Transmission electron microscopy and photoluminescence characterization ofInGaAs strained quantum wires on GaAs vicinal (110) substrates

We have used transmission electron microscopy (TEM) and photoluminescence ( PL) to study InGaAs/AlGaAs strained quantum wires (QWRs) grown by molecular beam epitaxy (MBE) on GaAs vicinal (110) substrates. The cross-sectional T EM image reveals that InGaAs QWRs structures are naturally formed on AlGaAs giant steps. In the plan-view TEM images, the fringe pattern in the giant- step region is observed for InxGa1-xAs layers with x less than or equal to 0.4. We measured the separation of the fringe in the plan-view TEM images a nd compared the result with the calculated fringe separation. From this res ult, we conclude that the fringes observed in the plan-view TEM images are moire fringes. PL spectra of the InGaAs QWRs samples reveal 80-meV shifts t o lower energy with respect to the spectrum of a quantum well (QWL) grown o n a (001) substrate under the same conditions. We also measured the polariz ation anisotropy of the PL spectra from the QWRs. The PL peak shifts system atically toward higher energy with decreasing InGaAs thickness. The degree of polarization for the InGaAs QWRs was about 0.29. The PL observation evid ences the carrier confinement in the QWRs. These results indicate that loca lly thick InGaAs strained QWRs were successfully formed at the edge of AlGa As giant steps.