Germanium Nanocrystals Synthesized in High-Boiling-Point Organic Solvents

Ge nanoparticles with sizes from 1 to 15 nm were synthesized by thermal decomposition of the germane precursors trichlorogermane, tetraethylgermane, and tetrabutylgermane. Experiments were performed in the organic solvents trioctylamine, squalene, and octacosane, which have boiling points in the temperature range from 380 to 429 °C. The use of high-boiling-point solvents extended the temperature range of the reactions, thus enabling the experiments to be conducted with organogermane precursors which have high decomposition points above 400 °C. Characterization by X-ray diffraction and transmission electron microscopy showed that, depending on the reaction temperature, the final decomposition products consist of amorphous Ge nanoparticles, nanocrystals, or nanowires that grow only in the 〈110〉 direction.