Rearch On Physical Properties Of Semeiconductor Nano-Materials Based On The Effective Mass Theory

In modern times, because if the nano functional units being integrated is the measurement of Semiconductor nano technology development, the preparation technology of Quantum dots growth and the application of photoelectric devices become the frontier in condensed matter physics and semiconductor nanotechnology.This thesis covers the following three contributions:1. The strain, electron energy levels of InAs/GaAs(001) quantum dot with GaNAs strain compensation layer (SCL) are investigated. The results show that both the hydrostatic and biaxial strain inside the QDs with GaNAs SCL are reduced compared with those with GaAs capping layers. Moreover, most of the compressive strain in the growth surface is compensated by the tensile strain of GaNAs SCL, which implies that the influence of the strain environment the next layer QD’-s growth surface is weak and suggest that the homogeneity and density of QDs can be improved. Our results are consistent with the published experiment literature. GaNAs SCL influences the strain and band edge in the study, as is known, the strain and the band offset affect electronic structure, which shows that SCL is proved to be used to tailor emission wavelength of QDs. Our research helps to better understand how the strain compensation technology is applied to the growth of multiple stacks QD which are useful in solar cells and laser devices.2. We show Nano mechanics is useful to dynamically control the optical response of self-assembled quantum dots, giving a method to shift electron and heavy hole levels, interval of electron and heavy hole energy levels, and the emission wavelength of QDs. The strain, the electron energy levels and heavy hole energy levels of InAs/GaAs(001) quantum dots with vertical Nano mechanics are investigated. Both of the lattice mismatch and Nano mechanics are considered at the same time. The results show that the hydrostatic and the biaxial strains inside the QDs with Nano mechanics vary with different Nano mechanics. That gives control for tailoring band gaps and optical response. Moreover, due to strain-modified energy, the band edge is also influenced by Nano mechanics. Nano mechanics is shown to influence the band edge. As is known, the band offset affects the electronic structure, which shows that the Nano mechanics is proved to be useful to tailor the emission wavelength of QDs. Our research helps to better understand how Nano mechanics can be applied to dynamically control the optics of quantum dots.3. By three-dimensional kinetic Monte Carlo simulations the effect of the temperature (T), the flux rate (F), the total coverage (C) and the interruption time (t) on the distribution and the number of self-assembled InAs/GaAs (001) Quantum Dot (QD) islands, which shows that a higher temperature, a lower flux rate and a longer growth time correspond to a better island distribution. The relations between the number of islands and the temperature and the flux rate are also successfully simulated. It is observed that for the total coverage lower than0.5ML, the number of islands decreases with the temperature increasing for other growth parameters is fixed and the number of islands increases with the flux rate increasing when the deposition is lower than0.6ML and other parameters are fixed.