快速率生长MBE InAs/GaAs(001)量子点

用快速率(1.0ML/s)生长MBE InAs/GaAs(001)量子点。原子力显微镜观察结果表明,在量子点体系形成的较早阶段,量子点密度N(θ)随InAs沉积量θ的变化符合自然指数形式N(θ)∝ek(θ-θc),这与以前在慢速生长(≤0.1ML/s)条件下出现的标度规律N(θ)∝(θ-θc)α明显不同。另外,在N(θ)随θ增加的过程中,快速率生长量子点的高度分布没有经历量子点平均高度随沉积量θ逐渐增加的过程。这些实验观察说明,以原子在生长表面作扩散运动为基础的生长动力学理论至少是不全面的,不适用于解释InAs量子点的形成。这些观察和讨论说明,即使在1.0ML/s的快速率生长条件下,量子点密度也可以通过InAs沉积量有效地控制在1.0×108cm-2以下,实现低密度InAs量子点体系的制备。

Growth of MBE InAs/GaAs(001) QuantumDots by the Rapid Rate

The quantum dots in MBE InAs/GaAs(001) were fabricated by the rapid rate of 1.0 ML/sThe evolution of these quantum dots with InAs deposition θ was investigated by atomic force microscope.The result shows that the number density N(θ) of the quantum dots varies with the InAs deposition θ in accordance with the natural exponential form N(θ)∝ek(θ-θc) at the early stage,which is significantly in contrast with the scaling law N(θ)∝(θ-θc)α as observed in the conventional low-rate growth(≤0.1 ML/s).In addition,as N(θ) increases with θ,the height histograms of the quantum dots grown at the rapid rate are remarkably different from that of the latter.These experimental observations indicate that the conventional standard nucleation theory in terms of atomistic diffusion cannot be applied to the growth of InAs quantum dots.Furthermore,a simple way was suggested to fabricate the InAs quantum dots with the density below 1.0×108 cm-2 at the rapid growth rate of 1.0 ML/s