Understanding crystal growth and electronic properties of semiconductor nanowires and nanostructures

我的研究计划的重点是在半导体纳米线材料和应用的快速新兴领域。在半导体器件中朝着增加的功能和性能的持续进展将需要制造其中电子在多于一个维度上被高度限制的结构的能力。在将半导体纳米线结合到有用的应用中之前，有几个关键问题需要解决，即：1）如何控制无缺陷纳米线沿沿着线的长度以及沿径向的生长，以便形成用于特定器件应用的各种“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族半导体材料，这些材料将被开发成量子计算、红外传感和太阳能应用的原型器件。原型p-n结结构将通过金属有机气相外延（MOVPE）制造，并将使用扫描电子显微镜内的纳米探针研究其电性能。该提案的一个重要部分将涉及将我们最近在这一领域的进展扩展到氧化锌，这是一种在可见光和紫外光发光器件方面具有巨大潜力的材料。尽管在这种材料上进行了十多年的密集努力，但仍然存在许多重要的问题，例如：1）无催化剂纳米线生长背后的物理机制是什么; 2）残余n型导电性的根本原因是什么;以及3）观察到的p型掺杂的机制是什么？我们将利用我们的MOVPE工艺生长的纳米线的高结晶质量，以及我们在半导体掺杂，光谱学和原位电学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发展，这将为加拿大的半导体行业带来好处，例如在先进的照明技术，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.