Understanding crystal growth and electronic properties of semiconductor nanowires and nanostructures

我的研究计划的重点是迅速崛起的半导体纳米线材料和应用领域。在提高半导体器件的功能和性能方面的持续进展将需要能够制造其中电子在不止一个维度上高度受限的结构。在半导体纳米线可以被纳入到有用的应用之前，有几个关键问题需要解决，即：1)如何控制无缺陷纳米线的沿导线长度和径向的生长，以便为特定的器件应用形成各种“核-壳”结构；2)如何测量这些非常小的结构中的电导率；以及3)如何通过掺杂来控制电导率。我们将针对某些特定的材料组合来解决这些问题，例如III-V半导体材料，这些材料将被开发成应用于量子计算、红外传感和太阳能的原型器件。将利用金属有机气相外延(MOVPE)技术制作p-n结的原型结构，并使用扫描电子显微镜内的纳米探针研究其电学性质。该提案的一个重要部分将涉及将我们在这一领域的最新进展扩展到氧化锌，这是一种在可见光和紫外线下具有巨大潜力的发光设备材料。尽管对这种材料进行了十多年的激烈研究，但许多重要的问题仍然存在，例如：1)无催化剂纳米线生长背后的物理机制；2)残留n型电导率的根本原因；以及3)观察到的p掺杂的机制是什么？我们将利用我们的MOVPE工艺生长的高结晶质量的纳米线，以及我们在半导体掺杂、光学光谱和现场电子测量方面的专业知识来解决这些问题。从这项研究中获得的结果将导致设备应用的开发，这些应用将为加拿大的半导体行业带来好处，例如在先进照明技术、电信和太阳能领域。

The focus of my research program is in the rapidly emerging area of semiconductor nanowire materials and applications. Continued progress towards increased functionality and performance in semiconductor devices will require the ability to fabricate structures in which electrons are highly confined in more than one dimension. There are several key issues to be addressed before semiconductor nanowires can be incorporated into useful applications, namely: 1) how to control the growth of defect free nanowires both along the length of the wire, as well as in the radial direction, in order to form various "core-shell" structures for specific device applications; 2) how to measure the electrical conductivity in these very small structures; and 3) how to control the electrical conductivity by means of doping. We will address these questions for certain specific materials combinations, such as III-V semiconductor materials, which will be developed into prototype devices with applications in quantum computing, infrared sensing, and solar energy. Prototype p-n junction structures will be fabricated by metalorganic vapour phase epitaxy (MOVPE) and their electrical properties will be studied using a nanoprobe inside a scanning electron microscope. A significant portion of the proposal will involve extending our recent progress in this area to zinc oxide, a material with great potential for light emitting devices in the visible and ultraviolet. Despite more than a decade of intense effort on this material, many important questions remain, such as: 1) what are the physical mechanisms behind catalyst free nanowire growth; 2) what is the underlying cause of the residual n-type conductivity; and 3) what are the mechanisms responsible for the observed p-doping? We will exploit the high crystalline quality of nanowires grown by our MOVPE process, together with our expertise in semiconductor doping, optical spectroscopy, and in situ electrical measurements to address these questions. The results obtained from this research will lead to the development of device applications that will provide benefits to Canada's semiconductor industry, for example in the fields of advanced lighting technologies, telecommunications, and solar energy.