Laser based methods for enhancement of the photoluminescence of Si quantum dots by coupling to plasmonic particles

与体硅相比，硅纳米结构(量子点)，如硅纳米晶(Si-NC)或非晶态硅团簇，在可见光和红外光谱范围内是高效的光发射器和吸光器。这其中，归因于量子限制。因此，硅量子点(Si-QD)作为集成有源发射体在硅光子学中引起了极大的关注。在光伏和数据存储方面的应用方面，这样的硅量子点也有很大的潜力：在含有硅纳米管的太阳能电池中，以前效率低下的太阳光光谱部分可能会得到更好的利用。尽管已经取得了许多成果，但硅量子点的光吸收和发射效率仍然不足以满足许多应用的需要。因此，该项目的目的是证明，通过将硅量子点与等离子体(金属)纳米颗粒相耦合，可以提高这种效率。具体地说，金纳米粒子(Au-NP)将通过激光辐射的方式注入到含有氧化物基质的Si-QD中。这里，植入是指以纳米颗粒的形式将原本涂覆在表面上的金插入到表面下的区域。Si-QD是通过SiOx薄膜(x&lt；2)的热退火而产生的。此外，还将研究激光辐照产生的硅量子点。通过控制规则有序的Si-QD和Au-Np之间的距离，可以提高其吸收和发射效率，并调节其辐射特性。通常，金和硅的结构采用完全不同的工艺技术。因此，到目前为止，这种组合很少得到治疗。激光在金属和半导体元件中引起的各种材料改性(局部加热、相分离、去湿、颗粒形成、注入)使得在这方面仍然几乎没有被探索的过程成为可能。这里所追求的方法特别有希望，因为金属纳米颗粒的特性同时在两个方面被利用：一方面，它们作为产生硅量子点的局部加热器，从而克服了以前观察到的基于激光产生硅量子点的复杂情况。另一方面，这些Au-NP作为天线，增强了对Si-QD的定向吸收和发射。这些天线本身将通过形状形成(细长粒子或粒子行)和排列(二维阵列)进行优化。我们预计，结果将可转移到其他材料组合，因此将具有普遍重要性。

Silicon nanostructures (quantum dots) like Si nanocrystals (Si-NC) or amorphous Si clusters with particle diameters < 10 nm are – in contrast to bulk silicon – efficient light emitters and absorbers in the visible and infrared spectral range. This is, amongst others, attributed to quantum confinement. Therefore, Si quantum dots (Si-QD) are of great interest as integrated active emitters in Si photonics. Regarding applications in photovoltaics and data storage, such Si quantum dots have also great potential: previously inefficiently used spectral portions of the sunlight may be better utilized in Si-NC containing solar cells. In spite of numerous achievements, the efficiency of light absorption and emission of Si-QD is still not sufficient for many applications. The aim of this project is therefore to show that this efficiency can be enhanced by coupling the Si-QD to plasmonic (metallic) nanoparticles. Specifically, gold nanoparticles (Au-NP) will be implanted by means of laser radiation into a Si-QD containing oxide matrix. Here, implantation refers to the insertion of gold originally coated on the surface into a region beneath the surface in form of nanoparticles. The Si-QD are generated by thermal annealing of a SiOx-film (x < 2). The generation of Si-QD by laser irradiation will also be examined. By controlling the distance between regularly ordered Si-QD and Au-NP, the efficiency of absorption and emission will be enhanced and their radiation characteristics will be adjusted. Generally, completely different process technologies are used for structuring gold and silicon. Therefore, such combinations have rarely been treated so far. The various material modifications (local heating, phase separation, dewetting, particle formation, implantation) which can be caused by laser radiation in both the metal and the semiconductor components enable processes which are still almost unexplored in this context. The approach pursued here is especially promising, because the characteristics of metallic nanoparticles are simultaneously exploited in two ways: on the one hand, they serve as local heaters for the generation of Si-QD, so that the otherwise observed complications of the laser based generation of Si-QD are overcome. On the other hand, these Au-NP act as antennas for the enhanced and directional absorption and emission of the Si-QD. These antennas themselves will be optimized by shape forming (elongate particles or rows of particles) and arrangement (two dimensional arrays). We expect that the results will be transferable to other material combinations and therefore will be of general importance.