State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China. Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China.
Nanotechnology. 2017 Mar 17;28(11):115701. doi: 10.1088/1361-6528/aa5b3d. Epub 2017 Jan 31.
High-quality Ge nanostructures are obtained by molecular beam epitaxy of Ge on Si(001) substrates at 200 °C and ex situ annealing at 400 °C. Their structural properties are comprehensively characterized by atomic force microscopy, transmission electron microscopy and Raman spectroscopy. It is disclosed that they are almost defect free except for some defects at the Ge/Si interface and in the subsequent Si capping layer. The misfit strain in the nanostructure is substantially relaxed. Dramatically strong photoluminescence (PL) from the Ge nanostructures is observed. Detailed analyses on the power- and temperature-dependent PL spectra, together with a self-consistent calculation, indicate the confinement and the high quantum efficiency of excitons within the Ge nanostructures. Our results demonstrate that the Ge nanostructures obtained via the present feasible route may have great potential in optoelectronic devices for monolithic optical-electronic integration circuits.
通过在 200°C 的 Si(001) 衬底上对 Ge 进行分子束外延，并在 400°C 的温度下进行原位退火，得到了高质量的 Ge 纳米结构。通过原子力显微镜、透射电子显微镜和拉曼光谱对其结构特性进行了全面的表征。结果表明，除了在 Ge/Si 界面和随后的 Si 覆盖层中存在一些缺陷外，它们几乎没有缺陷。纳米结构中的失配应变得到了很大程度的松弛。从 Ge 纳米结构中观察到了显著的强光致发光（PL）。对功率和温度相关的 PL 光谱的详细分析，以及自洽计算，表明了激子在 Ge 纳米结构中的限制和高光子效率。我们的结果表明，通过目前可行的途径获得的 Ge 纳米结构在用于单片光电子集成电路的光电设备中可能具有巨大的潜力。
