Nonthermal plasma synthesis of metal sulfide nanocrystals from metalorganic vapor and elemental sulfur
Nonthermal plasma synthesis of metal sulfide nanocrystals from metalorganic vapor and elemental sulfur
复制标题
金属有机蒸气和单质硫非热等离子体合成金属硫化物纳米晶
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
E. Aydil
中科院分区：
文献类型：
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作者：
E. Thimsen;U. Kortshagen;E. Aydil
在低温等离子体中合成纳米晶体一直是人们关注的第四族元素半导体材料，如Si和Ge。相比之下，人们对等离子体合成化合物纳米晶知之甚少，将这种合成方法扩展到由两种或两种以上元素组成的纳米晶的时机已经成熟，如金属硫化物、氧化物和氮化物。为此，我们研究了金属有机前驱体二乙基锌(II)、六氟乙酰丙酮铜(I)乙烯基三甲基硅烷和四(二甲氨基)锡(IV)在Ar-硫等离子体中分别合成了ZnS、Cu2S和SnS纳米晶。用原位光学发射光谱观察了合成过程中各种等离子体物种相对浓度的变化，用非原位材料表征了这些纳米晶的晶体结构、元素组成和光吸收。在金属有机蒸气进料速率不变的情况下，在一个较小的阈值以上，纳米晶的元素组成与进入等离子体的硫流量无关。在硫磺流量不变的情况下，纳米晶的组成依赖于金属有机气体的进料速度。具体地说，随着金属有机蒸气流速的增加，纳米晶中的金属原子分数增加，从而产生更多的富金属晶相。金属有机进料速度可以用来控制用这种等离子体工艺合成的金属硫化物纳米晶的组成和晶相。
Nanocrystal synthesis in nonthermal plasmas has been focused on elemental group IV semiconductors such as Si and Ge. In contrast, very little is known about plasma synthesis of compound nanocrystals and the time is ripe to extend this synthesis approach to nanocrystals comprised of two or more elements such as metal sulfides, oxides and nitrides. Towards this end, we studied, in an argon–sulfur plasma, the synthesis of ZnS, Cu2S and SnS nanocrystals from metalorganic precursors diethyl Zn(II), hexafluoroacetylacetonate Cu(I) vinyltrimethylsilane, and tetrakis(dimethylamido) Sn(IV), respectively. In situ optical emission spectroscopy was used to observe changes in relative concentrations of various plasma species during synthesis, while ex situ material characterization was used to examine the crystal structure, elemental composition and optical absorption of these nanocrystals. For a constant metalorganic vapor feed rate, the elemental composition of the nanocrystals was found to be independent of the sulfur flow rate into the plasma, above a small threshold value. At constant sulfur flow rate, the nanocrystal composition depended on the metalorganic vapor feed rate. Specifically, the ensemble metal atomic fraction in the nanocrystals was found to increase with increasing metalorganic vapor flow rates, resulting in more metal-rich crystal phases. The metalorganic feed rate can be used to control the composition and crystal phase of the metal-sulfide nanocrystals synthesized using this plasma process.