FORMATION AND CHARACTERIZATION OF INGAAS STRAINED QUANTUM WIRES ON GAAS MULTIATOMIC STEPS GROWN BY METALORGANIC VAPOR-PHASE EPITAXY

We investigate the formation of self-organized InGaAs quantum wires (Q WRs) on coherent GaAs multiatomic steps grown on vicinal GaAs substrat es. In our previous study, GaAs QWRs were formed at the edge of AlAs m ultiatomic steps grown by metalorganic vapor phase epitaxy (MOVPE). We also found that coherent multiatomic steps formed on GaAs tend to be disturbed during AlAs growth. In the present investigation, we clarify that a thin InGaAs layer with less than 0.15 In content grows in step flow growth mode from the edge of GaAs multiatomic steps, while that with more than 0.2 In content grows in three-dimensional nucleation an d growth mode at the edge of multiatomic steps due to the strain effec t. Next, we fabricate InGaAs/GaAs strained QWRs at the edge of coheren t GaAs multiatomic steps. Locally thick InGaAs QWR structures are obse rved by a transmission electron microscope. Photoluminescence (PL) mea surements reveal that the PL spectra of InGaAs QWR samples show lower energy shift (red-shift) by about 30 meV compared to those of quantum well ones due to the formation of InGaAs QWRs at the edge of coherent GaAs multiatomic steps.