Vertical stacking of strained InGaAs/GaAs quantum wires by chemical beam epitaxy

We have successfully fabricated Vertically stacked InGaAs/GaAs quantum wires (QWRs) on V-grooved substrate by chemical beam epitaxy (CBE). The low-temperature growth of GaAs layers effectively controlled Ga adspecies on the sidewalls resulting in the preservation of V-shape GaAs barriers for the multiple stacking of equal sized InGaAs QWRs. Consequently, we have achieved three crescent-shaped InGaAs QWRs with a size of 300 Angstrom x 500 Angstrom at the bottom of a single V-groove. Realization of these stacking structures enhances the quantum efficiency via the increment of the Vertical density of QWRs. From the photoluminescence measurement, we confirmed the existence of exciton ground states in InGaAs QWRs. Our results suggest a new possibility to achieve the vertical integration of strained InGaAs/GaAs QWRs, which would enhance the quantum efficiency. (C) 1998 Elsevier Science B.V. All rights reserved.