Investigations on fundamental properties/issues of nanowires/structures with applications in solar cell, energy storage, and sensing devices.

纳米结构可以作为制造许多器件的基本元素。其中，由硅和氧化锌组成的纳米结构--氧化锌，具有显著的物理性能，一直是各种应用领域研究的重点。*硅纳米线除了在电子和光电子方面有许多应用外，还被用来制造新一代可持续能源设备，如太阳能电池。硅纳米线SiNW阵列除了具有优异的光减反射性能外，还提供了独立设计光捕获和载流子收集工艺的机会。*此外，半导体氧化锌在过去几年中一直是许多应用领域的研究重点，因为这种材料无毒，化学稳定，与直接宽带隙、强离子键和激子结合能60 meV具有生物兼容性。*尽管这些纳米结构提供了重要的前景，但与这些元素的物理特性相关的几个挑战性问题仍然存在；例如，在SiNW太阳能电池的情况下，表面和界面复合、表面粗糙度、机械和化学稳定性、表面形态、掺杂控制、与其他模块的集成以及器件封装是其中的一些问题。以氧化锌为例，在许多应用中，均匀分布和高度定向的纳米粒子是至关重要的。此外，p型或n型氧化锌纳米管的可控制备是其在纳米光电子器件中应用的关键，因为p型氧化锌纳米管具有带隙缩小和强受主相关的光致发光，而n型纳米管具有带隙展宽和强烈的施主束缚激子。*因此，为任何大规模和高产量的特定应用准备成本效益和高质量的这些纳米线被认为是一项非常具有挑战性的任务。*这项建议的总体范围是各种应用的硅和氧化锌半导体纳米线/纳米结构阵列的设计、制造和表征。工作将集中在与结构、物理性质、纳米结构的制造以及在光子学、能源和传感器件中的应用有关的基本问题的研究和调查上。所开发技术的低成本被认为是一个重要因素。最后，我们设计和制造了基于这项工作中最有希望的元件的器件；我们的重点将是开发基于本提案中生长的纳米线/结构的气体电离传感器(GIS)和光伏器件。因此，在本方案中，将主要研究以下两个目标：*1)探索低成本、高质量、大批量生长氧化锌和硅纳米线的方法。这些技术应该使我们能够在生长过程中控制这些纳米结构的形态、尺寸、纵横比和导电性。将解决纳米线阵列的掺杂、取向、分布和均匀性等问题。*2)基于第一个目标中描述的所产生的纳米结构来开发器件。将使用氧化锌和硅纳米线设计和制造气体电离传感器和光伏器件。*这项建议将从两个方面对减少我们的环境污染产生重大影响：第一，开发光伏设备来产生清洁和可再生的能源；第二，开发微型地理信息系统来检测污染物气体。

Nanostructures can be used as fundamental elements in manufacturing many devices. Among them, nanostructures made of silicon and zinc oxide, ZnO, with significant physical properties have been the focus of research for a variety applications. *Silicon nanowires, besides having many applications in electronic and optoelectronics, are used to fabricate the new generation of sustainable energy devices, such as solar cells. An array of silicon nanowires SiNWs, beside having excellent light antireflection properties, provide opportunities to design light trapping and carrier collection processes independently. *Also semiconductor ZnO has been the focus of research for many applications for the last several years because the material is nontoxic, chemically stable, and biocompatible with a direct wide bandgap, strong ionic bonding, and exciton binding energy 60 meV. *Despite the significant promises offered by these nanostructures, there are still several challenging issues related to physical properties of these elements; for example, in the case of SiNW solar cells, surface and interface recombination, surface roughness, mechanical and chemical stability, surface morphology, doping control, integration with other modules, and device packaging are some of these issues. In the case of ZnO, in many applications well-distributed and highly oriented NWs are of crucial importance. Furthermore, controllable fabrications of p-type or n-type ZnO NWs are the key for applications in nano optoelectronic devices since, p-type ZnO NWs exhibit a band gap reduction and strong acceptor-related photoluminescence and the n-type NWs have band gap broadening with a strong donor-bound exciton. *Therefore, preparing cost-effective and high quality of these nanowires, for any specific application on a large scale and with high throughput, is considered to be very challenging task.*The general scope of this proposal is the design, fabrication, and characterization of arrays of silicon and ZnO semiconductor nanowires/nanostructures for various applications. Works will be focused on research and investigations on the fundamental issues related to structures, physical properties, and fabrication of nanostructures with applications in photonics, energy, and sensing devices. The low cost of the developed technique is considered as an important factor. Finally, we design and fabricate devices based on the most promising elements produced in this work; our focus will be on developing a gas ionization sensor (GIS) and photovoltaic devices based on the nanowires/structures grown in this proposal. Therefore, in this proposal the following two main objectives will be studied:*1) Investigating methods to grow low cost but high quality with large throughput of zinc oxide and silicon nanowires. The techniques should enable us to control the morphology, size, aspect ratio, and conductivity of these nanostructures during the growth. Issues like doping, orientation, distribution, and uniformity of the array of nanowires will be addressed. *2) Developing devices based on the generated nano structures described in the first objective. A gas ionization sensor as well as PV devices will be designed and fabricated using the ZnO and silicon nanowires. The possibility of applying these structures for the purpose of hydrogen storage will be investigated.*This proposal will have significant impact on reducing our environmental pollutions in two ways: first by developing PV devices to generate clean and renewable energy, and secondly, by developing a miniaturized GIS to detect pollutant gases.