Synthesis of GaS Nanoparticles from a Single-Source Precursor [Ga(S 2 CNEt 2 ) 3 /

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Synthesis of GaS Nanoparticles from a Single-Source Precursor [Ga(S2CNEt2)3] Mohammad Azad Malika, Paul O`Briena, Sibusiso N. Mlondob, Neerish Revaprasadu,b a

School of Chemistry and School of Materials, The University of Manchester, Oxford Road, Manchester M13 9PL, UK, e-mail: [email protected], [email protected] b

Department of Chemistry, University of Zululand, Private Bag X1001, Kwadlangezwa, 3886, Kwazulu-Natal Province, South Africa.

ABSTRACT GaS nanoparticles have been synthesized by thermolysis of [Ga(S2CNEt2)3] in 4ethylpyridine. Their absorption spectrum give a band edge at 440 nm (band gap,3.0 eV). XRD pattern showed abroad peaks corresponding to cubic phase of GaS. TEM images confirmed the crystalline nature of particles with narrow size distribution (5.4 nm ± 0.7 dia). To our knowledge this the first time that GaS nanoparticles have been prepared. INTRODUCTION GaS is a mid band gap semiconductor material. Thin films of GaS have electrical, optical, and photovoltaic properties suitable for use in various optoelectronic devices [1]. It has been used in passivating the surface of III/V materials [2]. A considerable amount of work has been published on the synthesis of single-molecule precursors for the deposition of III/V [3-5] or II/VI [6-10] semiconducting materials; however, only a handful of reports are available on the preparation of III/VI [11-20] materials from such precursors. In a series of papers we have developed the chemistry of mixed alkyydithio or diseleno carbamates of group 12 metals and demonstrated that these compounds can be used as precursors for the deposition of II/VI materials. Similarly InS and GaS thin films has been deposited by MOCVD method using alky(dialkyldithio-carbamato)indium(III) or alky(dialkyldithio-carbamato)gallium(III) as single source precursors. The deposition of gallium sulfide from the parent tris(diethyldithiocarbamato)gallium(III) was in general less successful whereas the mixed alkyl complex [Me2GaS2CNEt2] gave thin, crystalline films of gallium sulfide on GaAs(100) with a crystallite sizes of ca 100 nm . Other single source precursors used for the deposition of III/VI materials include Me2InSePh [11], In(SePh)3 [11] nBuIn(S iPr)2 [13,14], [In2Se21] [14], [iBu21nS nPr] [14], cubane [(tBu)GaS]4 [12] and [(tBu)21n(StBu)2 [18]. All these reports deal with the use of single source precursors to grow thin films. There has been even fewer reports on the synthesis of III-VI nanomaterials [21-29]. Dimitirjevic and Kamat prepared colloids of In2Se3 with particle sizes of approximately 2-3 nm (SMP stabilized) and 30 nm (PVA stabilized) with absorption maxima at 375 and 250 nm (SMP stabilized) and an onset of absorption at approximately 550 nm (PVA stabilized) [30]. They also reported the synthesis of In2S3 colloids in acetonitrile, with


particle diameters ranging between between 100 and 200 nm [31]. Barron et al. [32] reported the preparation of nanoparticles of GaSe and InSe by MOCVD using the cubane precursors [(tBu)GaSe]4 and [(EtMe2C)InS

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