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The injection of photoexcited carriers into higher subbands by resonant tunneling in GaAs- AlAs superlattices is directly observed by photoluminescence spectroscopy. For a conduction subband spacing larger than the longitudinal optical phonon energy, the relative occupation of the second subband is much smaller than one. However, if the conduction subband spacing is below the longitudinal optical phonon energy, the relative occupation increases, but so far no intersubband inversion has been detected.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. |
