Single-particle and transport scattering times in narrow GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum wells

The in-plane motion of electrons in narrow GaAs/${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As multiple quantum wells is studied experimentally and theoretically as a function of the electron density ${\mathit{n}}_{\mathit{s}}$ and the well width ${\mathit{L}}_{\mathit{z}}$. Two characteristic lifetimes—the single-particle relaxation time ${\mathrm{\tau }}_{\mathit{s}}$ and the transport scattering time ${\mathrm{\tau }}_{\mathit{t}}$—are obtained from magnetotransport measurements. By comparing ${\mathrm{\tau }}_{\mathit{s}}$ and ${\mathrm{\tau }}_{\mathit{t}}$ with detailed calculations, the contributions of interface roughness, remote impurity, and alloy disorder scattering are investigated separately.