Suppression of magneto-intersubband resistance oscillations by large-scale fluctuations of the intersubband energy splitting

Low-temperature dependences of the amplitude of magneto-intersubband resistance oscillations ( $\Delta {{R}_{{{\text{MISO}}}}}$) on the magnetic field $B < 2$ T are studied in single GaAs quantum wells with the width ( ${{d}_{{{\text{SQW}}}}}$) from $22$ to $46$ nm and two occupied quantum confinement subbands ${{E}_{1}}$ and ${{E}_{2}}$. It is established that additional damping appears in dependences of $\Delta {{R}_{{{\text{MISO}}}}}$ on $1/B$ in the studied quantum wells, which is explained by the effect of large-scale fluctuations of the intersubband splitting ${{\Delta }_{{12}}} = {{E}_{2}} - {{E}_{1}}$ on the amplitude of oscillations $\Delta {{R}_{{{\text{MISO}}}}}$. It is found that the suppression of oscillations $\Delta {{R}_{{{\text{MISO}}}}}$ with the increase in $1/B$ is more efficient in “narrow” quantum wells. This experimental fact makes it possible to suppose that the main origin of fluctuations of ${{\Delta }_{{12}}}$ in the studied narrow quantum wells is large-scale fluctuations of the well width ${{d}_{{{\text{SQW}}}}}$. An expression taking into account the role of large-scale fluctuations of ${{\Delta }_{{12}}}$ in the damping of $\Delta {{R}_{{{\text{MISO}}}}}$ is obtained. The comparison of theory and experiment has made it possible to determine the average amplitude of fluctuations of the intersubband splitting in the studied GaAs quantum wells.