Synthesis of Monolayer-Capped GaAs Nanopartides
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Synthesis of Monolayer-Capped GaAs Nanoparticles Jin Luo a), Lingyan Wang a), Li Han a), Mathew M. Maye a), Jian Q. Wang b), Eric I. Altman c), and Chuan-Jian Zhong a)* a)
Department of Chemistry, State University of New York (SUNY) at Binghamton, Binghamton, New York 13902. b)Department of Physics, SUNY-Binghamton; c) Department of Chemical Engineering, Yale University, New Haven, CT 06520 * To whom correspondence should be addressed ([email protected]) ABSTRACT This paper reports the preliminary results of an investigation of the synthesis of monolayer-capped GaAs nanoparticles using different surface capping molecules. Our approach focuses on the surface encapsulation using alkanethiolates. The organic shell can effectively block the aggregation during nanoparticle synthesis, providing molecularlevel control of the core-shell structure. The results have demonstrated the effect of surface alkanethiolate modification on the interparticle spatial properties and particle sizes, which upon further refinement could lead to the ability in controlling the size of GaAs nanoparticles.
INTRODUCTION The fabrication of nanocrystal semiconductors with well defined sizes and shapes are increasingly important in quantum computation and optoelectronic devices [1-2]. The synthesis of gallium arsenide and gallium phosphide nanocrystalline materials has been reported using a solution-phase synthesis [3], which often led to a wide range of particle size distributions. In an early report, gallium arsenide (GaAs) nanoparticles have been prepared from reaction of GaCl3 and As(NMe2)3 in 4-ethylpyridine [4]. In another report, GaAs nanocrystals with sizes in the range of 7 to 15 nm have been synthesized by an electrochemical route from the acidic solutions of metallic gallium and arsenic oxide [5]. GaAs nanoparticles were also grown using a single source organometallic precursor [6]. The major problem in the previous studies is the lack of the ability to control the size. We have recently explored several modified synthetic protocols for the synthesis of GaAs nanoparticles using different surface capping molecules. This study was an expansion of our earlier work in controlling the size and shape of metal and alloy nanoparticles by introducing capping agents [7-9]. The organic capping shell can effectively block the aggregation during nanoparticle synthesis, providing a molecularlevel control of the nanoparticles. Our approach focused on the surface encapsulation using alkanethiolates on the surface of GaAs [10]. While there are a number of synthetic parameters to be further refined to improve the synthetic and processing routes for the production of monodispersed GaAs nanoparticles, we report herein the preliminary results.
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EXPERIMENTAL Chemicals. Gallium (III) chloride (GaCl, 99.999%, Anhydrous), soliumpotassium alloy (Na-K, 44 wt % Na, 56 wt % K), arsenic powder (99.999+%), 2methoxyethyl ether (diglyme, 99.5%, anhydrous), 1-octadecanethiol (ODT, 98%) and triethylamine (99.5%) were purchased from Aldrich and us
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