Terahertz Spectroscopy of Semiconductor Nanowires

纳米结构如碳纳米管和氧化锌纳米颗粒已经被用于商业产品如轮胎和防晒霜。然而，尽管在理解纳米材料的机械和光学性质方面取得了进展，但我们仍然处于纳米光电子学和纳米光子学领域的黎明。因此，在理解这些纳米材料的基础材料科学方面取得的进展将在未来30年内对广泛的商业产品产生重大影响。开发纳米光电子元件的困难之一是测量其电特性的复杂性。传统上，新材料和新器件的测试都是通过电输运测量来进行的，但不幸的是，在直径为30 nm的纳米线或纳米颗粒上进行电接触是非常困难的。实际上，即使制造了接触，也难以将纳米材料的性质与接触的性质分开。此外，这样的测量受到可重复性问题的困扰。因此，迫切需要能够快速可靠地提取纳米结构材料电特性的技术.这些技术的可用性将大大加速新材料的开发，并允许基于这些材料的器件更快地推向市场。我们建议通过将光泵太赫兹探测光谱（OPTPS）技术应用于半导体纳米线来解决这些问题，并通过开发精细的模型来从测量数据中提取最重要的器件特定的电学特性。我们获得的知识将帮助我们开发基于半导体纳米线的新型光电器件。

Nanostructures such as carbon nanotubes and ZnO nano-particles are already being used in commercialproducts such as tyres and sunscreens. However, despite progress in understanding the mechanical andoptical properties of nano-materials we are still at the dawn of the fields of nano-optoelectronics andnano-photonics. Advances in understanding the fundamental materials science of these nano-materials todaywill therefore have a major impact on a wide range of commercial products over the next 30 years. One of thedifficulties with developing nano-optoelectronic components is the complexity of measuring their electricalproperties. Traditionally, new materials and devices have been tested via electrical transport measurements.Unfortunately, it is extremely difficult to make electrical contacts on a 30nm diameter nano-wire or anano-particle. Indeed even if the contacts are made it is then difficult to separate the properties of thenano-material from those of the contact. Additionally, such measurements are plagued by reproducibilityproblems. Thus there is a pressing need for techniques that can quickly and reliably extract the electricalproperties of nano-structured materials. The availability of such techniques would greatly accelerate thedevelopment of new materials and allow devices based on these materials to be brought to the market sooner.We propose to solve these problems by applying the technique of optical pump terahertz probe spectroscopy(OPTPS) to semiconductor nano-wires, and by developing refined models to extract the most importantdevice-specific electrical properties from the measured data. The knowledge we gain will help us develop newoptoelectronic devices based on semiconductor nano-wires.