Veritable electronic characteristics in ZnO nanowire circuits uncovered by the four-terminal method at a low temperature

Veritable electronic characteristics in ZnO nanowire circuits uncovered by the four-terminal method at a low temperature

Materials design and band gap engineering of complex nanostructures using a semi-empirical approach : low dimensional boron nanostructures, h-BN sheet with graphene domains and holey graphene.

A Fully Transparent and Flexible Ultraviolet–Visible Photodetector Based on Controlled Electrospun ZnO‐CdO Heterojunction Nanofiber Arrays

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