Photoinduced electron coupling in δ-doped GaAs/${\mathrm{In}}_{0.18}$${\mathrm{Ga}}_{0.82}$As quantum wells

We have measured the Shubnikov–de Haas (SdH) effect on δ-doped GaAs/${\mathrm{In}}_{0.18}$${\mathrm{Ga}}_{0.82}$As quantum wells for the magnetic field up to 12 T at the temperature of 1.2 K. We found two SdH oscillations due to the lowest two subbands in the ${\mathrm{In}}_{0.18}$${\mathrm{Ga}}_{0.82}$As well with the electron densities of 14.12 and 11.02×${10}^{11}$ ${\mathrm{cm}}^{\mathrm{-}2}$ and the parallel conduction due to the electrons of about 4.86×${10}^{11}$ ${\mathrm{cm}}^{\mathrm{-}2}$ 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 ${\mathit{E}}_0$ increases but that for ${\mathit{E}}_1$ decreases. We believe that the reduction of SdH oscillation for ${\mathit{E}}_1$ is due to the electron coupling with ${\mathit{E}}_{\mathrm{\delta }}$ when the V-shaped potential well is lowered by the illumination. In addition, the intersubband scattering between ${\mathit{E}}_0$ and ${\mathit{E}}_1$ becomes less important than screening effect for ${\mathit{E}}_0$ when ${\mathit{E}}_{\mathrm{\delta }}$ coupled with ${\mathit{E}}_1$. © 1996 The American Physical Society.