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利用应力释放模型计算了 Zn Cd Se/Ga As间的临界厚度 ,并以该临界厚度为基础 ,用 MOVCD设备在Stranski-Krastanow (S-K)生长模式下 ,外延生长了 Zn Cd Se量子点。用原子力显微镜和光谱测量的方法研究了量子点的演化过程。随着时间的推移 ,量子点发生了两种变化 ,即 Ostwald熟化过程和量子点的生成过程。另外 ,量子点由尖塔状逐渐演化为圆顶状。这种形状的变化可以用晶体生长模型进行解释。通过分析量子点样品的发光光谱 ,发现了两种发光机制 ,一种是零维量子点激子的发光 ,另一种是二维激子的发光。随着量子点生长完毕与加盖层之间间隔时间的增加 ,零维激子对二维激子发光的比值增加 ,且发光峰位明显红移。这从另一方面验证了由原子力显微镜直接观测到的量子点的演化过程
The critical thickness of Zn Cd Se / Ga As was calculated by stress relaxation model. Based on this critical thickness, Zn Cd Se QDs were epitaxially grown by MOVCD in Stranski-Krastanow (S-K) growth mode. The evolution of quantum dots was studied by atomic force microscopy and spectrometry. Over time, two changes have taken place in quantum dots, the Ostwald maturation process and the generation of quantum dots. In addition, the quantum dots gradually evolve from minaret to dome shape. This shape change can be explained by the crystal growth model. By analyzing the luminescence spectra of quantum dot samples, we found two luminescence mechanisms, one is the emission of zero-dimensional quantum dot excitons and the other is the emission of two-dimensional excitons. With the increase of the interval between the growth of quantum dots and the capping layer, the ratio of zero-dimensional excitons to two-dimensional excitons increases and the luminescence peak shifts red markedly. This, on the other hand, validates the evolution of quantum dots observed directly by atomic force microscopy