Correlations of Photoluminescence and Size Evolution of Si Quantum Dots in Amorphous Silicon Carbide

摘要:

通过磁控溅射技术和1100 ℃的高温后续退火处理，在富硅碳化硅中形成高密度、小尺寸的硅量子点。其微结构和光学特性由高分辨电镜和光致发光技术进行表征。结合斯托克斯偏移和高分辨电镜分析表明，由非晶碳化硅包覆的硅量子点存在α-Si、c-Si两种结构，并呈现多带隙特征，子带隙分布范围从2.3到3.5 eV，出现紫外光到绿光的光致发光特征峰；发现此特征的硅量子点尺寸分布在~1.0~4.0 nm；通过改变薄膜中的Si和C原子比例，以及改变退火参数可进一步优化和控制硅量子点的微结构

Abstract:

Silicon quantum dots (Si QDs) with dot density up to 9×1013 cm-2 in amorphous SixC (x>1) thin films were obtained by magnetron sputtering deposition and post-annealing process at 1100 oC. Photoluminescence measurement indicates a multi-band configuration in the range from ultraviolet to green (2.3~3.5 eV). The analysis of Stokes shift and HRTEM demonstrates that there exist two kinds of Si QDs embedded in silicon carbide dielectric matrix: α-Si QDs and c-Si QDs which show the multi-band characteristics. The photoluminescence is closely related with the microstructure size distribution of Si QDs from 1.0 to 4.0 nm. Moreover, the density and the size distribution of Si QDs can be improved further by optimizing the ratio of Si/C atoms as well as annealing parameters. This opens a route to fabricate all-Si tandem solar cell