Role of In_xGa_<1-x>As Layer Composition in Modifying Strain Fields and Carrier Confinement Potentials in a Close-stacked InAs/GaAs Quantum Dot System(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

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Role of the composition of In_xGa_<1-x>As strain-relief layer (SRL) in controlling the strain fields and consequent modification of band structures in a close-stacked multi-layer InAs/GaAs quantum dot (QD) system was investigated within the framework of continuum elasticity and model solid theory. It was predicted that strains in the QDs are significantly relieved in proportion to the In concentration in the In_xGa_<1-x>As SRLs between InAs QD and GaAs cap layer. The relaxation of strains caused substantial shift of the conduction band edge in the QDs mainly by the relief of hydrostatic strain component resulting in narrower bandgap within the QDs with increasing In concentration. It is interpreted that such strain relaxation and subsequent band structure modifications are responsible for the experimentally observed redshift of photo-luminescence (PL) spectra elsewhere. Therefore, together with existing experimental work, it is confirmed that conduction band edges of QD systems can be tailored by the control of the SRL composition allowing more flexibility in bandgap engineering.
社団法人日本物理学会の論文
2005-05-15