OPTICAL SPECTROSCOPY OF SELF-ORGANIZED NANOSCALE HETEROSTRUCTURES INVOLVING HIGH-INDEX SURFACES

Similar effects are responsible for self-organization of periodically corrugated surface structures and ordered dot arrays on crystal surfac es. Strain relaxation on facet edges may result in the appearance of p eriodically corrugated surfaces for lattice-matched growth. Strain rel axation on facet edges and island interaction via the strained substra te act as driving forces for the formation of ordered arrays of unifor m, strained lattice-mismatched islands on a crystal surface. A pseudop eriodic square lattice is manifested for the InAs-GaAs(100) system. Le ss ordered dots are formed on the GaAs(100) surface with a 4 monolayer GaSb deposition. New experimental methods are applied for the charact erization of faceted nanoscale structures. For GaAs-AlAs multilayer st ructures grown on (311)A substrates, interface corrugation results in optical anisotropy of the same sign as expected from the low symmetry growth direction, making the main origin of the anisotropy unclear. Ou r quantitative optical reflectance and reflectance anisotropy studies show that the interface corrugation plays an important role for thin ( less than 4 nm) GaAs layers. Mesa arrays from samples with InAs quantu m dots grown on (100) surface are fabricated. The photoluminescence in tensity is found to depend only weakly on the mesa size (1000 nm to 25 0 nm). The estimated electron-hole pair capture time into the InAs dot at room temperature is less than 1 ps. We also found a weak dependenc e of the threshold current density on the deep mesa stripe width (down to 3 mu m) in the case of room temperature operated quantum dot injec tion lasers.