FORMATION AND PHOTOLUMINESCENCE CHARACTERIZATION OF QUANTUM-WELL WIRES USING MULTIATOMIC STEPS GROWN BY METALORGANIC VAPOR-PHASE EPITAXY

GaAs/AlGaAs quantum well wires (QWWs) were successfully fabricated using multiatomic steps on GaAs vicinal substrates by metalorganic vapor phase epitaxy (MWE). Coherent multiatomic steps with extremely straight step edges were observed on GaAs and AlGaAs epitadally grown layers on vicinal substrates over a wide observation area by atomic force microscopy (AFM). Formation of QWW structures is due to the fact that the GaAs growth rate on AlGaAs with multiatomic steps is much larger at the corners of steps than on the terraces. GaAs QWWs at the corners of steps accompanied by quantum wells (QWs) on the terraces were observed in cross-sectional transmission electron microscope (TEM) images. Photoluminescence (PL) of QWWs was measured at 20 K. The PL peak energy of the QWW structures grown on 5.0 degrees-misoriented substrates was 23 meV smaller than that of a reference QW structure on an exactly oriented substrate. Since the total amount of the grown material is basically the same for both structures, this peak energy shift indicates the formation of quantum-wire-like structures at the corners of multiatomic steps. Furthermore, this observed red shift is in good agreement with a simple theoretical estimate of the QWW structures observed by TEM. These results suggest that the present novel fabrication method of QWWs is very promising for the formation of uniform nano-meter size quantum wires without any processing damage.