Terahertz Spectroscopy of Semiconductor Nanowires

碳纳米管和氧化锌纳米颗粒等纳米结构已经被用于轮胎和防晒霜等商业产品。然而，尽管在了解纳米材料的机械和光学性质方面取得了进展，我们仍然处于纳米光电子学和纳米光子学领域的初级阶段。因此，今天对这些纳米材料的基础材料科学的了解取得的进展将对未来30年的广泛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学特性的复杂性。传统上，新材料和器件的测试是通过电传输测量来进行的。不幸的是，在直径30 nm的纳米线或负极颗粒上进行电接触是极其困难的。事实上，即使进行了接触，也很难将无氧材料的性质与接触的性质分开。此外，这样的测量还受到重复性问题的困扰。因此，迫切需要能够快速、可靠地提取纳米结构材料的电学性质的技术。这种技术的出现将极大地加速新材料的发展，并使基于这些材料的器件很快推向市场。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，并通过开发精确的模型来从测量数据中提取最重要的器件特有的电学性质。我们所获得的知识将有助于我们开发基于半导体纳米线的新型光电子器件。

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.