WELL-WIDTH DEPENDENCE OF PHOTOLUMINESCENCE EXCITATION-SPECTRA IN GAAS-ALXGA1-XAS QUANTUM-WELLS

Photoluminescence excitation spectra of high-quality GaAs-Al0.3Ga0.7As quantum wells with various widths have been measured at 77 K. It has been found that the luminescent intensity for excitation photon energies exceeding the barrier band-gap energy exhibits an oscillatory behavior against the well width. The results clearly show that the trapping efficiency of the excited electrons into a well strongly depends on the well width through the resonance and off resonance of the quantum-well levels with the conduction-band bottom of the barrier. © 1990 The American Physical Society.