Electron tunneling via gamma- and chi-states in GaAs/Al0.35Ga0.65As double quantum well structures

Non-resonant electron tunneling through a 6nm thick Al sub 0.35 Ga sub 0.65 As barrier is investigated by time-resolved photoluminescence. Application of hydrostatic pressure at 5 K reveals that tunneling via virtual X-states is at least 800 times less efficient than via virtual Gamma-states. Above 24.5 kbar an extremely fast scattering of electrons out of the n=1 quantized level of the narrower quantum well into real X-states in the barriers is observed.