Photoinduced electron coupling in δ-doped GaAAs quantum wells

We have measured the Shubnikov-de Haas (SdH) effect on δ-doped GaAs/(Formula presented)(Formula presented)As quantum wells for the magnetic field up to 12 T at the temperature of 1.2 K. We found two SdH oscillations due to the lowest two subbands in the (Formula presented)(Formula presented)As well with the electron densities of 14.12 and 11.02×(Formula presented) and the parallel conduction due to the electrons of about 4.86×(Formula presented) in the V-shaped potential well. After the illumination of the sample for different time periods, the electron densities of the two subbands oscillate, and the amplitude of SdH oscillation for (Formula presented) increases but that for (Formula presented) decreases. We believe that the reduction of SdH oscillation for (Formula presented) is due to the electron coupling with (Formula presented) when the V-shaped potential well is lowered by the illumination. In addition, the intersubband scattering between (Formula presented) and (Formula presented) becomes less important than screening effect for (Formula presented) when (Formula presented) coupled with (Formula presented).