Fabrication of semiconductor nanoparticles doped with active impurities and optical properties of single impurity-doped semiconductor nanoparticles

在本项目中，我们制备了具有活性杂质和发光中心的半导体纳米颗粒，并研究了单一杂质掺杂的半导体纳米颗粒的光学性质。杂质掺杂纳米颗粒的制备方法很多，包括胶体化学、溶胶-凝胶化学和离子注入合成。我们研制了扫描近场光学显微镜，用于单个纳米颗粒的光学研究。用选择激发光谱和低温扫描近场光学显微镜研究了透明膜中单个半导体纳米颗粒的光学性质。自由激子和浅杂质发光呈现窄线宽，其峰值能量依赖于纳米粒子的尺寸。在低温下，即使在单一的纳米粒子中，如施主-受主对和锰离子等深杂质发光也很广泛。强的电子-声子相互作用决定了深杂质发光的线宽。从时间分辨发光光谱和空间分辨发光光谱出发，阐明了掺杂光学活性杂质的半导体纳米颗粒的自由激子发光和杂质发光性质。

In this project, we have prepared semiconductor nanoparticles doped with active impurities and luminescence centers and studied optical properties of single impurity-doped semiconductor nanoparticles. Impurity-doped nanoparticles have been fabricated by many different methods including colloidal chemistry, sol-gel chemistry, and ion implantation synthesis. We have developed scanning near-filed optical microscope for the optical study of single nanoparticles. Optical properties of single semiconductor nanoparticles in transparent films have been studied by selective excitation spectroscopy and scanning near-field optical microscopy at low temperatures. The free-exciton and shallow-impurity luminescence show narrow linewidths and their peak energies depend on the nanoparticle size. The deep-impurity luminescence such as donor-acceptor pairs and Mn ions is broad even in single nanoparticles at low temperatures. The strong electron-phonon interaction determines the linewidth of the deep-impurity luminescence. From time- and space-resolved luminescence spectroscopy, we clarify the free-exciton and impurity luminescence properties of single semiconductor nanoparticles doped with optically active impurities.