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（ZnO）组成的纳米结构具有显著的物理性能，已成为各种应用的研究热点。硅纳米线除了在电子和光电子领域有许多应用外，还用于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抗反射特性外，还为独立设计光捕获和载流子收集工艺提供了机会。此外，半导体ZnO在过去几年中一直是许多应用的研究重点，因为该材料无毒，化学稳定，具有直接宽带隙，强离子键和激子结合能60 meV的生物相容性。*尽管这些纳米结构带来了巨大的希望，但这些元素的物理性质仍然存在一些具有挑战性的问题；例如，在SiNW太阳能电池的情况下，表面和界面重组、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都是其中的一些问题。在ZnO的情况下，在许多应用中，分布良好和高度定向的NWs是至关重要的。此外，p型或n型ZnO NWs的可控制造是纳米光电子器件应用的关键，因为p型ZnO NWs表现出带隙缩小和强受体相关的光致发光，而n型NWs具有强供体束缚激子的带隙展宽。*因此，制备具有成本效益和高质量的纳米线，用于任何大规模和高通量的特定应用，被认为是非常具有挑战性的任务。*本提案的总体范围是设计、制造和表征用于各种应用的硅和ZnO半导体纳米线/纳米结构阵列。工作将集中在与结构，物理性质和纳米结构制造相关的基本问题的研究和调查，并在光子学，能源和传感设备中应用。该技术的低成本被认为是一个重要因素。最后，我们根据本工作中产生的最有前途的元件设计和制造器件；我们的重点将是开发一个气体电离传感器（GIS）和光电器件基于纳米线/结构生长在这个提议。因此，本课题将研究以下两个主要目标：*1)探索低成本、高质量、大产量的氧化锌和硅纳米线的生长方法。这些技术将使我们能够在生长过程中控制这些纳米结构的形态、尺寸、纵横比和电导率。纳米线阵列的掺杂、取向、分布和均匀性等问题将得到解决。*2)基于第一个目标中描述的生成的纳米结构开发器件。使用氧化锌和硅纳米线设计和制造气体电离传感器以及PV器件。研究将这些结构应用于储氢目的的可能性。*这项建议将在两个方面对减少环境污染产生重大影响：一是发展光伏装置，以产生清洁和可再生能源；二是发展小型地理信息系统，以探测污染气体。

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.