Simulation model for self-ordering of strained islands in molecular-beam epitaxy

Precise Arrays of Epitaxial Quantum Dots Nucleated by In Situ Laser Interference for Quantum Information Technology Applications

Precisely ordered arrays of InAs quantum dots are formed on a nanoisland-structured GaAs (100) surface using in situ laser interference during self-assembled molecular beam epitaxial growth. Nanoislands induced by single-pulse four-beam laser interference act as preferential nucleation sites for InAs quantum dots and result in site occupation dependent on the size of nanoislands, the InAs coverage, and the laser parameters. By optimizing the growth and interference conditions, regular dense ordering of single dots was obtained for the first time using this in situ noninvasive approach. The photoluminescence spectra of the resulting quantum dot arrays with a period of 300 nm show good optical quality and uniformity. This technique paves the way for the rapid large-scale fabrication of arrays of single dots to enable quantum information technology device platforms.

Engineering of 3D self-directed quantum dot ordering in multilayer InGaAs/GaAs nanostructures by means of flux gas composition

Lateral ordering of InGaAs quantum dots on the GaAs (001) surface has been achieved in earlier reports, resembling an anisotropic pattern. In this work, we present a method of breaking the anisotropy of ordered quantum dots (QDs) by changing the growth environment. We show experimentally that using As(2) molecules instead of As(4) as a background flux is efficient in controlling the diffusion of distant Ga adatoms to make it possible to produce isotropic ordering of InGaAs QDs over GaAs (001). The control of the lateral ordering of QDs under As(2) flux has enabled us to improve their optical properties. Our results are consistent with reported experimental and theoretical data for structure and diffusion on the GaAs surface.

Quantum-dot growth simulation on periodic stress of substrate

InAs quantum dots (QDs) are grown on the cleaved edge of an In(x)Ga(1-x)AsGaAs supperlattice experimentally and a good linear alignment of these QDs on the surface of an In(x)Ga(1-x)As layer has been realized. The modulation effects of periodic strain on the substrate are investigated theoretically using a kinetic Monte Carlo method. Our results show that a good alignment of QDs can be achieved when the strain energy reaches 2% of the atomic binding energy. The simulation results are in excellent qualitative agreement with our experiments.