Morphological information has been obtained using the strong near-infrared photoluminescence emitted by germanium (Ge) nanocrystals (NCs) coherently imbedded in SiGe alloy layers, grown by molecular beam epitaxy on Si substrates. The emission spectra are analyzed for the effects of strain, carrier confinement, and disorder over a wide range of Ge concentrations in the surrounding SiGe medium. This analysis provided significant insight into the properties of the Ge nanocrystals, including their size and shape. We also discuss the mechanisms leading to the high quantum efficiency observed for emission from the Ge nanocrystals at low temperatures. We indicate how direct gap behavior might be achieved for Ge NCs lattice matched within dilute Ge_1-ySn_y alloys, where tensile strain would be present in the NCs in all three directions.

使用由锗 (Ge) 纳米晶体 (NC) 发出的强近红外光致发光获得形态信息，该纳米晶体相干嵌入 SiGe 合金层中，通过分子束外延在 Si 衬底上生长。发射光谱分析了应变、载流子限制和无序对周围 SiGe 介质中各种 Ge 浓度的影响。该分析提供了对 Ge 纳米晶体特性的重要洞察，包括它们的大小和形状。我们还讨论了导致在低温下从 Ge 纳米晶体发射观察到的高量子效率的机制。我们指出了在稀 Ge _1-y Sn _y内匹配的 Ge NCs 晶格如何实现直接间隙行为 合金，其中在所有三个方向上的 NC 中都存在拉伸应变。