Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA.
ACS Nano. 2013 Feb 26;7(2):1731-9. doi: 10.1021/nn305833u. Epub 2013 Jan 28.
We report the growth, structural, and electrical characterization of single-crystalline iron pyrite (FeS₂) nanorods, nanobelts, and nanoplates synthesized via sulfidation reaction with iron dichloride (FeCl₂) and iron dibromide (FeBr₂). The as-synthesized products were confirmed to be single-crystal phase pure cubic iron pyrite using powder X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. An intermediate reaction temperature of 425 °C or a high sulfur vapor pressure under high temperatures was found to be critical for the formation of phase pure pyrite. Field effect transport measurements showed that these pyrite nanostructures appear to behave as a moderately p-doped semiconductor with an average resistivity of 2.19 ± 1.21 Ω·cm, an improved hole mobility of 0.2 cm² V⁻¹ s⁻¹, and a lower carrier concentration on the order of 10¹⁸-10¹⁹ cm⁻³ compared with previous reported pyrite nanowires. Temperature-dependent electrical transport measurements reveal Mott variable range hopping transport in the temperature range 40-220 K and transport via thermal activation of carriers with an activation energy of 100 meV above room temperature (300-400 K). Most importantly, the transport properties of the pyrite nanodevices do not change if highly pure (99.999%) precursors are utilized, suggesting that the electrical transport is dominated by intrinsic defects in pyrite. These single-crystal pyrite nanostructures are nice platforms to further study the carrier conduction mechanisms, semiconductor defect physics, and surface properties in depth, toward improving the physical properties of pyrite for efficient solar energy conversion.
我们报告了通过铁的二氯化物（FeCl₂）和二溴化铁（FeBr₂）的硫化反应合成的单晶黄铁矿（FeS₂）纳米棒、纳米带和纳米板的生长、结构和电学特性。使用粉末 X 射线衍射、拉曼光谱和透射电子显微镜证实所合成的产物为单相纯立方黄铁矿。发现中间反应温度为 425°C 或高温下的高硫蒸气压对于形成单相黄铁矿是至关重要的。场效应输运测量表明，这些黄铁矿纳米结构似乎表现为适度 p 型掺杂半导体，平均电阻率为 2.19±1.21Ω·cm，空穴迁移率提高到 0.2cm²V⁻¹s⁻¹，载流子浓度约为 10¹⁸-10¹⁹cm⁻³，与之前报道的黄铁矿纳米线相比有所降低。温度依赖的输运测量表明，在 40-220K 的温度范围内存在莫特变程跳跃输运，在室温（300-400K）以上通过载流子的热激活进行输运，激活能为 100meV。最重要的是，如果使用高纯度（99.999%）的前体，黄铁矿纳米器件的输运性质不会改变，这表明输运主要由黄铁矿中的本征缺陷控制。这些单晶黄铁矿纳米结构是进一步研究载流子传导机制、半导体缺陷物理和表面性质的理想平台，有助于提高黄铁矿的物理性质，以实现高效的太阳能转换。
