ORCID Profile
0000-0003-0860-600X
Current Organisations
Utrecht University
,
Universiteit Utrecht
,
Ministero dell’Istruzione, dell’Università e della Ricerca
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Publisher: American Chemical Society (ACS)
Date: 28-07-2011
DOI: 10.1021/NL202051W
Abstract: One of the main motivations for the great interest in semiconductor nanowires is the possibility of easily growing advanced heterostructures that might be difficult or even impossible to achieve in thin films. For III-V semiconductor nanowires, axial heterostructures with an interchange of the group III element typically grow straight in only one interface direction. In the case of InAs-GaAs heterostructures, straight nanowire growth has been demonstrated for growth of GaAs on top of InAs, but so far never in the other direction. In this article, we demonstrate the growth of straight axial heterostructures of InAs on top of GaAs. The heterostructure interface is sharp and we observe a dependence on growth parameters closely related to crystal structure as well as a diameter dependence on straight nanowire growth. The results are discussed by means of accurate first principles calculations of the interfacial energies. In addition, the role of the gold seed particle, the effect of its composition at different stages during growth, and its size are discussed in relation to the results observed.
Publisher: American Chemical Society (ACS)
Date: 12-03-2008
DOI: 10.1021/NL072713M
Abstract: We first describe the synthesis of novel and highly porous boron nitride (BN) nanospheres (100-400 nm o.d.) that exhibit a rough surface consisting of open BN nanocones and corrugated BN ribbons. The material was produced by reacting B2O3 with nanoporous carbon spheres under nitrogen at ca. 1750 degrees C. The BN nanospheres were characterized using scanning electron microscopy, high-resolution electron microscopy, and electron energy loss spectroscopy. The porous BN spheres show relatively large surface areas of ca. 290 m2/g and exhibit surprisingly stable field emission properties at low turn-on voltages (e.g., 1-1.3 V/microm). We attribute these outstanding electron emission properties to the presence of finite BN ribbons located at the surface of the nanospheres (exhibiting zigzag edges), which behave like metals as confirmed by first-principles calculations. In addition, our ab initio theoretical results indicate that the work function associated to these zigzag BN ribbons is 1.3 eV lower when compared with BN-bulk material.
Publisher: IOP Publishing
Date: 26-08-2009
DOI: 10.1088/0957-4484/20/37/375501
Abstract: Carbon nanotube surfaces, activated and randomly decorated with metal nanoclusters, have been studied in uniquely combined theoretical and experimental approaches as prototypes for molecular recognition. The key concept is to shape metallic clusters that donate or accept a fractional charge upon adsorption of a target molecule, and modify the electron transport in the nanotube. The present work focuses on a simple system, carbon nanotubes with gold clusters. The nature of the gold-nanotube interaction is studied using first-principles techniques. The numerical simulations predict the binding and diffusion energies of gold atoms at the tube surface, including realistic atomic models for defects potentially present at the nanotube surface. The atomic structure of the gold nanoclusters and their effect on the intrinsic electronic quantum transport properties of the nanotube are also predicted. Experimentally, multi-wall CNTs are decorated with gold clusters using (1) vacuum evaporation, after activation with an RF oxygen plasma and (2) colloid solution injected into an RF atmospheric plasma the hybrid systems are accurately characterized using XPS and TEM techniques. The response of gas sensors based on these nano(2)hybrids is quantified for the detection of toxic species like NO(2), CO, C(2)H(5)OH and C(2)H(4).
Location: No location found
Location: Italy
No related grants have been discovered for Zeila Zanolli.