Microphotoluminescence characterization of cleaved edge overgrowth T-shaped InxGa1−xAs quantum wires

Abstract

Microphotoluminescence (micro-PL) characterization was performed for T-shaped InxGa1−xAs quantum wires (T-QWRs) fabricated by the cleaved edge overgrowth method with molecular beam epitaxy. The spatial distribution of optical properties in InxGa1−xAs T-QWRs was examined by means of PL intensity imaging and scanning micro-PL spectroscopy with about 1 μm spatial resolution. In the successfully fabricated 3.5-nm-scale In0.17Ga0.83As T-QWRs with Al0.3Ga0.7As barriers, uniform PL image and PL spectra from QWRs along the wire direction were observed, which indicates spatially uniform and high quality QWRs were formed. The effective lateral confinement energy of one-dimensional excitons was found to be 34 meV, showing the usefulness of InxGa1−xAs as a well material in T-QWR structures. On the other hand, in the unsuccessfully fabricated 4-nm-scale In0.09Ga0.91As T-QWRs with Al0.3Ga0.7As barriers, PL image and spectra were inhomogeneous. These results demonstrate the importance of flat cleaved surface and optimized overgrowth condition to fabricate uniform T-QWRs.