Extremely Flat Interfaces in In_xGa_1-xAs/Al_0.3Ga_0.7As Quantum Wells Grown on (411)A GaAs Substrates by Molecular Beam Epitaxy

Abstract

Effectively atomically flat interfaces over a macroscopic area (super-flat interfaces) have been achieved in pseudomorphic In x Ga 1- x As/Al 0.3 Ga 0.7 As ( 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.