Photoluminescence characteristics of selectively grown GaAs and AlGaAs/GaAs quantum wells

GaAs and AlGaAs/GaAs multiple quantum wells (MQW) were selectively deposited on GaAs substrates patterned with native oxide, and photoluminescence (PL) characteristics of both the single crystal grown in open windows and the polycrystalline material deposited on the oxide masks were studied. Well-resolved distinct quantum-well (QW) transition peaks indicate no degradation of the epitaxial material quality in the small single-crystal areas. The PL of polycrystalline GaAs is very weak and the peak is centered around the near-band-edge transition energy of GaAs. Polycrystalline MQW structures exhibit much stronger PL signals, and the peak position shifts corresponding to the widths of the QWs grown. These results suggest that the quantum size effect is preserved in the polycrystalline material.