Extremely Flat Interfaces in InxGa 1-xAs/Al 0.3Ga 0.7As Quantum Wells Grown on (411)A GaAs Substrates by Molecular Beam Epitaxy

Effectively atomically flat interfaces over a macroscopic area (super-flat interfaces) have been achieved in pseudomorphic In x Ga1-x As/Al0.3Ga0.7As (x = 0.0, 0.04, 0.07) quantum wells (QWs) with well widths (L w) of 1.2–11.8 nm grown on (411)A GaAs substrates at 520°C by molecular beam epitaxy (MBE). A single, sharp photoluminescence (PL) peak was observed for each QW over the large area of the wafer (8 mm ×5 mm). The linewidths for narrow QWs (L w = 2.4 nm) were 8.9 meV (x = 0.04) and 9.9 meV (x = 0.07) at 4.2 K, which were about 30% smaller than those of QWs simultaneously grown on conventional (100) GaAs substrates.