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在超高真空化学汽相淀积设备(UHV/CVD)上生长了小尺寸、大密度、垂直自对准的Ge量子点。采用原子力显微镜分析量子点的尺寸,可优化其生长温度和时间,在550℃,15s的条件下生长出尺寸最小的量子点,直径30nm,高约2nm。最上层多层结构Ge量子点中岛状量子点的比例为75%,其直径66nm,高11nm,密度4.5×109cm-2。利用透射电子显微镜分析了垂直自对准的Ge量子点的截面形貌,结果表明多层结构Ge量子点是垂直自对准的。Ge量子点及其浸润层的喇曼谱峰位分别为299cm-1和417cm-1,说明Ge量子点是应变的并且界面存在互混现象。采用光荧光谱分析了Ge量子点的光学特性。
Small, large-density, and vertical self-aligned Ge quantum dots were grown on ultra-high vacuum chemical vapor deposition equipment (UHV / CVD). Atomic force microscopy was used to analyze the size of the quantum dots to optimize the growth temperature and time. The smallest quantum dots were grown at 550 ℃ for 15s with a diameter of 30nm and a height of about 2nm. The ratio of island-shaped quantum dots in the uppermost multi-layer structure of Ge quantum dots is 75%, which is 66 nm in diameter, 11 nm in height and 4.5 × 109 cm -2 in density. The cross-sectional morphology of the vertically self-aligned Ge quantum dots was analyzed by transmission electron microscopy. The results show that the Ge quantum dots of the multilayer structure are vertically self-aligned. The Raman peak positions of Ge quantum dots and its wetting layer are 299cm-1 and 417cm-1, respectively, indicating that the Ge quantum dots are strained and the interface is intermixed. The optical properties of Ge quantum dots were analyzed by fluorescence spectroscopy.