Tunneling process in AlAs/GaAs double quantum wells studied by photoluminescence

The tunneling process of photogenerated carriers in AlAs/GaAs double quantum well structures in which two wells have different widths (60 and 80 A) was studied by steady‐state and time‐resolved photoluminescence spectra. The tunneling process was found to play an important role for a barrier thickness narrower than about 40 A. The tunneling rate was determined as 2×1010 s−1 for a 30‐A barrier. The quantum‐mechanical penetration depth of the wave function into an AlAs barrier was estimated as 6 A from the barrier width dependence of luminescence intensity ratio between the two wells. The tunneling rate and penetration depth are consistent with a simple envelope function approximation with no Γ‐X mixing.