E ectively atomically at GaAs=AlAs interfaces over a macroscopic area ("super-at interfaces") have been realized in GaAs=AlAs and GaAs=(GaAs)2 (AlAs)2 quantum wells (QWs) grown on (4 1 1)A GaAs substrates by molecular beam epitaxy (MBE). A single and very sharp photoluminescence (PL) peak was observed at 4.2 K from each GaAs=AlAs or GaAs=(GaAs) 2 (AlAs)2 QW grown on (4 1 1)A GaAs substrate. The full-width at half-maximum (FWHM) of a PL peak for GaAs=AlAs QW with a well width (Lw) of 4.2 nm was 4.7 meV and that for GaAs=(GaAs)2 (AlAs)2 QW with a smaller well width of 2.8 nm (3.9 nm) was 7.6 meV (4.6 meV), which are as narrow as that for an individual splitted peak for conventional GaAs=AlAs QWs grown on (1 0 0) GaAs substrates with growth interruption. Furthermore, only one sharp peak was observed for each GaAs=(GaAs) 2 (AlAs)2 QW on the (4 1 1)A GaAs substrate over the whole area of the wafer (7ร7 mm 2 ), in contrast with two-or three-splitted peaks reported for each GaAs=AlAs QW grown on the (1 0 0) GaAs substrate with growth interruption. These results indicate that GaAs=AlAs super-at interfaces have been realized in GaAs=AlAs and GaAs=(GaAs) 2 (AlAs)2 QWs grown on the (4 1 1)A GaAs substrates.