Oscillator-strength modification of Stark ladder transitions due to resonance-induced wavefunction delocalization in a GaAs/AlAs superlattice under the electric field
نویسندگان
چکیده
Spatially direct and indirect Stark ladder optical transitions and their electric field induced evolution have been investigated in a GaAs/AlAs (LZ = 6.4 nm/LB = 0.9 nm) superlattice by low temperature photocurrent spectroscopy. When the ground and first excited electron Stark ladder states resonate between the nearest neighbor wells, it is found that oscillator strengths of the direct (n = 0) and indirect (n = +1) Stark ladder transitions are strongly modified, accompanying enhanced anticrossings. The observed modification effects on the oscillator strength of the transitions are rigorously explained in terms of the wavefunction delocalization after the complete Wannier-Stark localization due to the resonant couplings between a) corresponding author. Tel. +81-93-884-3221; fax: +81-93-884-0879. electronic mail : [email protected]
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