Controllable growth of semiconductor nanometer structures
Introduction
Molecular beam epitaxy (MBE) self-assembled nanostructures in the mismatched system may be used in devices application as quantum dots (QD) and wires (QWR). The self-assembling of the dots and wires during MBE involves random atomic processes, and there are various structural nonuniformities in these structures which cover their intrinsic properties and hamper their applications. In this work, the efforts are made to control the growth of the self-assembled nanostructures in the In(Ga)As/GaAs and InAs/InAlAs/InP systems by adjusting and optimizing the growth parameters, and improvements in structural properties are achieved to some extent. In addition, some significant phenomenon is observed in the symmetry of spatial ordering of InAs wires on InP(001), which may result from some kinetic process during the self-assembling of the InAs wires.
Section snippets
InxGa1-xAs/GaAs
In the fabrication of InxGa1-xAs dots, GaAs substrate orientation, In composition x, and the annealing temperature are used as variable experimental parameters to improve the structural property in island size, shape and density. In addition, In0.5Al0.15Ga0.35As layer is introduced between GaAs substrate and the InGaAs dot layer. The effects of these factors on the structural properties of the InxGa1-xAs/GaAs QDs are investigated by atomic force microscope (AFM) and photoluminescence (PL).
Discussion on the symmetry of the alignment of InAs wires
The [001] direction is symmetrical in crystallography and it is easy to understand that the MBE InAs QWR array on the InP(001) is symmetrical about the growth direction and the symmetry is disrupted when the material is grown on the misoriented substrate. However, the asymmetry in the alignment of the MEE InAs QWR array on InP(001) requires some explanation.
The main difference between the MBE and MEE growth modes is that the surface atomic diffusion during growth is significantly enhanced in
Acknowledgements
This work is supported by the Special Funds for Major State Basic Research Project G20000683 and National Natural Science Foundation under the contract no 69976027.
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