Germanium nanocrystals may be of interest for a variety of electronic and optoelectronic applications including photovoltaics, primarily due to the tunability of their band gap from the infrared into the visible range of the spectrum. This letter discusses the synthesis of monodisperse germanium nanocrystals via a nonthermal plasma approach which allows for precise control of the nanocrystal size. Germanium crystals are synthesized from germanium tetrachloride and hydrogen entrained in an argon background gas. The crystal size can be varied between 4 and 50 nm by changing the residence times of crystals in the plasma between ∼30 and 440 ms. Adjusting the plasma power enables one to synthesize fully amorphous or fully crystalline particles with otherwise similar properties.
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This work was supported primarily by the MRSEC Program of the National Science Foundation under Award No. DMR-0212302 and by the Initiative for Renewable Energy and the Environment under Grant No. LG-C5-2005. Partial support was also provided by NSF-IGERT Grant No. DGE-0114372.