Li Yuanyuan, Liu Xiaoyu, Liang Tianyuan, Liu Wenjie, Fan Jiyang
School of Physics, Southeast University, Nanjing 211189, People's Republic of China.
J Chem Phys. 2022 Mar 7;156(9):094705. doi: 10.1063/5.0085019.
Silicon carbide is an important wide-bandgap semiconductor with wide applications in harsh environments and its applications rely on a reliable surface, with dry or wet oxidation to form an insulating layer at temperatures ranging from 850 to 1250 °C. Here, we report that the SiC quantum dots (QDs) with dimensions lying in the strong quantum confinement regime can be naturally oxidized at a much lower temperature of 220 °C to form core/shell and heteroepitaxial SiC/SiO QDs with well crystallized silica nanoshells. The surface silica layer enhances the radiative transition rate of the core SiC QD by offering an ideal carrier potential barrier and diminishes the nonradiative transition rate by reducing the surface dangling bonds, and, as a result, the quantum yield is highly improved. The SiC/SiO QDs are very stable in air, and they have better biocompatibility for cell-labeling than the bare SiC QDs. These results pave the way for constructing SiC-based nanoscale electronic and photonic devices.
碳化硅是一种重要的宽带隙半导体，在恶劣环境中有广泛应用，其应用依赖于可靠的表面，通过干氧化或湿氧化在850至1250°C的温度范围内形成绝缘层。在此，我们报告尺寸处于强量子限制区域的碳化硅量子点（QDs）可以在低得多的220°C温度下自然氧化，形成具有结晶良好的二氧化硅纳米壳的核/壳和异质外延SiC/SiO量子点。表面二氧化硅层通过提供理想的载流子势垒提高了核心碳化硅量子点的辐射跃迁速率，并通过减少表面悬空键降低了非辐射跃迁速率，结果量子产率得到了显著提高。SiC/SiO量子点在空气中非常稳定，并且它们比裸露的SiC量子点对细胞标记具有更好的生物相容性。这些结果为构建基于碳化硅的纳米级电子和光子器件铺平了道路。
