Analysis And Parameter Optimisation Of Self-Organized Quantum Dots Using Kinetic Monte Carlo Simulation

This work was supported by the National Basic Research Program of China "973" (No.2003CB314901) , and the National Natural Science Foundation of China (No.60644004) .Quantum dots have drawn great attentions due to their potential applications in fabrication of a wide variety of optoelectronic and microelectronic devices, such as light emission diodes, solar cells, single electron transistors and in particular semiconductor quantum dot lasers for optical communications. Having an array composed of many uniformly sized and regularly ordered islands is the key for applications in modern semiconductor devices with quantum dots. Using self-organization effects represented in the Stranski-Krastanov growth mode^[1-3] is a promising way to gain highly efficient quantum dot layers.Kinetic Monte Carlo (KMC) simulations are used to simulate the relaxation processes of a system away from equilibrium. By defining a binding energy to represent the strain effect, KMC can simulate nucleation and growth of sub-monolayer islands, and the simulation results for growth of InAs/ GaAs and Ge/ Si quantum dots agree well with experiments.The thesis is organized with an introduction for the basic theory, background, model and methods. The theory of KMC is introduced in detail.The key part of this thesis is the KMC simulation for the growth of self-assembled InAs quantum dots array on a GaAs substrate with periodic strain-relief patterns. The study is focused on the influence of important parameters, such as growth temperature, growth interruption and growth rate, on sub-monolayer forming on top of the wetting layer. It is demonstrated that uniformly sized and regularly ordered island arrays can be obtained by controlling these parameters, by means of analyzing surface morphology, average island size, island size distribution andstandard deviation of island size distribution in detail. The size and the order of island arrays will greatly affect location and size of quantum dots in sequent 3-D growth.Further more, a 3-D model for the simulation of film and quantum dot's growth is established, and some preliminary results are gained. This is a good starting point for the future research.